BREEDING
MISCELLANEOUS GRASSES
1

H. N. VINALL,2 Senior Agronomist;
M. A. HEIN, Agronomist, Division of Forage Crops and Diseases, Bureau of Plant Industry

[ABSTRACT.]  COMPARED with the work in several-other countries, very little has been done in the United States in breeding any of the grasses except timothy. Orchard grass, bluegrass, redtop, bromegrass, bentgrass, Bermuda grass, carpet grass, and all other grasses ordinarily used in seeding pastures and lawns are mixed populations consisting of many strains that vary in such important characteristics as date of maturity, disease resistance, leafiness, number and vigor of stolons and rhizomes, and viability and abundance of seed.  Because of these wide variations, there is a great opportunity for improvement by simple selection processes, and probably still greater possibilities in hybridization. The widely differing uses of grass, however, necessitate a close scrutiny and thorough examination of the variants from the standpoint of each possible use. Moreover, improved strains developed by British or other foreign workers are not likely to represent the best for our own country, since maximum values in plant breeding are attained only by aiming for close adaptation to local conditions. In the development of improved grasses, we shall have to solve our own problems by a systematic attack based on regional differences.

The grass family, known by botanists as the Gramineae, is the most important and widely distributed of all plants. Grasses are found from the Tropics to the Arctic Zone, and in deserts and swamps. To this group belong some of the most important cultivated crops such as corn, wheat, oats, rye, barley, rice, sugarcane, and the sorghums and millets.

Grass breeding really began in a remote time with the development of these crops from various species of wild grasses. This breeding, however, had for its purpose an increased production of food grain rather than any improvement in forage value. Pastoral agriculture was founded on the utilization of grasslands for grazing domesticated animals; and primitive peoples still migrate, with their flocks, in search of grass which provides the entire sustenance of these animals. It is only within the last 30 years that any serious effort has been made to increase the forage production of grasses.

In different parts of the world natural selection took place under the influence of climate, and thus we find the original grasslands of each country characterized by certain genera and species, which are native or indigenous there. As civilization developed and intercourse between nations became easy, the native grasses of each country were introduced and domesticated in countries having similar climates, so that grasslands are now less distinctive from a national viewpoint than formerly. However, there still remain more or less well-defined centers of development for each of the important grasses, and these centers are important as sources of breeding material.

GERM-PLASM SOURCES FOR VARIOUS GRASSES

Groups of related grasses have become concentrated in certain parts of the world as a result of their reactions to climatic conditions. It is in such regions that these genera are found in the greatest abundance, and here also the widest variation may be expected in habit of growth within the species. These development centers have been outlined broadly in figure 1, which may be considered as a graphic illustration of grass adaptations and the chief grass resources of the world, with the natural migration channels of these grasses indicated, of course, without any attempt to present details. The most important genera and species in each of the 16 regions are listed in table 1 (in the appendix). The boundaries or limits of these regions are obviously not exact, and wide variations occur within certain regions because of mountain ranges and other physiographic features that affect vegetation.


Region 1 includes most of western Europe where the annual precipitation is 20 inches or more and the temperatures are mild. Practically all of the so-called “tame” grasses now grown in southeastern Canada and the humid part of the United States north of the Cotton Belt are native in region 1 and were introduced from there by early settlers in North America. This region is rich in species and varieties of timothy, bluegrass, orchard grass, ryegrass, redtop, bentgrass, oatgrass, and fescue. Other grasses abundant in this region, but of little or no agricultural value, are velvet grass (Holcus lanatus),3 matgrass (Nardus stricta), and the other moorland grass (Molinia caerulea). These constitute the principal grass cover of wet heaths and moorlands throughout this region.

Region 2, the Mediterranean region of Europe and Africa, characterized by low rainfall and rather poor soils, is the native home of the annual species of Avena (wild oats), bromes, and fescues. Most of the winter annual grasses now growing in the foothills of southern California are of Mediterranean origin. In addition red fescue, canary and Harding grass originated in region 2. The esparto or alfa used in the manufacture of fine paper grows naturally in northern Africa. Grasses that are abundant in this region but of little value include many species of both Aristida and Stipa.

Region 3 includes the eastern or low-rainfall section of the Union of Soviet Socialist Republics and practically all of Siberia. Here, where the average rainfall is less than 20 inches and the winters are very severe, a group of extremely hardy and drought-resistant grasses has developed, including the crested wheatgrass which has proved so valuable on the northern Great Plains of the United States. On the dry, cold steppes are many species and varieties of wheatgrass (Agropyron), Wild-rye (Elymus), reedgrass (Calamagrostis), and “chee” or tshee” grass (Stipa). The small fescues such as the sheep fescue are present but not so characteristic of this region as the Agropyrons.

Region 4, including southeastern Union of Soviet Socialist Republics, western China, and that ancient cradle of the human race, Asia Minor, Persia, and Afghanistan, is peculiarly important as the native home of several cereal grasses. All of this region is very dry and a considerable part is actual desert. While not so important from a forage standpoint, the native grasses of this region include what are believed to be the progenitors of wheat, emmer, einkorn, and rye.  Numerous species of wheat (Triticum), rye (Secale), and their near relatives the goatgrasses (Aegilops and Haynaldia) are found here.  The wild barleys (Hordeum spp.) are common, and bulbous bluegrass (Poa bulbosa) is almost everywhere. Meadow foxtail, sweet vernalgrass, red fescue, and Johnson grass are other important grasses found in region 4.

Region 5 includes Tibet, the western provinces of China, and eastern Mongolia. This is a region of high mountain ranges, cold, dry plateaus, and deserts. On account of its inaccessibility less is known about the grasses of this region than of any other part of the world.  The grasses that have developed here would assuredly be drought-resistant and able to withstand other climatic extremes. At least four species of bluegrass and as many fescues have been reported from this region, along with several species of wheatgrass and wild-rye. Needlegrass (Stipa spp.) and sedges (Carex spp.) are widely distributed.

Region 6 includes eastern Siberia, Manchuria, northeastern China, Chosen, and Japan. Although attention has chiefly been given to the many soybean varieties in this region, it is also important as the home of most of our cultivated millets and that group of sorghums known as kaoliang. Foxtail millets, broomcorn millet (proso), and Japanese millet are all widely distributed and show a great variety of forms in this region. The Japanese lawngrass (Zoysia japonica) and Manila grass (Zoysia matrella), both of which appear valuable in the United States, are at home here. Among the less important grasses are many species of Arundinella, Calamagrostis, Ischaemum, and Panicum.

Region 7, including southeastern China, most of India, Burma, the Malay Peninsula, and adjacent islands, is largely tropical and has a heavy rainfall except in northern India. Such important cultivated crops originated in this region as sugarcane, rice, and bamboo; and also the forage grasses, Bermuda grass, Angleton grass, and centipede grass. There are many other species and varieties of Andropogon, Cynodon, Eleusine, Oryza, Panicum, Paspalum, Saccharum, and Sorghum that have not yet proved of value under cultivation but may be of some importance from a breeding standpoint. Cogon grass, said to be a useful pasture grass in China and the Philippine Islands, is of doubtful value in the United States on account of its aggressive rootstocks.

Region 8, including Australia, New Zealand, and Tasmania, has a very distinctive vegetation, and many of the native grasses of this region are found nowhere else in the world except in small experimental plantings. The interior of Australia is very dry, almost desertlike. Along the coast where rainfall conditions are favorable the pastures and meadows are composed almost entirely of grasses and legumes introduced from Europe. In the drier portions native grasses supply most of the forage, and the most important of these are perhaps Mitchell grass, Wallaby grass, kangaroo grass, red grass (Themeda sp.), Flinders grass, and tussock grass. On the sand ridges in the semidesert area spinifex (Triodia spp.) is very abundant. Common Mitchell grass, curly Mitchell grass, and Wallaby grass have all been introduced into the United States, but they seem to be of little value here. The tussock grass of New Zealand (Poa flabellata) appears to be a very desirable grass, but so far all attempts to introduce it have failed. So much of Australia is desertlike that many grasses such as the annual bromes, fescues, Avenas, and Hordeums, which are not considered desirable in the United States, are appreciated there.

Region 9 consists of the equatorial part of Africa, some of which is occupied by dense forest. In parts where the rainfall is not too heavy, grasses abound in the open places of the timbered areas and in exclusively grass-covered lands or savannas replete with wild game animals.  Here are found numerous species of Sorghum, Pennisetum, Panicum, Hyparrhenia, Andropogon, Ehrharta, and Themeda. Molasses grass and jaragua grass originated here, but are now more important in South America. In the highlands of Ethiopia are found many Hordeums (barley relatives). Sudan grass originated near Khartum, and other varieties of grass sorghum occur in profusion in this region.  Pearl millet is native here also and originally was an important food crop of the inhabitants.

Region 10 is composed of that part of Africa south of 10° S. latitude and the adjacent island of Madagascar. The annual rainfall varies from about 40 inches in the northern part to actual desert conditions in Bechuanaland and southwestern Africa. The rains come largely during the summer months (winter in the Northern Hemisphere), and in this period they are fairly adequate except in the desert regions of Bechuanaland and along the West Coast. Temperatures are rather high except in a very limited mountain section in eastern South Africa. Plants that have developed under these conditions in Africa are well adapted to the Cotton Belt of the United States. Practically all of our cultivated varieties of sorghum originated in this region, and from there came Rhodes grass, Natal grass, and woolly fingergrass. Many species of Chloris, Cynodon, Digitaria, Ehrharta, Hyparrhenia, and Themeda contribute forage for their domestic and wild animals. Grasses that are abundant but of little value include the Aristida and Trichopteryx species, especially the latter.

   Region 11 comprises most of Brazil, eastern Bolivia, Paraguay, Uruguay, and the northeastern part of Argentina. In this part of South America. the rainfall is heavy (30 to 70 inches) and the temperatures are subtropical to tropical. Here we find an immense area of open parklike grasslands, including the campos of Brazil and the pampas of Uruguay and Argentina. The basin of the Amazon, with a rainfall of over 80 inches annually, is a dense, junglelike forest of little importance from a grass standpoint. Notwithstanding the extent of the grasslands in South America, few if any of the native grasses have shown any forage value in the United States or in their homeland. The superior forage grasses of South America were almost without exception introduced from tropical Africa, the native pampas grass being used chiefly as an ornamental because it is unpalatable.  The molasses, jaragua, Guinea, and Para grasses all appear to have introduced many years ago and are now widely distributed in region 11. They provide a large proportion of the pasturage for livestock, which is one of the main sources of revenue in this region.

Region 12 comprises Chile and the western or Andean sections of Argentina, Bolivia, and Peru as far north as the Gulf of Guayaquil.  Except for southern Chile and Patagonia, this is a region of high altitudes and low rainfall. Although important as the native land of the potato and other Solanaceae, it does not appear promising as source of forage grasses.  Axonopus scoparius, a relative of carpet called “cachi” in Bolivia, is said to be a good pasture grass.  This is found on the moist meadows of the eastern slope of the Andes.  The forage in the high mountain valleys and plateaus is derived mostly from species of Festuca, Poa, Calamagrostis, and Muhlenbergia.  Grasses that are abundant but have little agricultural value comprise numerous species of Eragrostis, Stipa, Trisetum, and Piptochaetium.  The last-named genus is said to be encountered everywhere in this region, although it is uncommon in other parts of the world.

Region 13 includes southern Mexico, all of Central America and the West Indies, and Colombia, Venezuela, and Guiana in South America. This region, surrounding the Caribbean Sea and the Gulf of Mexico, is largely in the Tropics, but differences in altitude give it an extremely varied climate. It is also the home of the early Mayan civilization and the source of several of our most important food plants, including corn. In the Orinoco Basin of South America are the llanos, broad savannas or grasslands similar to the campos of Brazil. Several very useful forage grasses have been obtained from Region 13, where they appear to be indigenous. The best known of these are teosinte, gamagrass, Bahia grass, St. Augustine grass, Guatemala grass, carpet grass, and wildrice. This region also abounds in species of Trisetum, Setaria, and Andropogon, most of which are of little or no value agriculturally. Sourgrass (Trichachne insularis) is very common but worthless.

Region 14 in western North America comprises a broad expanse of rugged mountains, dry plains, and plateaus extending from the Peace River section of Canada to southern Mexico. In all this region the rainfall is very limited, varying from actual desert conditions to 20 inches annually, while the temperatures range from very hot in Mexico and Arizona to very cold in northern United States and Canada. The flora is rich in native grasses except for the desert areas, where the dominant vegetation consists of woody shrubs and cacti. Among the native grasses that contribute most to the sustenance of livestock are a great variety of wheatgrasses, bluestems or beardgrass, gramas, buffalo grass, sandgrass (Calamovilfa sp.), wild- ryes, fescues, bluegrasses, mesquite grasses (Hilaria sp.), and the Sacaton or dropseed grasses. Grasses that are common but of no particular value include the needlegrass (Aristida sp.), spear grass (Stipa sp.), and squirreltail grasses (Sitanion spp.). Foreign grasses that have proved adapted in this region include crested wheatgrass, awnless bromegrass, bulbous bluegrass, and Sudan grass.

Region 15, consisting of southeastern Canada and the northeastern United States, was originally occupied almost exclusively by hardwood and coniferous forests. Naturally, valuable native grasses are scarce except in the western part of the Corn Belt, which was from early days an open prairie carpeted with big bluestem and little bluestem. Both of these are excellent forage grasses. The rainfall in this region is usually adequate, and as the country was settled by people from Europe, the land when cleared of timber was seeded to introduced grasses from region 1. At the present time most of the pastures and meadows are occupied by these European grasses, which have proved admirably adapted to the climatic conditions here.  Foxtail millet and Japanese millet, introduced from Europe but natives of Asia, are also grown rather extensively. Reed canary grass, big bluestem and little bluestem are about the only native grasses that have proved important. Other native grasses of minor importance are noted in table 1, because they may be of some value from a breeding standpoint.

Region 16 is that part of the Eastern United States south of the 60° isotherm. This is the original Cotton Belt, and while limited in area, it has been set apart from region 15 because of its marked difference in grass flora. This region was also originally a forest, and when the timber was cleared off by settlers European grasses proved unadapted, but more tropical grasses from Asia, Africa, and Central America have occupied the cleared lands where the soil is sufficiently fertile for these introduced grasses to compete with the omnipresent native broomsedge and other Andropogons. The most important of the introduced grasses are Bermuda, carpet, Dallis, and Johnson grasses, and they provide the bulk of the pasturage and hay in the region. Napiergrass, Japanese cane, and pearl millet also thrive here, but will not be discussed further at this time, since the situation in regard. to grasses in the United States is presented in the appended detailed maps.  The native grasses, some of which may offer possibilities in breeding, are listed in table 1. Texas bluegrass is one of these already used in crosses with Kentucky bluegrass.

CLIMATIC ADAPTATION OF PRINCIPAL FORAGE GRASSES OF THE UNITED STATES

The effective improvement of grasses by breeding requires an understanding of their inherent climatic relationships. In the United States this relationship is best expressed by dividing the country into six regions as illustrated in figure 2. This generalized picture of a situation that has developed naturally under the influence of prevailing climatic factors provides a basis for the organization of grass breeding in this country. The introduction of other foreign grasses in the future may conceivably change the situation, especially in the Southwest.  At this time, however, the opportunities for success in breeding appear to lie in working with those grasses that have met the requirements of man and have been most productive during the past century. The most outstanding of these are discussed briefly.

In considering the distribution maps it must be understood that the limits indicated are not exact. Beyond the boundaries where a particular grass is really important it will be found less and less frequently struggling to survive under increasingly unfavorable conditions which results in an overlapping of adjacent distribution areas.


Figure 2.—Grasslands of the United States, showing the dominant type of grasses in each as determined by the climate.


KENTUCKY BLUEGRASS, CANADA BLUEGRASS, AND TIMOTHY

Kentucky bluegrass, Canada bluegrass, and timothy were introduced from Europe by the early settlers, and as the land was cleared of forest they spread over practically all of the humid part of the United States north of the 60° isotherm, as indicated in figure 3. In addition to the areas shown, these grasses are abundant in region 5 of figure 2, which is also humid. None of them is sufficiently drought-resistant to be grown successfully in arid or semiarid sections except under irrigation. These grasses have become the leading hay and pasture grasses of the United States and the adjacent sections of Canada. They proved so well adapted to climatic conditions here that they now occupy much more extensive areas in North America than they do in Europe.


Figure 3.—Sections of the United States where Kentucky bluegrass and Canada bluegrass are well adapted and of primary importance.

REDTOP AND THE BENTGRASSES

Although redtop and the bentgrasses (species of Agrostis) are not so important agriculturally as are Kentucky bluegrass and timothy, redtop is valuable for both hay and pasture on wet or acid soils, and the bentgrasses, because of their fine turf, are used extensively on lawns and golf courses. The sections where these grasses are of major importance are shown in figure 4, but they thrive equally as well in region 5 of figure 2, and the use of the bentgrasses for fine turf is common throughout the whole redtop region. Redtop is most highly regarded in Illinois, where most of the seed is produced. It seems better suited to the poorly drained, rather unproductive clay soils of that section than any other grass.


Figure 4.—Sections of the United States where redtop and the bentgrasses are well adapted and of primary importance.

ORCHARD GRASS AND TALL OATGRASS

The approximate range of distribution of orchard grass and tall oatgrass is shown in figure 5. Of these two introduced grasses, orchard grass is the more common and undoubtedly the more valuable because of its longevity and its value in pasture mixtures. It is more tolerant of shade than bluegrass and produces better on poor oils. The results obtained in the improvement of orchard grass in Europe and Australia lead to the belief that much may be accomplished with it here. One of the obvious points of weakness in tall oatgrass is seed shattering which has already been overcome by selecve breeding.


Figure 5.—Sections of the United States where orchard grass and tall oatgrass are well adapted and of primary importance.

BERMUDA, JOHNSON, AND DALLIS GRASSES

Bermuda, Johnson, and Dallis grasses together with carpet grass are the principal hay and pasture grasses of the Cotton Belt. All of them were introduced at a comparatively early date and have spread naturally over most of these States. Although Bermuda grass and Johnson grass are found more or less frequently north of the limits indicated in figure 6, they are sensitive to low temperatures and grow only during the frost-free period; hence they are unimportant outside of the section indicated in figure 6 except in the irrigated sections of southern California, Arizona, and New Mexico. In these States both are abundant, but Johnson grass especially is considered a weed and Bermuda grass is a doubtful asset. Both grasses invade irrigated cultivated lands and are difficult to control because of their aggressiveness. Dallis grass, however, is gradually coming to be recognized as a valuable constituent of pasture mixtures on irrigated lands in these States.


Figure 6.—Sections of the United States where Bermuda, Johnson, and Dallis grasses are well adapted and of primary importance.

CARPET, NAPIER, BAHIA, AND PARA GRASSES

Successively more tropical and less winter-hardy, carpet, Napier, Bahia, and Para grasses are confined almost entirely to sections of the United States indicated in figure 7 and to extreme southern parts of California and Arizona. Carpet grass is much more common than the other three and next to Bermuda grass is foremost in pasture improvement. Napier grass, because of its large, coarse growth, may be used effectively as a soiling or silage crop in addition to its value as a supplemental pasture.


Figure 7.—Sections of the United States where carpet, Napier, Bahia, and Para grasses are well adapted and of primary importance.

AWNLESS BROMEGRASS AND CRESTED WHEATGRASS

Awnless bromegrass and crested wheatgrass, unlike the grasses just discussed, are extremely winter-hardy, and both are very drought- resistant. Both were introduced from Europe and have been found most useful in the northern parts of the Great Plains and of the inter- mountain region (fig. 8). Bromegrass, however, is proving valuable in the North Central States in pastures and meadows, especially in mixtures with alfalfa.  The chief objection to it, the difficulty encountered in eradicating it, may be overcome by selective breeding. Grazing animals are very fond of both crested wheatgrass and bromegrass.


Figure 8.—Sections of the United States where awnless bromegrass and crested wheatgrass are well adapted and of primary importance.

NATIVE SHORT GRASSES AND PRAIRIE GRASSES
Buffalo grass, the gramas, mesquite grasses, bluestems, and wheatgrasses supply a very large part of the pasturage and wild hay produced in the Great Plains. The distribution areas of all of these except the wheatgrasses are indicated in figure 9. Much of this region is semiarid, and in order to grow successfully here grasses must be able to endure periods of severe drought. All of these with the exception of big bluestem are preeminently drought-resistant, and the chief object in breeding will be improvement in productiveness of forage and viable seed. The actual distribution of each grass is considerably wider than is indicated .on the map, which outlines the areas where each grass is of major importance and where their breeding is warranted. Big bluestem and little bluestem are adapted quite well to the outlying stippled area but are of minor importance there because most of the land is now under cultivation and introduced grasses are more productive. These two bluestems are found in small isolated colonies as far south as the Gulf coast. Indian grass is found growing in combination with the bluestems but rarely constitutes over 5 percent of the herbage.

Figure 9.—Sections of the United States where native short grasses and prairie grasses are well adapted and of primary importance.

SLENDER AND WESTERN WHEATGRASSES

Western wheatgrass is found growing naturally all over the Great Plains except the extreme southern part. In the depressions where the soil is heavier, western wheatgrass often occupies the land to the virtual exclusion of all other grasses. Its foliage is rather harsh but palatable and very nutritious especially when immature. Slender wheatgrass is more widely distributed than western wheatgrass, although it does not extend so far south in the Great Plains as the latter, and being a bunch grass it seldom occupies any large area to the exclusion of other grasses. The regions where these two native grasses are of importance are outlined in figure 10. Both are valuable for hay as well as pasturage, and less difficulty is found in obtaining viable seed of these wheatgrasses than of the other native grasses just discussed.


Figure 10.—Sections of the United States where slender wheatgrass and western wheatgrass are well adapted and of primary importance.

SUDAN, REED CANARY, AND OTHER GRASSES

The species that have been discussed include nearly all of the grasses of recognized importance in the United States except Sudan grass and reed canary grass. Sudan grass, an annual, has been found useful as an emergency hay crop and for summer pasture in all parts of the United States, although best suited to conditions in the middle and southern Great Plains. Reed canary grass is valuable on wetlands anywhere north of the 60° isotherm. Breeding activities will no doubt be most productive with these grasses, but there are many others that should not be ignored, since in them are found useful characters that may be transferred to the more important species by hybridization.

WHY THE BREEDING OF GRASS IS WORTH WHILE

APPROXIMATELY 60 percent (32)4, 5 of the total land area of the United States is grazed at least part of the year, and a major portion of the feed obtained by grazing animals is provided by grasses. It is estimated that in 1919 the grazing lands supplied about 49 percent (25) and in 1929 about 41 percent (33) of the total feed consumed by all classes of farm animals. If the 11,798,065 tons of hay from grasses other than timothy be included, approximately 43 percent of the sustenance of our farm livestock must be credited to miscellaneous grasses.

In addition to the farm animals there are in the United States over 1 million herbivorous game animals (31), including deer, elk, and antelope. Deer and elk are the most numerous, and they subsist largely by browsing on trees and woody shrubs, but 10 to 15 percent of the food of this group consists of grasses.6 The grasses are also important in providing food and cover for wild fowl.

Results obtained by soil erosion experiment stations7 indicate that on various soil types on slopes varying from 4 to 16 percent the losses of soil by erosion are from 650 to 4,600 times greater where the land is devoted to clean-cultivated crops as corn and cotton than on lands with a perennial-grass cover. Besides the reduction of direct losses through soil erosion and run-off, there is an additional benefit derived from a grass cover in the conservation of soil fertility, chiefly nitrogen and organic matter. It has been estimated that there is an average annual loss of 60 pounds of nitrogen per acre from cultivated soils.  Hopkins (8, p. 559), of Illinois, found 4,000 pounds of nitrogen per acre in the surface soil of land that had grown corn for 16 years, as compared with 4,914 pounds per acre in the soil of adjoining pasture land.  A determination of organic matter by the combustion method showed in the soil of old pastures 6.12 percent, new pastures 4.16 percent, and cultivated soil 2.44 percent (37).

Grass in lawns is the foundation of all landscape effects for private houses and public buildings. It has been estimated that over $100,000,000 is spent annually in the United States on private lawns and at least $10,000,000 for turf establishment and maintenance in cemeteries. To this must be added about $65,000,000 spent annually in providing the required turf on golf courses, athletic fields, and playgrounds, and $16,000,000 in providing a ground cover on airports, road shoulders, and railway embankments.

An increase in the acreage of grasses and legumes has been definitely adopted as a national policy because grasslands not only conserve the soil but also contribute to a better balanced agriculture. This places a larger emphasis on the work of the breeder.

POSSIBILITIES AND PROBLEMS IN BREEDING GRASSES

IN THE United States breeding of grasses has received little attention with the exception of timothy. Orchard grass, bluegrass, redtop, bromegrass, bentgrass, Bermuda grass, carpet grass, and all other grasses ordinarily used in seeding pastures and lawns are mixed populations consisting of many strains varying in such important characteristics as date of maturity, disease resistance, leafiness (fig. 11), number, and vigor of the stolons and rhizomes, and viability and abundance of the seed—to name only a few of the many variations. There is, therefore, a great opportunity for improvement by simple selection processes. The uses made of these grasses are varied as compared with those of cotton, tobacco, sugarcane, or even corn. This broad field of usefulness increases the opportunity, but it also implies a closer scrutiny and more thorough examination of the variants because a strain that may be of no value for hay purposes might be exactly the kind needed for pastures or lawns.


Figure 11.—Two selected strains of Kentucky bluegrass, showing the variations in leaf a width found in individual plants of commercial cultures.

It is now rather generally acknowledged that the maximum values in plant breeding are attained only by breeding plants adapted to local conditions. Improved strains are not ordinarily found superior under all conditions of soil and climate. There is therefore little reason to believe that the improved strains of grasses developed by British or other foreign workers will represent the best attainable here in the United States. Plant-breeding work with cereals has shown also that there are different strains of certain disease organisms, such as smut, and that a grain variety that is almost wholly immune to the ordinary smut may be susceptible to other strains of this disease. The same condition will probably prevail with reference to the diseases of forage grasses, which implies additional restrictions and necessitates better controlled tests in breeding.

   Opportunities for the accomplishment of practical results in the improvement of forage and fine turf grasses appear most promising in the following respects:
  1. Yield and viability of seed.
  2. Disease resistance.
  3. Ability to compete successfully with other plants.
  4. Increased vigor and ability to renew growth quickly after defoliation.
  5. Longevity, drought resistance, and winter hardiness.
  6. Tolerance to wet or saline soils.
  7. Palatability and nutritive value of herbage.
  8. Quality, durability, and uniformity of texture in turf.
INCREASING YIELD AND VIABILITY OF GRASS SEED

Many valuable grasses are notably shy seed producers. This is especially true of our native grasses, but it also applies to many of the introduced grasses. The failure to produce viable seed in sufficient quantity to supply the demand is a great handicap and often prevents an otherwise valuable grass from being grown on an extensive scale; it prohibits a wide use of native grasses in regrassing abandoned farm land in the Western States; for example, the gramas, buffalo grass, big bluestem and little bluestem, wheatgrass, and several other species would be seeded on millions of acres of these lands if good, germinable seed were available in commercial quantities. The same thing is true of many of the promising introduced grasses. Woolly fingergrass from South Africa gives indication of being an outstanding pasture grass for the poor upland soil of the Southeastern States, but it produces little or no seed. The Japanese lawngrass (Zoysia japonica) appears to be exactly the kind of grass needed for sodding airports and athletic fields.  It forms a tough, long-lived turf, which would endure rough usage and be more or less permanent. Here again seed production is negligible. Good seed of Dallis grass, Bahia grass, and centipede grass is scarce, and the use of these valuable pasture and lawngrasses is therefore limited.

PRODUCTION OF DISEASE-RESISTANT STRAINS

While diseases are not usually so destructive to the forage grasses as the rusts and smuts of cereal crops, there are several that present a definite handicap to the effective use of these grasses in certain localities. Sudan grass, immensely valuable in dry regions, is almost worthless in the humid portion of the United States from Washington, D. C., south to Florida, because of the ravages of foliage diseases.  Ergot is the chief factor limiting the production of Dallis grass seed.  A leaf-spot disease causes widespread damage to Kentucky bluegrass in pastures and lawns. Grass diseases are most feared, however, in the growing of fine turf on golf courses and lawns. Under certain conditions diseases like brown patch are the greatest menace to the fine turf grasses, especially bentgrass as it is grown and handled on the putting greens of golf courses and on lawns. Control of diseases of fine turf is possible through the application of fungicides, but the development of resistant strains or varieties is preferable. In the case of pasture and meadow grasses, the use of fungicides is not practical, and breeding for disease resistance is the only logical means of overcoming the difficulty.

REGULATING AGGRESSIVENESS BY BREEDING

Most of our cultivated cash crops are grown in pure stands and occupy the land for only 1 year. Aggressiveness or ability to compete with weeds and other plants is not, therefore, a factor of any importance in these crops. With perennial grasses, however, the ability to retain possession of the soil to the exclusion of weeds and less desirable grasses is a characteristic of major importance in permanent pastures.  In breeding grasses aggressiveness is a character that must be regulated. If itis too pronounced the grass becomes difficult to eradicate; is is true of quackgrass and Bermuda grass. Another disadvantage of pronounced aggressiveness is the difficulty of growing legumes in combination with such grasses. In pastures and hay meadows also, a mixture of grasses and legumes is desirable not only because of the higher nutritive value of the mixtures but also from the standpoint of benefiting the soil. Carpet grass and centipede grass under favorable soil and climatic conditions produce so close a turf as to drive out all the clovers and lespedezas that may have been seeded with them. Bromegrass in the Dakotas and southern Canada has been condemned by some because of its tendency to become sod-bound and because it reappears in a field that has been plowed for the production of a cash crop. Thus in some cases breeding methods must be used to reduce aggressiveness and in others to increase it.

INCREASED VIGOR AND QUICK RENEWAL OF GROWTH AFTER DEFOLIATION

The ability to renew growth quickly after defoliation is important.  Grasses are of low value in pastures or on ranges unless they are able within a reasonable time to replace by new growth the herbage removed by the grazing animal. Our best hay plants, such as alfalfa, are high producers because, after cutting and removing one crop of hay, new shoots appear immediately and grow as rapidly as the original stems, thus providing from two to eight cuttings a year. Among the grasses Sudan grass is a conspicuous example of a hay and pasture plant that comes back quickly after being cut or grazed  The extent and rapidity of growth in all plants is of course limited by soil and climatic conditions. Without a productive soil and adequate moisture supply either through rains or irrigation, continued luxuriant growth throughout the growth season is impossible. Fundamental differences however occur in the growth habits of plants that determine their behavior when clipped or grazed. Grasses that do not continually produce new growing points low down near the surface or underneath the surface of the soil are useless for lawns or golf courses because the turf becomes stubbly after it is clipped a few times. Hay plants that do not have a succession of buds at the crown capable of producing new shoots seldom produce more than one hay crop each season. The variation in these essential growth habits within a single species is marked and presents a good opportunity for improvement by selection processes.

PERSISTENCE OR LONGEVITY FUNDAMENTAL IN PASTURE GRASSES

Longevity under grazing conditions may be less important in the future than it has been in the past because of the present tendency to appreciate and demand high production in pastures. However, there will always be a large percentage of livestock producers who are willing to accept mediocre production from pastures and ranges in return for the assurance that this production level will continue indefinitely and reseeding will not be necessary. In some localities, like the semiarid regions, where the establishment of a satisfactory grass cover is difficult or highly uncertain, permanency may be the controlling factor in choosing a grass. Several factors such as drought resistance and winter hardiness have an important bearing on the longevity of a grass.  In breeding, therefore, longevity must be considered as a complex of several factors rather than a single one.

Drought resistance in plants has been the subject of much study in the arid and semiarid regions. It is not due to a simple Mendelian factor inherited as a unit character. Breeding for increased drought resistance will require a thorough understanding of the elements in plant composition and structure that enable certain plants to persist and produce better than others under low rainfall conditions.

TOLERANCE TO WET OR SALINE SOILS

In the United States considerable areas of wet lands occur. Some of these overflow at more or less regular intervals; other areas have a high water table or are continually saturated by the seepage of drainage water from the land above them. In irrigated areas benchland ditches often produce seepage areas in the bottom lands below them, and such areas are frequently both wet and saline (alkaline). Poorly drained lands in arid sections are almost invariably unproductive because salts accumulate in the surface layer through evaporation.

Certain species of grass are known. to be adapted to wet soils, and other species are especially tolerant of soil salinity. In both cases, however, these grasses are usually of low palatability and often of low nutritive value. A very real need undoubtedly exists for improvement of these grasses in palatability and nutritive value as well as for the development of strains with increased tolerance for the abnormal quantity of water or salts that such soils contain.

INCREASING PALATABILITY OR NUTRITIVE VALUE DIFFICULT

Grasses adequate as forage for farm animals must be both palatable and nutritious, To increase either the palatability or nutritive value of a grass is perhaps the most difficult of all the breeding problems.  The qualities that make a grass palatable are little understood, and the variations in nutritive value as indicated by chemical composition are slight within any one species. There is, therefore, little encouragement to attempt an improvement in these fields except by hybridization.

QUALITY, DURABILITY, AND UNIFORMITY IN TURF GRASSES

Considerable success has already been achieved in selecting strains of bentgrasses that meet the special needs of the golfing public. For the putting greens of golf courses both fine texture and uniformity are required (fig. 12); otherwise the path of the putted ball will be uncertain. Disease resistance, longevity, and aggressiveness are factors of great importance on both golf courses and lawns in order that the turf may be permanent and free of weeds and weedy grasses.


Figure 12.—A turf plot of Metropolitan bentgrass illustrating the fine texture and uniformity required for the putting greens of golf courses.

On athletic fields and playgrounds, and especially on airports, durability is the first consideration. A satisfactory turf for such purposes must be able to withstand the tearing and gouging of cleated or spiked shoes and the terrific impact of the landing gear on airplanes. To do this the grass must be deep-rooted and tough and also able to cover quickly gashes made in this way with spreading stolons or rhizomes.

CURRENT BREEDING WORK, ITS OBJECTIVES AND RESULTS

SELECTIVE BREEDING OF GRASSES IN THE UNITED STATES AND CANADA

Replies to questionnaires on grass breeding submitted to various agricultural institutions reveal the fact that selection for improvement is under way with a large number of grasses other than timothy.  Limited and more or less desultory activities in this field have been in progress for 16 years or more, but organized and intensive grass-breeding activities, for the most part, have been inaugurated within the last 5 years. The various grasses included in the current selective breeding programs of State and Federal institutions in the United States and Canada are listed in table 2. It is apparent that a considerable number of workers are now concerned in developing superior pasture and turf grasses. The results accomplished by selective breeding in foreign countries other than Canada are not discussed in detail because of the limitations of space and the fragmentary information obtained in response to the questionnaires. We have also to consider the fact that very few of the improved strains of grasses developed in Europe, Australia, or New Zealand have shown outstanding value in the United States. In Canada, however, the species under investigation are the same as those in the United States and climatic conditions are similar to those in our Northern States, hence results there should be helpful to our plant breeders. The locations of experiment stations in the United States and Canada where organized grass-breeding work is in progress are shown on the map in figure 13.


Figure 13.—Locations of experiment stations in the United States and Canada where organized grass-breeding work is in progress.

Improved or Elite Strains Developed by Selection

In the United States very few improved strains have yet been introduced into cultivation, but notable progress has been made, especially in the fine-turf grasses. The new strains already introduced, or soon to be ready for introduction, include:
   Washington and Metropolitan bent grass: These two strains of creeping bent grass developed by the green section of the United States Golf Association have replaced other grasses on a large percentage of the putting greens of golf courses throughout the country.  The fact that these turf grasses, when used on putting greens, are usually propagated vegetatively makes it easy to keep the strains pure and preserve their identity.

Velvet bent grass, strain F. C. 14276: This has shown marked superiority over the ordinary strain of velvet bent grass in vigor, disease resistance, and quality of turf.

Promising turf strains of Poa pratensis and P. trivialis have also been developed by the green section of the United States Golf Association, but these are not yet ready for distribution.

H. A. Schoth, of the United States Department of Agriculture, operating with the Oregon Agricultural Experiment Station at Corvallis, Oreg., has several improved strains ready for distribution.

Highland Reed canary grass: This is definitely superior on upland soils; it is a heavy seed producer, and the seed shatters less freely that of the ordinary strain.  Seed of this improved strain is now being produced and marketed commercially.

Tall fescue, strain F. C. 29366: This has softer or less harsh leaves than the ordinary tall fescue and in general improved quality of foliage and better seeding habits. Seed production of this tall fescue will be on a commercial basis in 1937.

Tall oatgrass, strain F. C. 29367: The fault of seed-shattering characteristic of this species has been remedied almost completely. In this strain the seed increase is just in the initial stages, so that it is not ready for commercial distribution.

Bahia grass, strain F. C. 19774: A selection made in 1929 by F. H. Hull, associate agronomist, Florida Agricultural Experiment Station, Gainesville, Fla., on the basis of stigma color has proved definitely more resistant to the helminthosporium leaf disease than the ordinary strain. This selection has been compared with the common strains of Bahia grass by George E. Ritchey, of the United States Department of Agriculture, at the Florida station. Arrangements are being made to increase the seed of it in Arizona as a source of commercial seed production.

Tift Bermuda grass: A vigorous, fine-stemmed strain selected by J. L. Stephens, of the United States Department of Agriculture, at the Georgia Coastal Plain Experiment Station, Tifton, Ga. This strain is much more productive as a hay plant than the common Bermuda grass. In 1936, when 400 pounds per acre of complete fertilizer Were applied, 2 tons per acre of fine quality hay were obtained in two cuttings. In the past it has been propagated vegetatively, since Bermuda grass does not produce viable seed in Georgia, at least in any quantity.

Reed canary grass, Iowa 503: This was selected by H. D. Hughes and F. D. Wilkins, agronomists at the Iowa Agricultural Experiment Station, from the progeny of seed sent to them by an Iowa farmer in 1918. The strain produces high yields of both hay and seed and appears valuable also in pastures because it makes a rather dense turf and remains green late in the fall. It was distributed to farmers in 1930 under the name Iowa Phalaris.

In Canada, where agricultural workers have devoted more attention to breeding problems, a considerable number of improved forage and turf strains have been developed and are now in commercial production. Among those reported by Canadian workers are the following:
   Grazier slender wheatgrass: A leafy uniform strain that produces a high yield of pasturage and hay. Developed by G. P. McRostie and L. E. Kirk at the Central Experimental Farm, Ottawa, Ontario.

L. E. Kirk, before his removal to Ottawa, and T. M. Stevenson, working at the Dominion Forage Crops Laboratory, Saskatoon, Saskatchewan, developed four elite strains or varieties, namely:
   Mecca slender wheatgrass: A high-yielding hay variety.
   Fairway crested wheatgrass: A rather dwarf, fine-stemmed, leafy strain that usually produces lower yields of hay than ordinary crested wheatgrass but is superior to the latter for use on lawns and on the fairways of golf courses. Already the Fairway strain has a wide use in the western parts of the United States and Canada.
   Superior bromegrass: This was developed by Kirk from material collected by J. Bracken prior to 1921.  It is now definitely established as a high-yielding hay and pasture variety.
   Parkland bromegrass: Characterized by a reduced rhizome development that makes it to all intents and purposes a noncreeping variety. Parkland bromegrass does not become sod-bound so quickly as ordinary bromegrass and is less difficult to eradicate when grown in rotation with cultivated crops.

O. McConkey
Figure 14.—O. McConkey, associate professor, Department of Field Husbandry, Ontario Agricultural College, Guelph, Ontario, Canada, who, with L. E. Kirk, of Ottawa, has pioneered in grass-breeding investigations in Canada.

Fyra slender wheatgrass:  This was developed by M.O. Malte and G.H. Cutter at the University of Alberta, Edmonton, Alberta, as an improved hay variety.

Avon orchard grass: Developed by workers in the Agronomy Department of MacDonald College at Quebec, this strain had its origin in foundation stock introduced by L. S. Klinck, 1911-14. Selfed lines were isolated by L. A. Waitzinger, G. P. McRostie, and A. MacTaggart in the period 1914-30, and J. N. Birdin subsequent years has combined the most promising of these genotypes to form the strain called Avon. The Avon is decidedly more winter-hardy and therefore longer lived and produces larger yields of hay and aftermath than commercial orchard grass. Increased seed production of the Avonisin progress at MacDonald College.

In addition to the named strains herein credited to Canadian breeders, O. McConkey (fig. 14) and his associates at the Ontario Agricultural College, Guelph, report (Y. B. Q.)9 that 23 improved strains of grasses are being increased for more extended trials and distribution at Guelph. These include the species listed for Guelph in table 1.

Reservoirs of Plant Material for Selection

The most important sources of material for selection are, of course, the ranges, pastures, and meadows where grasses have been established for a good many years. From this primary source and from foreign lands the United States Department of Agriculture in cooperation with State experiment stations has brought together for comparison in grass nurseries extensive collections of native and introduced species. Seed of all the more important native grasses collected by the Soil Conservation Service in 1935 and 1936 throughout the arid and semiarid Western States. Seed or propagating material of foreign species has been obtained through the Division of Plant Exploration and Introduction of the Bureau of Plant Industry for many years, and these and the native species are available to plant breeders in nurseries (fig. 15) maintained at field stations of the United States Department of Agriculture and at State experiment Stations and substations where cooperation with the United States Department of Agriculture exists. Such cooperation is indicated in table 1.


Figure 15.—Grass nursery maintained by the Bureau of Plant Industry and the Soil Conservation Service of the United States Department of Agriculture at the Northern Great Plains Field Station, Mandan, N. Dak. Side-oats grama in the middle foreground.

SELECTIVE BREEDING IN FOREIGN COUNTRIES OTHER THAN CANADA

Breeding work with grasses has been developed much more in the British Isles, New Zealand, Australia, Sweden, Germany, and Denmark than in the United States.

   The Imperial Bureau of Plant Genetics, Aberystwyth, Wales, has made the greatest contribution in the work on herbage grasses, under the direction of R. G. Stapledon. The technique for producing and distributing improved strains of grasses that has been developed by Stapledon and his associates, especially T. J. Jenkin (fig. 16), should be very helpful in formulating a program for similar work in the United States. It is described fully in a publication of that bureau (11).

The results achieved in the British Isles and New Zealand also provide proof of the practical value of a comprehensive grass- breeding program. Levy (18) agrostologist, New Zealand Department of Agriculture, reports progress in the use of improved strains of perennial ryegrass as follows: "The North Island is using over 95 percent certified (seed) and it is difficult to dispose of uncertified at any price.”

While the work at the Welsh Plant Breeding Station and in New Zealand is perhaps most outstanding, excellent breeding work has long been under way at the Northumberland County Agricultural Experiment Station at Cockle Park near Newcastle, England; at the Scottish Plant Breeding Station near Edinburgh, Scotland, and in South Africa and Australia.  A. Muntzing, of the Seed Control Station, Swedish Seed Association, Svalöf, Sweden; H. Weller, Weihenstephan near Munich, Germany; and H. N. Frandsen, Stoftegaard, Denmark, are also making valuable contributions in grass improvement and breeding technique.


Figure 16.—T. J. Jenkin, who is associated with R. G. Stapledon at the Welsh Plant Breeding Station and has made many important contributions to the science and art of grass breeding. He is responsible for the breeding of all grasses except orchard grass and for the development of a breeding technique.

The map in figure 17 gives the locations of foreign grass-breeding stations.


Figure 17.—Locations of the principal grass-breeding stations in the Eastern Hemisphere 1, Welsh Plant Breeding Station, Aberystwyth, Wales; 2, Northumberland County Agricultural Experiment Station at Cockle Park, near Newcastle, England; 3, Scottish Plant Breeding Station, near Edinburgh, Scotland; 4, Rijksstation voor Plantenveredeling, Ghent, Belgium; 5, Landessaatzuchtanstalt, Weihenstephan, near Munich, Germany; 6, Danish Plant Breeding Station, Stoftegaard, Denmark; 7, Seed Control Station, Swedish Seed Association, Svaléf, Sweden; 8, Institute of Plant Industry, Leningrad, Union of Soviet Socialist Republics; 9, Institute for Fodder Crops, Moscow, Union of Soviet Socialist Republics; 10, Central Asia Scientific Research Institute of Plant Protection, Tashként, Union of Soviet Socialist Republics; 11, Waite Agricultural Research Institute, Adelaide, Australia; 12, Commonwealth Council for Scientific and Industrial Research, Canberra, Australia; 13, Plant Research Station, Department of Agriculture, Palmerston North, New Zealand; 14, Canterbury Agricultural College, Lincoln, Canterbury, New Zealand; 15, Prinshof Pasture Research Station, Pretoria, South Africa.

PROGRESS IN HYBRIDIZATION OF GRASSES

Improvement by selection within a species or variety is usually the first step in a breeding program. In every crop, however, the plant breeder ultimately resorts to hybridization as a means of inducing greater variation and also in order to combine in one plant the desirable characters found in different species or genera‘of plants. The question of how soon hybridization should become a part of a breeding program is not an easy one to answer. Many believe crossing of species and genera should not be undertaken until the possibilities of improvement by selection have been virtually exhausted and approximately pure lines have been obtained for use as parents of the cross.  Several potent reasons exist for earlier use of this effective method of plant improvement: (1) To wait until the possibilities of selection are exhausted would delay hybridization benefits almost indefinitely; (2) strains developed by hybridization usually show more marked difference from the ordinary strain than do selections and are therefore easier to identify and keep pure in commercial trade channels; and (3) the intelligent combining of desirable traits, such as disease-resistance, with good forage characters, is often possible by crossing.

Breeders have successfully crossed many species of grasses and in several instances have been able to combine closely allied genera.  For the information of present and future workers in this field the hybrids between species are listed in table 3 and the hybrids between genera in table 4 in the appendix. It will be noted that a large proportion of these hybrids are the products of foreign workers, Russian plant breeders having been especially active in this field. A number of the hybrids are combinations of the relatives of wheat and rye.


Figure 18.—Triticum-Agropyron hybrid produced by W. J. Sando, United States Department of Agriculture, showing the hybrid vigor attained in the first generation.  From left to right, Agropyron elongatum, hybrid, Triticum aestivum.

Some of these, especially the Triticum-Agropyron hybrids, appear to ave marked forage value (fig. 18). Sando, of the United States Department of Agriculture, and Armstrong, of the Canadian Department of Agriculture, who have had an opportunity to observe such hybrids, are convinced that many of the segregates of these crosses will have great value from a forage standpoint. Armstrong (1) states in his report:  "Their [the Russian plant breeders] chief aim has been the creation of new forms of perennial wheat. For Canadian conditions the possibilities of obtaining new forms of forage crops by this method appear more attractive."  Arrangements are now being made by the United States Department of Agriculture to study the forage value of Sando’s crosses.


Figure 19.—A few of the variants found in the first-generation hybrid of a cross Poa arachnifera X pratensis: A, Texas bluegrass type; B, C, and D, intermediate types, C, being one of the less desirable; E, Kentucky bluegrass type.

Jenkin, of the Welsh Plant Breeding Station, has successfully crossed the two genera Festuca and Lolium and has also made many hybrids among the species within these genera. Brief notes on the progeny characters of these hybrids will be found in tables 3 and 4. No new strain of superior value has resulted from these crosses to date, and Jenkin reports that more immediate improvement in forage value can be attained through selection within a species than in the progeny of the crosses he has made.


Figure 20.—Single plants representing the various types found in the first generation of a cross Poa arachnifera X pratensis. These plants were grown on the United States Department of Agriculture grounds in 1909 from seed of crosses made by George W. Oliver the previous year.

This evidence of the futility of hybridization methods cannot be accepted as final, however. In many instances repeated backcrossing has been found necessary to produce the desired types. Muntzing, of the Swedish Seed Association, found in the progeny of a backcross (Dactylis glomerata x aschersoniana x glomerata) individuals more vigorous than D. glomerata. Texas bluegrass (Poa arachnifera) is dioecious, having the male and female spikelets on different plants. Using the pistillate plants as the female parent, E. Marion Brown, of the United States Department of Agriculture, made crosses of this species and Kentucky bluegrass at Columbia, Mo. He reports wide variation (fig. 19) in the first-generation plants, including individuals more resistant to heat and drought and more productive than Kentucky bluegrass. This cross was made first in 1908 by the late George W. Oliver. Oliver also found an unusual degree of variation (fig. 20) in the first-generation hybrid of this cross, but there was little interest in grass breeding at that time and nothing came of it. These results, in addition to the observed forage value of the Triticum-Agropyron hybrids, encourage further hybridization efforts.

GRASS GENETICS AND HYBRIDIZATION TECHNIQUE10

TO ACHIEVE the utmost possible success in breeding within any group of crop plants, a thorough understanding of the genetics of the plant species is necessary. It is a fact that a large number of the improved varieties that find their way into commercial channels are produced by the selection of existing variants or by breeders who consciously combine the desirable qualities of several varieties or species by crossing or hybridizing them without having any definite knowledge of the manner in which the desired character is inherited.  The genetic analysis of any species of plants or animals is extremely slow work, and many of the results obtained have no practical application. Individuals who accomplish most in the realm of pure genetics are not likely to be concerned overmuch as to whether new and improved crop varieties result directly from their research. Practical plant breeders are, however, impatient of delay and usually proceed without knowing quite what to expect in the progeny of a hybrid but fully convinced that something good will be found in the segregates if the parents of the cross have been intelligently chosen. With the grasses as with corn and wheat the more or less unscientific breeding operations have preceded the genetic investigation. Henceforth the two phases of breeding will no doubt progress together. As specially trained groups of geneticists become interested in the study of forage grasses, the fund of basic information regarding their genetic constitution will increase rapidly. At present it is most inadequate. We do, however, have some knowledge of certain characteristics of our more important grasses that are useful in genetic studies. These will be discussed briefly.


Figure 21.—Phalaris truncata, a foreign relative of the reed canary grass having a spikelike panicle.  Note the progress of blooming from apex to base.  Panicle on left began to bloom 2 days earlier than that on the right.

FLOWERING HABITS OF GRASSES

The inflorescence or flower-bearing organ of grasses may be a compact spikelike panicle as in canary grass or a more or less loose panicle as in orchard grass or bluegrass (figs. 21 and 22). Regardless of the type of inflorescence, flowering begins near the apex of the inflorescence and progresses more or less regularly toward the base. In the spikelet the reverse is true; the basal florets open first, followed in regular order by those above. Through the courtesy of Mrs. Agnes Chase, of the Division of Plant Exploration and Introduction, Bureau of Plant Industry, the essential floral organs, the floral envelope, and the arrangement of florets in the spikelet are shown in figure 23.


Figure 22.—Flowering panicle of Kentucky blue grass, illustrating the loose, open type of inflorescence found in many grasses.

Grasses flower, that is, extrude their stamens and liberate pollen, most abundantly in the early morning. This is an almost universal rule (3), although the period of flowering may be delayed and prolonged by cloudy atmospheric conditions.  For several grasses at least there is apparently a secondary, less intensive anthesis period in the afternoon. Fruwirth (5), who from 1906 to 1915 conducted some important and rather extensive studies of anthesis and pollination in grasses, reports a secondary blooming period in the afternoon that lasted only 1 or 2 hours. This work was conducted at Hohenheim and Waldhof, near Amstettin, Germany. Sando11 found in Agropyron longatum the maximum anthesis between 6 and 8 a. m., but there was another period of activity between 3 and 4 p. m. “No blooming occurred between 8 a. m., and 3 p. m.” Sando also reports that blooming is most active when the sun is shining and the temperature 70° F. or above. No blooming was ever observed at temperatures below 52°. He believes the delay or reduction in anthesis caused by a cloudy sky is due more to the lowering of temperatures than to increased humidity.


Figure 23.—A grass inflorescence is composed of spikelets, florets, and flowers: A, Generalized spikelet indicating the alternate arrangement of florets on the rachis and relative positions of the glumes; B, grass floret opened as at blooming time, showing how the lemma and palea are forced open by the lodicules; C, typical grass flower showing the essential floral organs necessary in fertilization.

The views of Sando respecting the effect of humidity are confirmed by the studies of Stephens and Quinby (29) on sorghum (Sorghum vulgare). They concluded, “Relative humidity apparently did not influence the time of blooming.” Since sorghum is a grass, it is interesting to note that under field conditions at Chillicothe, Tex., the rate of blooming in the sorghums was highest shortly after midnight rather than in the early morning as Sando found for his Agropyron and Triticum species growing in the greenhouse. Although the hour of maximum blooming activity in sorghum varied with varieties, Stephens and Quinby state, "A relatively small proportion of flowers opened before 10 p. m. or after 8 a. m., but there were no hours in which flowers were never found opening.” By placing plants in a dark room during the day and exposing them to artificial light at night the natural rhythm of blooming was reversed in 36 hours. It would appear, therefore, that light conditions are a most important factor in governing the time of blooming. They found, however, that lowering the temperature reduced the rate of blooming.

Fruwirth (5) agrees with Stephens and Quinby regarding the effect of humidity but not as to light. In an experiment with ryegrass and orchard grass in which he placed a box lined with black paper over the plants to exclude all light rays, he found that the plants bloomed in spite of the lack of light. He concluded from this experiment in which the heat was sufficient but light was lacking, that the latter seemed to be unnecessary for blooming. There is one criticism to be made of this experiment in that Fruwirth did not alternate darkness and light but left the box in place day and night. Recent investigations have emphasized the importance of the relative proportion of daylight and darkness in the reproduction processes of plant development.

Wolfe (38) in his studies of orchard grass at Blacksburg, Va., observed 76.9 percent of the flowers blooming from sunrise to noon, 6.6 percent from noon to sunset, and only 0.3 percent from sunset to midnight. The maximum blooming occurred from 8 to 9 a. m.

Jenkin (9) in 1921 observed for several grasses the time on "very fine days” [on both sides -ASC] when anthers were exserted under cool greenhouse conditions. These results show that the greater part of the blooming takes place in the forenoon. His recorded observations were as follows:

Lolium perenne.—Blooming period 9 a. m. to 11 a. m.; maximum 9:15 to 9:30 a.m.
Festuca rubra.—Blooming period 9:45 a. m. to 2:30 p. m.; maximum 12 to 1 p.m.
Alopecurus pratensis.—Blooming period 6 to 7:45 a. m.; maximum 6:30 to 7:30 a.m.
Phalaris arundinacea.—Blooming period 5 to 10:15 a. m.; maximum 6 to 6:30 a. m.

The author does not state in what month these observations were made. He does say, however, that in the open “These species apparently flower rather earlier while in dull weather in the greenhouse anther exsertion may be considerably delayed and * * * may be very poor for several days.” Jenkin found that orchard grass, tall oatgrass, and timothy, unlike the perennial ryegrass and red fescue, begin blooming early in the morning.

SELF-FERTILITY IN GRASSES AND ITS RELATION TO EFFECT OF INBREEDING

The fertility of many important grass species has been summarized in great detail by Beddows (3), of the Welsh Plant Breeding Station, who made a thorough review of the literature on this subject. He found that as a general rule the annual grasses were "highly self-fertile”, but the perennials showed a high degree of self-sterility.  Exceptions occurred however, in both cases, and in certain species there was a marked variation in respect to this character within the species. Nilsson (21), of Sweden, made a detailed study of fertility and the effect of inbreeding in meadow fescue, orchard grass, and timothy. As would be expected, the effect of close fertilization or inbreeding varies in different species according to whether they are really cross-fertilized or self-fertilized. The situation regarding these characters as they affect a few of our more important grasses will be found useful in breeding by either selection or hybridization methods.

Orchard grass or cocksfoot (Dactylis glomerata): Stapledon (27) found D. glomerata normally setting much more seed when cross-fertilized than when self-fertilized, but containing “representative plants which are highly self-fertile.” These results have been confirmed by breeders in the United States and Canada. Stapledon says, “There is every reason to suppose that completely self-fertile, single plant lines could be isolated.” Regarding loss of vigor from breeding he concludes that on the average selfed plants are about half as vigorous as plants produced by crossing. He found, however, certain “robust” plants that showed little loss in vigor when selfed for five generations. There is, therefore, an opportunity to use inbreeding methods on this species to purify lines.

Perennial ryegrass (Lolium perenne): Jenkin (10) and Gregor (7) report a low degree of self-fertility in L. perenne, but great variation between plants in this respect. Some plants were completely male-sterile while others were comparatively self-fertile, so that Jenkin (10) includes "breeding for self-fertility would not be a difficult matter" in perennial ryegrass. Beddows (3) reports 3.6 times as much seed produced in open-fertilized as in close-fertilized plants.

Loss of vegetative vigor resulting from continued inbreeding of unselected perennial ryegrass plants is extreme. Jenkin (11) reports an average loss of vigor approximating 63 percent when plants were selfed or fertilized with pollen from other plants of the same line. He concludes, "In perennial ryegrass loss of vigor from selfing is extreme, and consequently the results from other forms of inbreeding will also be relatively pronounced.” Wenholz and Whittet, of Australia (Y. B. Q.), confirm Jenkin’s results and have discontinued the practice selfing) in breeding perennial ryegrass.

Italian ryegrass (Lolium multiflorum): The conditions regarding fertility and loss of vegetative vigor are about the same in Italian as in perennial ryegrass.

Crested wheatgrass (Agropyron cristatum): White (Y. B. Q.), of Saskatchewan, reports that sterility is very marked in caged or bagged plants, although this evidence of self-sterility is not conclusive. He found also a large decrease of vegetative vigor in close-fertilized plants, which indicates a low degree of self-fertility.

Slender wheatgrass (Agropyron pauciforum): Malte (19), of the Central Experimental Farm, Ottawa, Ontario, Canada, reported in 1921 that A. pauciflorum (A. tenerum Vasey) was self-fertile, and White (Y. B. Q.) found this species almost completely self-fertile and showing no loss in vegetative vigor from continued selfing. This condition presents a strange contrast to the behavior of A. cristatum.  Beddows (3), of Wales, agrees with White, finding both A. repens and A. pauciflorum highly self-fertile.

Bentgrass (Agrostis spp.): North (Y. B. Q.), formerly of Rhode Island, reported A. alba (redtop) somewhat more self-fertile than A. tenuis (colonial bent), A. canina (velvet bent), or A. palustris Huds. (creeping bent). All of the Agrostis species showed a tendency toward loss of vigor from continued selfing although only a few generations were obtained.

Smooth bromegrass (Bromus inermis): White (Y. B. Q.) reports self-sterility “fairly marked" in bromegrass, but adds that there is a wide variation between plants. If this variation exists it would admit of the development of reasonably self-fertile strains. Beddows’ (3) results show a very high degree of self-sterility in B. inermis, but very little in B. catharticus (B. unioloides) and other annual bromes. White also reports a marked and progressive loss in vegetative vigor from selfing for four or five generations. This loss of vigor from selfing is confirmed by McConkey (Y. B. Q.), of the Ontario Agricultural College.

Reed or tall fescue (Festuca elatior var. arundinacea): Beddows (3) found 5.1 times as many seeds developing in open-pollinated as in close-pollinated inflorescences. Govaert (Y. B.Q.), of the Rijksstation voor Plantenveredeling, Ghent, Belgium, reports a wide variation between individual plants, some being almost completely self-fertile.

Meadow fescue (Festuca elatior var. pratensis): According to Beddows (3), the meadow fescue is more self-sterile than the tall fescue. Open-pollinated panicles gave 22.3 times as many seed as the close-fertilized ones. As in the tall fescue, however, Govaert (Y. B. Q.), of Belgium, found a wide variation in individual plants, the number of seeds on different plants varying from an average of less than 1 to 409 per inflorescence. There would seem, therefore, to be an opportunity here to select self-fertile strains. G. Nilsson- Leissner (Y. B. Q.), at the Swedish Seed Association, Svalsf, Sweden, found cases of complete self-sterility in meadow fescue and a marked loss of vigor after repeated selfing.

Red fescue (Festuca rubra): Beddows (Y. B. Q.) found the self- fertility in red fescue about as low as in tall fescue, selfed plants producing about one-fifth as much seed as those open-pollinated. G. Nilsson-Leissner (Y. B. Q.), of Svaléf, found cases of complete self- sterility and a marked loss of vigor caused by selfing, as he had in meadow fescue.

Canada bluegrass (Poa compressa): McConkey (Y. B. Q.), of the Ontario Agricultural College, reports this species largely self-fertile. Under such conditions there is probably very little decrease in vegetative vigor caused by selfing.

Kentucky bluegrass (Poa pratensis): A considerable number of plant breeders and cytologists have studied this important grass and found it unusually interesting from two angles—there is a wide variation in the number of chromosomes, and seed is produced, to a considerable extent at least, apomictically. Musser (Y. B. Q.), of Pennsylvania, Brown (Y. B. Q.), of Missouri, and others report no self-sterility in Kentucky bluegrass and no apparent loss of vigor from selfing.

Sudan grass (Sorghum vulgare var. sudanense): Sudan grass, a close relative of the cultivated sorghums, is self-fertile. Robertson (Y. B. Q.), of Colorado, reports no apparent loss of vigor after three generations of selfing. Wenholz (36, p. 83), of New South Wales, reports loss of vigor in some lines under continued inbreeding.

Fruwirth (5) reports a method of overcoming the handicap of self-sterility in the perennial grasses that may be of great value to plant breeders. He divided the clump or tuft that had developed from a single seed and grew these parts of the same plant to maturity in separate pots or boxes. When these individual plants were isolated as a group and allowed to bloom freely and interpollinate each other, considerable viable seed was produced. There were, however, some cases where this method was not successful. With “French ryegrass" no seed was obtained, and Fruwirth concluded that these plants were completely self-sterile.

SELF-STERILITY IN HYBRIDS

Self-sterility, or more properly male-sterility, in the F1 of interspecific and intergeneric grass hybrids is quite common (table 4). In many cases there is variation in the degree of sterility among individuals, but in most cases backcrossing is required to produce seed.  The number of self-fertile segregates increases with repeated backcrossing, which is an accepted procedure among breeders who are laboring to produce new varieties of value in practical agriculture.  In some cases polyploidy is induced and increased vigor obtained by crossing the hybrid with a third species.

Verushkine (35) reports that in general the fertility of the hybrids of Triticum and Agropyron exceed considerably the fertility of the rye-wheat hybrids, and that it is somewhat higher than the fertility of Aegilops X Triticum hybrids. He classifies the Triticum X Agropyron hybrids into the following groups in respect to the fertility of the first generation:

  1. T. vulgare12 X A. elongatum.
  2. T. durum X A. intermedium and A. trichophorum.
  3. T. vulgare12 X A. intermedium and A. trichophorum.
  4. T. durum X A. elongatum.

   No trouble is experienced in the first group in obtaining self-fertilized seed, but in the fourth group “among hundreds of plants”.  Verushkine and his associates found none self-fertile.

   Successful crosses of the two genera Festuca and Lolium are reported by T. J. Jenkin (see footnotes 1 and 3, table 4), of the Welsh Plant Breeding Station. In many cases although seed set, none of it germinated. In other cases F1 plants were established, but these were male-sterile. They were, however, in many cases used successfully as the pistillate parent in backcrosses on one of the parent species.

CHROMOSOME COMPLEX OF GRASSES

The basic chromosome number for grasses is usually seven. There are, of course, exceptions, like that of the Sorghum species, where the basic number is five. Cytologists have already determined the chromosome number in a large proportion of the grass species, and their summarized records are available to the plant breederin several publications. The most extensive lists of chromosome numbers in grasses are those of Avdulow (2), Gaiser (6), and Tischler (30). In order to make such data available to breeders in the United States, a condensed list of reported chromosome numbers in grasses is given in table 5.

No thorough investigation of the chromosome behavior during meiosis has been made for any of the forage grasses. A limited amount of information is available, however, regarding valence, lagging, etc, of the chromosomes of certain grasses. Wide differences in the chromosome numbers of individuals of certain species have been reported. These chromosome irregularities naturally affect the behavior of hybrids and in some cases are useful factors in maintaining the purity of selected strains. Thus in breeding orchard grass (Dactylis glomerata) the Ontario Agricultural College (23) found the leafy pasture strain had 14 chromosomes while the common commercial strain had 28 chromosomes. Therefore the two strains do not cross readily; each remains pure or distinct.

The pasture strain of orchard grass developed by selection in Ontario has 14 chromosomes, the same number as the so-called wild species Dactylis aschersoniana, according to Müntzing (20) of the Swedish Seed Association. Müntzing found natural crosses of D. glomerata and D. aschersoniana near Svalof, although it was found very difficult to make this cross artificially.  He found 21 chromosomes in the natural hybrid, and when this triploid was backecrossed on D. glomerata the F1 had 35 chromosomes. These pentaploids were more vigorous than ordinary orchard grass, and in their progeny individuals were found having 38, 39, and even 41 chromosomes. Peto (24), at the University of Alberta, in his very detailed cytological studies of the Agropyron species, reported 14 and 28 chromosome forms of A. cristatum and 21 and 28 chromosome forms of A. pauciflorum.

Randolph (Y. B. Q.), cytologist, Division of Cereal Crops and Diseases, Bureau of Plant Industry, at Cornell University, found in Kentucky bluegrass (Poa pratensis) individuals having 48, 50, 54, 68, and 72 somatic chromosomes. The most common number reported for P. pratensis is 56. Practically all cytologists who have worked with this species have noted wide variations. Since 7 is the basic chromosome number in most grasses, if this condition is a tendency toward polyploidy the differences should be various multiples of 7.  Randolph’s results previously mentioned and those of Rancken (26) may be explained on the basis that these indicated variations from exact multiples of 7 are the result of the cytologists’ failure to distinguish between whole chromosomes and fragments. These “supernumerary chromosome fragments” Rancken reports are present in Poa pratensis, Dactylis glomerata, Festuca elatior var. pratensis, and Alopecurus pratensis. Chromosome fragments, Rancken believes, may possibly act as phylogenetic factors.

A peculiar_chromosome relationship found in Phalaris species is reported by Jenkin and Sethi (15).  P. arundinacea and P. tuberosa both have 28 somatic chromosomes showing 14 bivalents in the heterotypic metaphase. The basic number in these species is obviously 7, but in P. canariensis the basic number is reported as 6.  P. arundinacea and P. tuberosa were successfully crossed and the F1 had 28 chromosomes, 12 bivalent and 4 univalent. Other instances of apparent aberrant chromosome conditions are recorded by cytologists, but those mentioned are sufficient to indicate the nature of such abnormalities in forage grasses.

The production of polyploidy or doubling of the chromosome number by means of species crosses is illustrated by the work of Nilsson (21), Undrom, Sweden, who reports as follows: “From the hybrid F. [Festuca] arundinacea X F. gigantea, which is highly sterile, 2 progeny plants were obtained.  F1 had the same somatic chromosome number (42) as the parents, but the progeny plants differed very much, one having the somatic number 84.” This doubling of the chromosmes is explained to have originated by accidental intercrossing of the F1 hybrid and a third species, F. elatior var. pratensis. Such an explanation is said to be in harmony with the morphological characters. The author claims this has resulted in “a new polyploid type intermediate between the parents and highly fertile in comparison with F1.”

COMPATIBILITY A FACTOR IN HYBRIDIZATION

   As hydridization investigations progress it is apparent that there are different degrees of compatibility not only between species but also between varieties and even strains. Thus Armstrong (1), when using Agropyron glaucum as the pollen parent, was 32.2 to 34.6 percent successful with Triticum durum and T. dicoccum, respectively, as the pistillate parents and only 6.5 to 11.7 percent successful with three varieties of A. aestivum as the pistillate parent. Strain no. 820 of A. elongatum crosses on emmer (A. dicoccum) resulted in 38.7 percent success, while strain no. 1083 crossed with emmer gave only 1.5 percent success.

   Most workers have found a high degree of compatibility between Triticum aestivum and Agropyron elongatum and between T. durum are T. dicoccum and A. intermedium. A. trichophorum and A. junceum are also said to cross readily with wheat, but no one has been able to cross wheat with A. repens, and Sando reports failure in his attempts to cross wheat and A. smithii. Armstrong (1) and other Canadian workers have failed in their attempts to use as the pollen parent A. desertorum, A. dasystachyum, A. caninum, A. imbricatum, A. repens, A. cristatum, or A. richardsoni in crosses on T. durum, T. dicoccum, or T. aestivum. These unsuccessful attempts to combine the indicated species of Agropyron with the Triticum species, while not conclusive, are evidence of incompatibility not apparent, from morphological characters customarily used in botanical classifications. The examples given of differences between species of Agropyron and Triticum will serve to illustrate what the breeder may expect to encounter in other genera.

TECHNIQUE OF HYBRIDIZATION

   Jenkin, of the Welsh Plant Breeding Station, has, no doubt, studied this question to a greater extent than any other investigator. His recommendations (9) as to the best methods of crossing grasses are given in a bulletin published in 1924, and a later résumé (11) of the subject was published in 1931.

Geneticists usually agree that hand-crossing is the only method to follow if dependable results are to be obtained, and this is emphasized by Jenkin. He sets forth several rules to be observed in the work of hybridization:

  1. No inflorescence of a species used for crossing should be allowed to flower unprotected in the greenhouse. This is to avoid free pollen floating about.
  2. All ventilators should be closed an hour or more before starting operations, to prevent drafts and allow free pollen to settle and avoid scattering pollen that is being collected for use in crossing.
  3. Soft brushes should be used in applying pollen.
  4. On both the pistillate and the pollen parent inflorescences should not be exposed any longer than absolutely necessary.
  5. Each brush should be sterilized after being used, and a sufficient number of brushes should be available so that no brush will be used more than once a day.

Emasculation Methods and Equipment

Emasculation of all flowers left on the pistillate parent to be pollinated is necessary except when that parent is known to be completely male-sterile. This operation must perforce be performed before full bloom occurs, but it is most easily accomplished just prior to this stage of development. In sorghums the flowers may be successfully emasculated by immersing the inflorescence in hot water for a short time. This method, discovered by Stephens and Quinby (28), may perhaps be equally effective on the smaller grasses, but until the exact temperatures required to kill the pollen on these grasses without injuring the stigmas are determined, most breeders will continue to use the more tedious hand-emasculation method.


Figure 24.—Comparative size of florets of various grasses in comparison with the wheat floret: a, Wheat; b, smooth bromegrass; c, crested wheatgrass; d, orchard grass; e, woolly fingergrass; f, Kentucky bluegrass. X 9. Upper right natural size.

  The process of hand emasculation in grasses is very difficult owing to the small size of the individual florets (fig. 24). While Jenkin suggests emasculating with the naked eye or with the assistance of only a small hand lens, most breeders find magnifying instruments necessary or at least very helpful. Instruments for this purpose should be capable of use without being held in the hand, since both hands must be free to manipulate the flowers. Magnifying glasses provided with a contrivance to hold them in position on the operator’s head are preferred by some.  Others find binocular microscopes attached to a horizontal arm on a vertical stand of the proper height most satisfactory for this work (fig. 25). When the lenses are adjusted to a long focus there is little interference with the movements of the hands and the delicate emasculation operations may be carried out with more assurance than without such equipment. The use of a binocular in hybridization work with grasses was suggested in 1934 by De Villiers (4), research officer, Division of Plant Industry, Pretoria, South Africa. Much of his work was with the Digitaria species, or woolly fingergrasses, which have extremely small flower parts (fig. 24). Emasculation of such grass flowers without magnifying instruments is well-nigh impossible.


Figure 25.—A binocular microscope with horizontal arm adjustment as used in the emasculation of woolly fingergrass for cross-pollination in the greenhouse.

   The technique that Sando (Y. B. Q.) developed in the hybridization of Triticum and Agropyron species is applicable to other grasses.  The necessary operations are described as follows: In preparing a plant for hybridization, several upper and lower spikelets of the inflorescence are excised with a small scissors before blooming. Likewise all but the two lower florets of the remaining spikelets are removed.  Emasculation of these flowers is then effected with slender tweezers and the inflorescence enclosed in a glassine bag. Several days later, when the stigmas reach the stage of receptivity, the glassine bag is removed and pollinations are made, after which the bag is again replaced to remain until maturity.

In the transfer of pollen the most successful results have been accomplished by holding a sheet of clean paper beneath the blooming flowers and slightly shaking them to cause the anthers to expel their pollen. This pollen is then placed in a convenient ring receptacle (fig. 26), described in a previous publication (17). From this receptacle it is transferred with a pair of tweezers or otherwise to the stigmas of the flowers previously emasculated. The period of pollen production Sando finds can be extended considerably by the following practice: Holding a culm just below the inflorescence with the left hand, the head is stroked upward vigorously several times with the thumb and forefinger of the right hand. This induces the flowers to extrude their anthers, provided the temperature is favorable. Such artificial stimulation is most readily accomplished previous {to the active blooming periods rather than later. High humidity or rainfall causes the pollen to form a conglomerate mass through the absorption of moisture from the atmosphere. Such pollen is nonfunctional and therefore useless in hybridization.


Figure 26.—A handy pollen carrier devised by W. J. Sando, United States Department of Agriculture, consisting of an adjustable ring in which are inserted capsules that may be readily removed and discarded after the pollination process is completed.

Collecting the Pollen and Pollinating

It will be noted in the previous discussion that Sando applies the pollen with tweezers while Jenkin prefers to use a soft brush. In collecting the pollen also Jenkin merely shakes the bagged heads until all the pollen grains are detached from the anthers and then pours the pollen out of the bag on a sheet of paper previously creased so that it can be folded easily to collect the pollen in the middle of the sheet.

The time of day when anthesis takes place in various grasses has been discussed under flowering habits. When two species or two genera are being crossed, difficulty is sometimes encountered because the pollen parent does not reach the blooming stage at the same date as the pistillate parent. Some adjustment of the blooming period in most grasses may be effected by subjecting one or both parents to an artificial regulation of the day length. Sando (Y. B. Q.) used this method successfully to bring his Agropyron elongatum plants into bloom at the time his wheat plants were ready to cross-pollinate.

The length of time pollen grains will remain viable depends altogether on the conditions in which they are kept. When properly stored they have been known to remain viable several days, but the safest procedure is to apply the pollen immediately after it is gathered.  More latitude exists in respect to the receptivity of the stigmas.  Stephens and Quinby (29) report for sorghums that "stigmas were receptive at least 48 hours before the flowers bloomed and from 8 to 16 days after blooming.” Jenkin (9) reports for Lolium perenne that the stigmas were receptive in one case 13 days after emergence, but none were found receptive on the fifteenth day. It is apparent therefore that considerable time may elapse before pollen need be applied to the stigmas.

   While Jenkin advises repeated application of pollen, his data show as good results from two applications as from four or six. It would seem, therefore, that if the pollen is in good condition and is properly and thoroughly applied, one replication is sufficient.

Isolation Methods and Materials

When hybridization is being conducted in a greenhouse, ordinary glassine or waxed paper bags have proved satisfactory for isolating the inflorescences of parent plants. For field operations, however, Jenkin (11) found the glassine bags, as used in the greenhouse, useless, and ordinary parchment paper bags equally unreliable. Cloth bags woven in seamless pillowcase form and held in place by specially constructed frames proved most satisfactory. Extensive tests were made of various cotton fabrics, and it was found that many these did not fully prevent the passage of pollen grains.  However, Jenkin found a satisfactory standard fabric, the specifications of which are: Threads per inch—warp 68, weft 65; count—warp 2/32’s, weft 16’s.

   Cages are also used in the field to prevent unintended pollination, and special ventilated rigid boxes which may be adjusted over a single culm have been constructed and used by some breeders. The latter, however, are too expensive for extensive use. All experienced breeders agree that unless great care is used in bagging, the results of otherwise careful work may be vitiated by unfavorable conditions within the bag. Failure of bagged heads to produce seed is in many cases caused by these unfavorable conditions rather than by incompatibility of the parents.

INHERITANCE OF CHARACTERS

Only a very limited amount of data is available on this subject.  Those who have studied Triticum-Agropyron hybrids agree that the perennial nature of the Agropyron parent is dominant in the F1 hybrid.  The proportion of perennials quite naturally decreases rapidly in succeeding generations of backcrosses on the annual Triticum species, According to Verushkine (35), only 43 to 66 percent of the second generation plants are perennials. He remarks that the F, affords a wide segregation of characters and includes for the most part intermediate types.

Armstrong (1), of the Central Experimental Farm, Ottawa, Canada, agrees with Verushkine in general as to the dominance of the perennial character in the Triticum-Agropyron hybrids. He names several other Agropyron characters that are dominant, but finds a condition of intermediacy in respect to quantitative characters such as spike density, glume width, and leaf width and scabrousness. When awned wheats were used as the pistillate parent and A. glaucum as the pollen parent, the hybrids were awn-tipped, an intermediate condition. When A. elongatum was used as the pollen parent the hybrids were awnless in most cases. Both species of Agropyron are awnless.

The presence in Lolium multiflorum of a root substance that causes a fluorescence on filter paper when examined under ultraviolet light has been used to distinguish this species from L. perenne. Woodforde (39), of the Tasmanian Department of Agriculture, reports that this character is inherited as a simple Mendelian dominant dependent on a single factor. However, he found no genetic linkage between fluorescence and awned flowering glumes, a distinguishing character of L. multiflorum.

Jenkin (12), of the Welsh Plant Breeding Station, in a study of bulbous tall oatgrass, found in the F1 of a cross of the nonbulbous and bulbous forms an intermediate condition in respect to bulb development, although all F1 plants were definitely bulbous. In the F2 and F3 there was an apparent segregation for bulb development, which was hard to analyze, since a great majority of the plants were more or less bulbous. He concludes that more than one pair of factors is concerned in bulb development, and that the same is true of the hairiness of stem nodes, another distinguishing character of bulbous tall oatgrass. The value of this research lies in the fact that the bulbous form behaves as a weed in cereal fields under certain conditions, while the nonbulbous form does not.
LITERATURE CITED

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   (37)  Wiley, H. W. 1906. PRINCIPLES AND PRACTICES OF AGRICULTURAL ANALYSIS; A MANUAL FOR THE STUDY OF SOILS, FERTILIZERS, AND AGRICULTURAL PRODUCTS; FOR THE USE OF ANALYSTS, TEACHERS, AND STUDENTS OF AGRICULTURAL CHEMISTRY. V. 1, illus. Easton, Pa.
   (38)  Wolfe, T. K. . 1925. OBSERVATIONS ON THE BLOOMING OF ORCHARD GRASS FLOWERS. Jour. Amer. Soc. Agrow. 17: 605-618.
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APPENDIX
TABLE 1.—Development centers of important grasses useful in breeding*
RegionGrasses**
Common nameScientific name
(1) Europe, except the Mediterranean region and the eastern or dry portion of the Union of Socialist Soviet RepublicsRedtopAgrostis alba
BentgrassAgrostis spp.
BeachgrassAmmophila areanaria
Tall oatgrassArrhenatherum elatius
Awnless bromegrassBromus inermis
----------Dactylis aschersoniana
Cocksfoot or orchard grassD. glomerata
Reed or tall fescueFestuca elatior var. arundinacea
Meadow fescueF. elatior var. pratensis
Italian ryegrassLolium multifiorum
Perennial ryegrassL. perenne
Mountain timothyPhleum alpinum
----------P. boehmeri
TimothyP. pratense
Mountain bluegrassPoa alpina
Annual bluegrassP. annua
Canada bluegrassP. compressa
Kentucky bluegrassP. pratensis
Rough-stalked bluegrassP. trivialis
CordgrassSpartina townsendii
(2) Mediterranean region of Europe and AfricaGiant reedArundo donaz
Wild oats (annuals)Avena barbata, A. fatua, A. sterilis, A. strigosa
Bromes (annuals; cheat or chess)Bromus arvensis, B. mollis, B. secalinus, B. sterilis
Red fescueFestuca rubra
Canary grassPhalaris canariensis
Harding grassP. tuberosa
Esparto grassStipa tenacissima
(3) Eastern Union of Socialist Soviet Republics and SiberiaWheatgrassesAgropyron caninum, A. cristatum, A. elongatum, A. intermedium, A. trichophorum
ReedgrassesCalamagrostis spp.
Wild ryeElymus spp.
Sheep fescueFestuca ovina
RicegrassesOryzopsis spp.
Chee grassStipa splendens
(4)Southern Union of Soviet Socialist Republics, Turkistan, Sinkiang (China), Turkey, Palestine, and AfghanistanGoatgrassesAegilops crassa, A. cylindrica, A. ovata, A. squarrosa, A. triuncialis
Meadow foxtailAlopecurus pratensis
Sweet vernal grassAnthoranthum odoratum
Wild oatsAvena barbata, A. fatua, A. sterilis, A. strigosa
Red fescueFestuca rubra
Barley relativesHordeum species
Bulbous bluegrassPoa bulbosa
RyeSecale cereale
JohnsongrassSorghum halepense
Wheat relativesTriticum spp.
(5)Tibet, western provinces of China, and eastern MongoliaWheatgrassesAgropyron spp.
Wild-ryesElymus spp.
FescuesFestuca spp.
BluegrassesPoa alpina, P. attenuata, P. nemoralis, P. tibetica
NeedlegrassesStipa spp.
(6)Eastern Siberia, Manchuria, northeastern China, Chosen, and Japan----------Arundinella spp.
Manchu reedgrassCalamagrostis epigeios
Jungle riceEchinochloa colona
Japanese milletE. crus-galli
Broomcorn milletPanicum miliaceum
Foxtail milletSetaria italica
BristlegrassesSetaria spp
Japanese lawngrassZoysia japonica
Manila lawngrassZ. matrella
SorghumsSorghum vulgare
(7)India, southeastern China, Burma, Malay Peninsula, Sumatra, Java, Borneo, New Guinea, TaiwanAngleton grassAndropogon annulatus
Dwarf bambooBambusa nana
BambooB. vulgaris
“Doob” (Bermuda) grassCynodon dactylon
Finger milletsEleusine coracana
Centipede grassEremochloa ophiuroides
Cogon grassImperata cylindrica
RicegrassOryza sativa
Kutki milletPanicum psilopodium
Koda milletPaspalum scrobiculatum
Edible bambooPhyllostachys edulis
Sugarcane relativesSaccharum spp.
SorghumsSorghum vulgare
(8) Australia, New Zealand, and TasmaniaNative grasses (grown in dry areas):
Mitchell grassAstrebla pectinata
Curly Mitchell grassA. triticoides
Wallaby grassDanthonia semiannularis
Flinders grassIseilema membranacea
Australian tussock grassPoa caespitosa
New Zealand tussock grassP. flabellata
Silvery sandgrassSpinifer hirsuta
Kangaroo grassThemeda spp.
SpinifexTriodia spp.
Introduced grasses (grown where rainfall is adequate):
Rhodes grassChloris gayana
Orchard grassDactylis glomerata
Meadow fescueFestuca pratensis
Italian ryegrassLolium multifiorum
Perennial ryegrassL. perenne
Dallis grassPaspalum dilatatum
(9) Equatorial AfricaBluestem relativesAndropogon spp.
BrachiariasBrachiaria spp.
TeffEragrostis abyssinica
Carib grassEriochloa polystachya
Wild barleysHordeum spp.
----------Hyparrhenia spp.
Guinea grassPanicum mazimum
Para grassP. purpurascens
Bentham grassPennisetum benthami
Kikuyu grassP. clandestinum
Pearl or cattail milletP. glaucum
Merker grassP. merkeri
Napier or elephant grassP. purpureum
SorghumsSorghum vulgare
Grass sorghumsS. vulgare vars.
“Rooi gras” or red grassThemeda triandra
Herringbone grassUrochloa pullulans
(10) Africa south of 10° south latitude, which includes southern Angola and Tanganyika, all of Nyassaland, Mozambique, Rhodesia, Bechuanaland, South Africa, and MadagascarRhodes grassChloris gayana
“Kweek” (Bermuda) grassCynodon dactylon
Red kweek grassC. hirsutus
Woolly fingergrassDigitaria eriantha stolonifera
Other fingergrassesDigitaria spp.
----------Ehrharta calycina
----------Hyparrhenia spp.
SorghumsSorghum vulgare
Grass sorghumsS. vulgare vars.
"Rooi gras" or red grassThemeda triandra
Natal grassTricholena rosea
(11) Brazil, eastern Bolivia, Paraguay, Uruguay, and northeastern ArgentinaCarpet grassAzonopus compressus
Pampas grassCortaderia selloana
Jaragua grassHyparrhenia rufa
Molasses grassMelinis minutifiora
RiceOryza sativa
Guinea grassPanicum mazimum
Bahia grassPaspalum notatum
(12) Andean region of Peru, Bolivia, Chile, and Argentina“Maicillo” or "cachi"Azonopus scoparius
ReedgrassesCalamagrostis spp.
FescuesFestuca spp.
Muhly grassMuhlenbergia spp.
BluegrassesPoa spp.
(13) Southern Mexico, Central America, northwestern South America, and the West IndiesGiant reedArundo donaz
Carpet grassAzonopus compressus
“Malojilla” or Carib grassEriochloa polystachya
TeosinteEuchlaena mezicana
Mexican teosinteE. perennis
Wild riceOryza latifolia
Guinea grassPanicum maximum
Para grassP. purpurascens
Bahia grassPaspalum notatum
St. Augustine grassStenotaphrum secundatum
Eastern gamagrassTripsacum dactyloides
Long-leaved gamagrassT. latifolium
Guatemala grassT. laxum
Corn (maize)Zea mays
(14) Great Plains and inter-mountain regions of North AmericaNative grasses:
Thickspike wheatgrassAgropyron dasystachyum
Slender wheatgrassA. pauciflorum
Streambank wheatgrassA. riparium
Bluestem (western wheatgrass)A. smithii
Bluebunch wheatgrassA. spicatum
Bearded wheatgrassA. subsecundum
Big bluestemAndropogon furcatus
TurkeyfootA. hallii
Silver beardgrassA. saccharoides
Little bluestemA. scoparius
Six-weeks gramaBouteloua barbata
Crowfoot gramaB. chrondrosioides
Side-oats gramaB. curtipendula
Black gramaB. eriopoda
Hairy gramaB. hirsuta
Rothrock gramaB. rothrockii
California bromegrassBromus carinatus
Buffalo grassBuchloë dactyloides
Pine grassCalamagrostis rubescens
Long-leaved sandgrassCalamovilfa longifolia
Canada wild-ryeElymus canadensis
Giant wild-ryeE. condensatus
Beardless wild-ryeE. triticoides
Virginia wild-ryeE. virginicus
Bluebunch fescueFestuca idahoensis
Six-weeks fescueF. octoflora
Sheep fescueF. ovina
Red fescueF.rubra
Greenleaf fescueF. viridula
Curly mesquiteHilaria belangeri
Galleta grassH. jamesii
JunegrassKoeleria cristata
SwitchgrassPanicum virgatum
Canby bluegrassPoa canbyii (P. laevigata)
Nevada bluegrassP. nevadensis
Sandberg bluegrassP. secunda (P. sandbergii)
Nutall alkali grassPuccinellia nuttalliana
Blowout grassRedfieldia fleruosa
Indian grassSorghastrum nutans
Alkali sacatonSporobolus airoides
Sand dropseedS. cryptandrus
SacatonS. wrightii
Long-awned spear grassStipa comata
Introduced grasses:
Crested wheatgrassAgropyron cristatum
Awnless bromegrassBromus inermis
Bulbous bluegrassPoa bulbosa
Sudan grassSorghum vulgare var. sudanense
(15) Southeastern Canada northeastern United StatesNative grasses:
QuackgrassAgropyron repens
American beachgrassAmmophila breviligulata
Big bluestemAndropogon furcatus
Little bluestemA. scoparius
BluejointCalamagrostis canadensis
Virginia wild-ryeElymus virginicus
American mannagrassGlyceria grandis
SwitchgrassPanicum virgatum
Reed canary grassPhalaris arundinacea
Smooth cordgrassSpartina alterniflora
Big cordgrassS. cynesuroides
Saltmeadow cordgrassS. patens
Prairie cordgrassS. pectinata
Eastern gamagrassTripsacum dactyloides
Wild riceZizania aquatica
Introduced grasses (see also list for region 1):
Japanese milletEchinochloa crus-galli var. frumentacea
Foxtail milletSetaria italica
(16) Southeastern United StatesNative grasses:
Southern caneArundinaria gigantea
Small caneA. tecta
Virginia wild-ryeElymus virginicus
Texas bluegrassPoa arachnifera
Smooth cordgrassSpartina alterniflora
Big cordgrassS. cynosuroides
Saltmeadow cordgrassS. patens
Southern cordgrassS. spartinae
Eastern gamagrassTripsacum dactyloides
Southern wild riceZizaniopsis miliacea
Introduced grasses:
Carpet grassAzonopus compressus
Rescue grassBromus catharticus
Bermuda grassCynodon dactylon
Centipede grassEremochloa ophiuroides
Para grassPanicum purpurascens
Dallis grassPaspalum dilatatum
Bahia grassP. notatum
Vasey grassP. urvillei
Pearl milletPennisetum glaucum
Napier grassP. purpureum
Japanese caneSaccharum chinense
Johnson grassSorghum halepense
Natal grassTricholaena rosea
*Numbers of regions correspond to those in fig. 1.
**In naming the grasses characteristic of a region no attempt has been made to restrict them to native species, since in certain areas the introduced species are more abundant and more important than the native ones.  Some grasses, omitted because of their apparent lack of usefulness, are more widely distributed and more characteristic of a region than are any of the species named.  It should be understood also that in most cases other species of the genera listed occur in the region.


TABLE 2.—Objectives and progress in the selective breeding of grasses as reported by workers in the United States and Canada
LocationψIndividual workersGenera and speciesPeriod work under wayObjectivesSuccess attained
UNITED STATES
Arizona:  Tucson*E.W. HardiesBouteloua curtipendula, B. eriopoda, B. gracilis, Hilaria belangeri, H. jamesii, H.mutica, H. rigida, Muhlenbergia porteri, Oryzopsis coerulescens, O. hymenoides, O. miliacea, Setaria macrostachya1936 (continued)Increased seed and forage production, longevity, and drought resistance.
California:  DavisL. G. GoarSorghum vulgare var. sudanense5 yearsIncreased hay and pasture productionMuch
Colorado:  Colorado Springs*E.W. HardiesAgropyron smithii1936 (continued)Increased seed and forage production, longevity, and drought resistanceMany promising variants found.
     Fort CollinsAlvin KezerBromus inermis1910-14Increased yield of forage
D.W. Robertson and Otto ColemanSorghum vulgare var. sudanense1934 (continued)(a) Yield and uniformity of seed; (b) reduced hydrochloric acid content(a) Much
Florida:  Gainesville*G. E. Ritchey and W. E. StokesAxonopus compressus10 years(a) Increased pasturage value: (b) reduced stolon development(a) Much; (b) little
Axonopus furcatusIncreased pasturage valueMuch.
Cynodon spp.-----------Medium to much
Digitaria spp.1933 (continued)Increased seed production and pasturage valueMedium
Eremochloa ophiuroides1931 (continued)Increased seed production, pasturage, and lawn valueMuch
Melinis minutiflora1933 (continued)(a) Increased pasturage value, (b) early seed production; (c) winter hardiness(a) Much (b) and (c) little
G.E. Ritchey and F. H. HullPaspalum notatumIncreased pasturage value and disease resistance-Much
G. E. Ritchey and W. E. StokesPennisetum purpureum1934 (continued)Increased pasturage and silage value and resistance to leaf spot
Georgia:  Tifton* (Coastal Plain Experiment Station)J. L. Stephens and G. W. BurtonCynodon dactylon1929 (continued)Increased hay and pasture production and winter hardinessMedium
Cynodon spp.1936 (continued)Increased seed production, palatability, and winter hardiness
Digitaria spp.----------Increased viable seed production, better turf, and winter hardiness
Panicum antidotaleProduction of nonshattering seed heads
Panicum purpurascensWinter hardiness and earliness
Paspalum dilatatumIncreased production of viable seed, leafiness, and disease resistance
Paspalum notatum
Pennisetum purpureumIncreased forage value and resistance to helminthosporium eye spot
Sorghum vulgare var. sudanenseResistance to foliage diseases
Iowa:  AmesH. D Hughes and F. S. WilkinsPhalaris arundinacea1921-32Increased seed and forage, disease resistance, leafiness, and density of turfMuch
Illinois:  UrbanaO. T. BonnettAgrostis alba1934 (continued)Increased yield of forage, disease resistance, and winter hardiness
Poa pratensisIncreased yield of forage, resistance to leaf rust and mildew, and winter hardiness
Kansas:  Hays* (Fort Hays Branch of Kansas Agricultural Experiment Station)D. A. Savage, H. E. Runyon, and R. E. SolomonAgropyron pungens, A. semicostatum, A. smithiiIn general the objective for all grasses is to develop drought-resistant grasses suitable for reseeding and resodding on different soil types in the central and southern Great Plains and to improve their forage value.Many promising variants found
Andropogon furcatus, A. hallii, A. scoparius, Bouteloua gracilis, B. hirsutaSpecial attention given to increased seed production and viability
Buchloë dactyloidesSpecial attention given to increased seed production and viability, and rapidity of vegetative spread
Bromus inermisEspecially to develop a type that will endure high temperatures
Elymus virginicusEspecially to improve forage quality
Sorghastrum nutansSpecial attention given to increased seed production and viability
     Manhattan*A. E. AldousAndropogon furcatus, A. scoparius1928 (continued)Increased seed and forage values and drought resistance
Bromus inermis1930 (continued)
Kentucky:  LexingtonE.N. FergusArrhenatherum elatius1931 (continued)Comparing local strain with commercial
Dactylis glomerata10 yearsIncreased forage production
Festuca elatior1931 (continued)Comparing local strain with commercial
Poa pratens7 yearsIncreased forage production, disease resistance, and turf density
Maryland:  (National Agricultural Research Center)H.A. Vinall and M.A. HeinDactylis glomerata1932 (continued)Pasture and hay types, leafiness, and late maturingMedium
Lolium multiflorum1930 (continued)Late maturing and rust resistance
Lolium perenneRust resistance and summer forage productionLittle
Poa compressa1934 (continued)Leafiness and increased density of turfMedium
Poa pratensisSummer forage production
     College ParkJ. E. Metzger and G. F. EppleyFestuca rubra5 yearsIncreased seed production and fine turf value
Michigan:  Augusta* (W. K. Kellogg Demonstration Farm)A.B. DorranceCynodon dactylon1930-36Winter hardiness
Poa pratensis1934-36Summer forage production and leafiness
Mississippi:  State CollegeH. W. BennettCynodon, Digitaria, Lolium, and Paspalum spp.1936 (continued)Increased seed production and forage value
Missouri:  Columbia*E. M. BrownDactylis glomerata1935 (continued)Increased pasturage production and leafiness
Poa pratensis1932 (continued)Increased pasturage production, drought, and heat resistance; dense turfMedium
Montana:  BozemanL. P. ReitzFestuca rubra1930-35Increased seed and forage production
Lolium perenne
Sorghum vulgare var. sudanense
Various native grasses1936 (continued)
     Havre* (Northern Montana Branch Station)M.A. BellAgropyron cristatum1925Medium
Agropyron inerme1934
Agropyron smithii
     Moccasin* (Judith Basin Branch Station)N. F. Woodward, H. E. Tower, and J. E. NortonAgropyron cristatum1924-26, 1929-34, 1935 (continued)Medium
Nebraska:  LincolnL. C. Newell, A. L. Frolik, and KeimAgropyron cristatum, A. smithii, Andropogon furcatus, A. scoparius, Bouteloua gracilis, B. curtipendula, Bromus inermis, Buchloë dactyloides, Dactylis glomerata, Panicum virgatum, Phalaris arundinacea, Sorghastrum nutans1936 (continued)Increased seed and forage production, drought and disease resistance, palatability, and longevity
New Jersey:  New BrunswickH.B. SpragueAgrostis canina1929 (continued)Increased seed, resistance to Pythium and brown patch, and turf qualityMuch
Festuca rubra1931 (continued)Increased seed, resistance to Pythium and creeping habitMedium
New York:  IthacaD. B. Johnstone-Wallace and C. H. MyersDactylis glomerataImproved pasture typesMuch
North Dakota:  Dickinson* (substation)Leroy MoomawAgropyron cristatum1928-35Increased seed and forage productionMedium
     Mandan* (United States Northern Great Plains Field Station).ϖGeorge A. Rogler1936 (continued)In general the objectives for all grasses at Mandan are increased seed and forage production, viability of seed, forage palatability, drought and disease resistance, and seedling vigor
Agropyron smithiiRapid spreading of rhizomes, and early foliage emergence
Andropogon furcatus, A. hallii, A. scopariusEarly foliage emergence
Bouteloua curtipendulaEarly foliage emergence and cold resistance
Bouteloua gracilisEarly foliage emergence
Bromus inermis----------
Bromus marginatusCold resistance
Buchloë dactyloidesEarly foliage, dense turf, tall seed stalks, rapid spreading.
Elymus canadensis----------
Elymus junceusNonshattering of seed
Oryzopsis hymenoides----------
Panicum virgatumEarly foliage emergence
Phalaris arundinaceaNonshattering of seed
Oklahoma:  Woodward* (United States Southern Great Plains Field Station)D. A. Savage, H. E. Runyon, and R. E. Solomon.Agropyron repens var. pungens, A. smithii, Andropogon furcatus, A. hallii, A. saccharoides, A. scoparius, Bouteloua chondrosioides, B. curtipendula, B. eriopoda, B. hirsuta, Buchloë dactyloides, Calamovilfa longifolia, Elymus virginicus, Panicum virgatum, Redfieldia fleruosa, Sorghastrum nutans, Zoysia japonicaTo develop drought-resistant grasses suitable for reseeding and resodding on different soil types in the central and southern Great Plains and to improve their forage value.
      StillwaterW. B. GernertBromus inermisRecent yearsIncreased forage productionMuch
Buchloë dactyloides
Phalaris arundinacea
Sorghum vulgare var. sudanense
Oregon:  Corvallis*H.A. Schoth and H.H. RamptonAgrostis oregonensis1935 (continued)Improved turf and seed productionϮMedium
Agrostis palustrisDeeper root system and ability to withstand brackish overflow
Agrostis sp.1928 (continued)Improved forage, turf, and seed production
Alopecurus pratensis1934 (continued)Increased forage, uniform seed maturity, and less shatteringMuch
Arrhenatherum elatius1932 (continued)Increased foliage and less seed shattering
Brachypodium pinnatum1928 (continued)More tender foliageLittle
Bromus inermis1922 (continued)Reduced rhizome development and early growthMedium
Dactylis glomerata1928 (continued)Improved forage and turf-forming pasture types
Festuca elatior var. arundinacea1920 (continued)More tender foliage and less seed shattering
Lolium multiflorum1930 (continued)Longevity and rust resistance
Lolium perenneLongevity, rust resistance, and more seed first year
Phalaris arundinacea1920 (continued)Wider adaptation as to soil and increased seed production; especially less shatteringMuch
Phalaris tuberosa var. stenoptera1930 (continued)Longevity, less seed shattering, and winter hardiness
Pennsylvania:  State CollegeH. B. MusserAgrostis canina1929-35Fine turf
Agrostis palustrisMedium
Poa pratensis1932 (continued)Improvement in pasture value and fine-turf quality
Rhode Island:  KingstonT. E. Odland and H. F. A. NorthAgrostis alba1930-34Purifying linesMuch
Agrostis canina1931-35(a) Purifying lines, (b) resistance to dollar spot, seed production, fine turf
Agrostis palustris1930-34Resistance to brown patch, dollar spot, and snow mold; and fine turfMedium
Agrostis tenuis1930 (continued)(a) Resistance to brown patch, (b) fine turf, (c) purifying lines(c) Much
Texas:  San AntonioϖGerald O. MottAndropogon furcatus, A. hallii, A. saccharoides, A. scoparius, Bouteloua curtipendula, B. gracilis, B. hirsuta, Panicum virgatum, Sorghastrum mutans1934 (continued)Increased production and viability of seed, forage value, longevity, and drought resistance
Spur (Texas Substation no. 7)R. E. DicksonBuchloë dactyloidesFew yearsSelection and increased yields of forage and seedMuch
Utah:  Logan*Wesley Keller and Dean F. McAlisterAgropyron cristatum, A. pauciflorum, A. smithii, Bromus inermis, Elymus canadensis, E. condensatus, Festuca idahoensis, Oryzopsis hymenoides, Poa bulbosa, P. mevadensis, Sporobolus airoides, Stipa comata1936 (continued)All species are selected for increased forage production, drought resistance, palatability, and a greater capacity for survival and reproduction under moderately heavy grazing.
Virginia:  Arlington (Arlington Experiment Farm, U. S. Department of Agriculture)Staff of U.S. Golf Association, Green SectionAgrostis canina1920 (continued)Dense turf, uniform texture, and resistance to diseases, trampling, and close clippingMuch
Agrostis palustris
Festuca rubra1931 (continued)Dense turf, uniform texture, and resistance to diseases, rapid spread, and close clippingLittle
Poa pratensisDense turf, uniform texture, and resistance to disease, drought, and close clipping
Poa trivialisDense turf and resistance to diseases and tramplingMedium
BlacksburgT. K. Wolfe and N. A. PettingerDactylis glomerata1920-36Increased forage valueMuch
Washington:λ  PullmanA. L. Hafenrichter and V.B. HawkAgropyron cristatum, A. pauciflorum1935 (continued)Increased seed and forage productionLittle
Pullman*D. C. Smith and G. W. FischerAgropyron cristatum1936 (continued)Sustained seed yields, increased palatability, and resistance to smut
Agropyron inermeLeafiness and improved seeding habit
Agropyron paucifiorumResistance to drought and diseases
Arrhenatherum elatiusIncreased palatability and leafiness, improved seeding habits, and smut resistance
Bromus inermisDrought resistance and improved seed production
Bromus marginatusSmoothness of foliage and smut resistance
Dactylis glomerataDrought and cold resistance and improved seed production
Elymus canadensisObtaining awnless and finer-stemmed types
Festuca elatiorIncreased palatability and better seeding habits
Phalaris arundinaceaDrought resistance, winter hardiness, and seed production
Wisconsin:  Madison*O.S. Aamodt, F. W. Tinney, and H. L. AhlgrenBromus inermis1935 (continued)Increased forage production, resistance to leaf spot, and reduced rhizomesMedium to much
Dactylis glomerata1936 (continued)Increased forage production with longer vegetative period and drought resistance
Poa pratensisIncreased forage production, resistance to mildew, and drought resistance
Wyoming:  Cheyenne (Cheyenne Horticultural Field Station, U.S. Department of Agriculture)Agropyron cristatum
β
Agropyron pauciflorumEmphasis on longevity
Agropyron smithii
Agropyron spicatum
Bouteloua curtipendula
Bouteloua gracilis
Bromus inermisReduced rhizome development
Bromus marginatusReduced awn development
Buchloë dactyloides
Elymus condensatusEmphasis on palatability
Stipa comata
Hawaii:  HonoluluC. P. WilsieBromus catharticus1934 (continued)Increased forage and seed production and resistance to smut
Digitaria milanjiana, D. pentzii1935 (continued)Increased pasturage, development of uniform pasture type
Pennisetum purpureum1933 (continued)Increased forage, leafiness, and palatability
Sorghum vulgare var. sudanense1933-34Increased forage, leafiness, and resistance to smut
CANADA
Alberta:  Edmonton (University of Alberta)M. O. Malte and G. H. CutlerAgropyron pauciflorumSeveral yearsImproved hay typeMedium
Ontario:  Guelph (Ontario Agricultural College)O. McConkeyAgropyron cristatum7 yearsIncreased seed production, forage yield, and (a) leafiness(a) Much
Agrostis alba10 yearsIncreased seed production, disease resistance, pasturage, (a) leafiness, and (b) winter hardiness(a) and (b) Medium
Bromus inermis4 yearsIncreased seed production, disease resistance, pasturage, and (a) leafiness(a) Medium
Dactylis glomerata10 yearsPasture and pasture-hay type, winter hardiness, and leafinessMuch
Festuca elatior10 yearsIncreased seed production, disease resistance, forage production, (a) leafiness, and (b) winter hardiness(a) and (b) Much
Festuca rubra6 yearsIncreased seed production, disease resistance, and turf and pasture valueMedium
Lolium perenne10 yearsIncreased seed and forage, disease resistance, and winter hardinessMedium hardiness
Phalaris arundinacea6 yearsIncreased seed, disease resistance, pasture value, leafinessMedium
Poa compressa10 yearsSame, also winter hardinessMuch
P. pratensis10 yearsMedium
Ottawa (Central Experimental Farm)L. E. Kirk and R. McVicarAgropyron pauciflorum1913-29Increased forage production, uniformity, fineness and abundance of leavesMuch
Dactylis glomerata1912 (continued)Winter hardiness
Festuca elatior1918 (continued)(a) Increased forage (b) uniformity in type suitable for hay and pasture(a) Little, (b) medium
Poa pratensis1919 (continued)(a) Increased forage production, (b) mildew resistance, (c) upright habit of growth, and also spreading habit of growth(a) Unestimated, (b) much, (c) much
Quebec:  Quebec (Macdonald College)L.S. Klinck, L. A. Waitzinger, G. P. McRostie, A. MacTaggart, and J. N. BirdDactylis glomerata1911-33Increased hay and aftermath, winter hardiness, and longevityMedium
SaskatchewanL. E. Kirk and T. M. StevensonAgropyron cristatum1915 (continued)Increased hay and pasturageMuch
Saskatoon (Dominion Forage Crops Laboratory)L. E. KirkAgropyron pauciflorum1922-29Increased hayMedium
T.M. Stevenson and W. J. White1933 (continued)Longevity----------
J. Bracken?-1921Increased hay and pastureMedium
L. E. Kirk and T. M. Stevenson.1923 (continued)Increased hay and pasture, reduced rhizome development, leafiness, and fineness of stemMuch
ψ Except where otherwise noted, the work is conducted at the State Agricultural Experiment Station.
An asterisk (*) indicates cooperation between the U. S. Department of Agriculture and the State agricultural experiment station.
ϖ  Bureau of Plant Industry and Soil Conservation Service cooperating.
ϮIn addition to objectives stated, general consideration is given in all species at Corvallis to increasing the quantity and quality of forage and resistance to insects and diseases.
λThe objectives listed for Washington are the ones to be emphasized in each instance.  In general the objectives for all species are increased seed and forage yields, greater palatability, and resistance to drought, heat, and disease.
β  All species at Cheyenne are being selected for increased early growth, seed production, winter hardiness, palatability, longevity, and drought and disease resistance. Additional or special objectives are indicated.


TABLE 3.―Nature and characteristics of interspecific hybrids previous reported
Parents of cross and chromosome numbers (2n)By whom madeInstitutionDate of crossCharacteristics of progeny
Dactylis glomerata 28 X D. aschersoniana 14Müntzing (20)Swedish Seed Association, Seed Control Laboratory, Svalof, Sweden1931-35The F1 chromosome number was 21; the male sterile and female partially sterile; when backcrossed on the D. glomerata produced well-developed plants that were self-fertile, more vigorous than the D. glomerata, and had ± 35 chromosomes.
Festuca arundinacea 42 X F. gigantea 42Nilsson (22)Swedish Seed Association, Seed Control Laboratory, Undrom, Sweden1934Chromosome number of the F1 was 42, but F1 progeny plants differed very much, one having a chromosome number of 84.
Jenkin (14)*Welsh Plant Breeding Station, Aberystwyth, Wales1930F1 sterile, pollen not liberated; but in many cases the F1 plants can be used as female parents for backcrossing, some more readily than others.
F. pratensis 14 X F. arundinacea 42Nilsson-Leissner*Swedish Seed Association----------Cross reported successful, but no description of progeny was given.
Jenkin (13)*Welsh Plant Breeding Station, Aberystwyth, Wales1924, 1928F1 sterile, pollen not liberated; but in many cases the F1 plants can be used as female parents for backcrossing, some more readily than others.
F. pratensis 14 X F. gigantea 421930
F. pratensis 14 X F. rubra 421922, 1928, 1930, 193110 percent of pollinated flowers produced seeds, but none of these germinated.
F. rubra 42 X F. ovina 141930F1 sterile, pollination very incomplete; but in many cases the F1 plants can be used as female parents for backcrossing, some more readily than others.
Lolium perenne 14 X L. multiflorum 14Woodforde (39)Department of Agriculture, Tasmania, Australia----------The F2 segregated in a ratio of 3.4:1 for seedling fluorescence, a characteristic of L. multifiorum. Italian characters were dominant. No genetic linkage between fluorescence and awned glumes.
Jenkin*Welsh Plant Breeding Station, Aberystwyth, WalesVariousF1 fertile; provisional conclusion that better results by selecting within either L. perenne or L. multifiorum than from the hybrid progeny.
L. perenne 14 X L. remotumF1 sterile, pollen not liberated; but in many cases the F1 plants can be used as female parents for backcrossing, some more readily than others.
L. perenne 14 X L. rigidumJenkin (14)F1 fertile, but no description of progeny given.
L. perenne 14 X L. temulentum 14Jenkin*1922F1 sterile, pollen not liberated; but in many cases the F1 plants can be used as female parents for backcrossing, some more readily than others. F1 of reciprocal cross similar in all essential characters.
L. temulentum 14 X L. loliaceum (?)1935Cross reported successful, but characteristics of F1 unknown.
L. temulentum 14 X L. remotum (?)1935
Phalaris arundinacea 28 X P. tuberosa 28Jenkin (16)1930Chromosome number of F1, 28, of which 12 are bivalent and 2 univalent. The hybrids are very vigorous and easily distinguishable from the parent species.
Poa arachnifera ±80 X P. pratensis 56E. Marion Brown*U.S. Department of Agriculture and Missouri Agricultural Experiment Station, Columbia, MO1934-35About 10 percent of the F1 hybrids are fertile; progeny of these are productive, have more vigorous rhizomes, and show greater resistance to heat and drought than P. pratensis.
P. pratensis 56 X P. alpina 32-34Müntzing*Swedish Seed Association, Svalof, Sweden-----------F1 fertile, but no description of progeny given.
Sorghum vulgare 20 X S. halepense 40Karper and Chisholm (16)Texas Agricultural Experiment Station, College Station, Tex.----------Chromosome numbers of F1, 30; an examination of the pollen mother cells of F1 plant showed univalents, bivalents, trivalents, and quadrivalents, but none of higher association.
Sorghum vulgare var. sudanense 20 X S. halepense 40Karper (2)----------1933Small percentage of success; F1 partially sterile
*Reported in correspondence (Y. B.Q).


TABLE 4.—Intergeneric hybrids previously reported
Parents of cross and somatic chromosome numbersBy whom madeInstitutionDate made or reportedRemarks
Aegilops cylindrica 28 X Agropyron longatum 70W.J. Sando*U.S. Department of Agriculture, Bureau of Plant Industry, Washington, D.C.193542 flowers pollinated; 3 seeds obtained, all of which produced plants
Aegilops longissima 14 X Agropyron elongatum 7048 flowers pollinated; 18 seeds obtained, none of which grew.
Aegilops speltoides 14 X Agropyron elongatum 70106 flowers pollinated; 2 seeds obtained, none of which produced plants
Aegilops crassa 42 X Agropyron intermedium 42Verushkin*Central Station of Plant Breeding Genetics, Saratov, Union of Soviet Socialist Republics46 flowers pollinated; 29 seeds obtained, 63 percent pollinations successful
Aegilops speltoides 14 X Agropyron intermedium 4228 flowers pollinated; 8 seeds obtained, 28.5 percent pollinations successful
Aegilops triaristata 28 or 42 X Agropyron intermedium 426 flowers pollinated; 3 seeds obtained, 50 percent pollinations successful
Aegilops triuncialis 28 X Agropyron intermedium 4212 flowers pollinated; 2 seeds obtained, 16.6 percent pollinations successful
Aegilops turcomanica 42 X Agropyron intermedium 42193618 flowers pollinated; 10 seeds obtained, 55.5 percent pollinations successful
Aegilops variabilis 28 X Agropyron intermedium 42193522 flowers pollinated; 6 seeds obtained, 27.3 percent pollinations successful.
Festuca arundinacea 42. X Lolium perenne 14Jenkin (13)Welsh Plant Breeding Station, Aberystwyth, Wales1921, 1928-30429 flowers pollinated; 26.8 percent set seed, but none germinated.
F. pratensis 14 X L. perenne 141922,1928-311,513 flowers pollinated; 27 percent set seed; 4.9 percent germinated; 7 plants established F1 male sterile.
F. rubra 42 or 56 X L. perenne 141921,1922,1928181 flowers pollinated; 13 seeds obtained; 7.2 percent set seed, but none germinated.
Lolium perenne 14 X F. arundinacea 421921, 1928, 1929, 1931654 flowers pollinated; 32.9 percent set seeds 39.5 percent germinated; 75 plants established, F1 sterile.
L. perrene 14 X F. gigantea 281921Successful in obtaining seed, but F1 sterile
F. Nilsson*Swedish Seed Association, Svalof, Sweden----------Cross reported successful, but no description given.
L. perenne 14 X F. ovina 28Jenkin (13)*Welsh Plant Breeding Station, Aberystwyth, Wales1930150 flowers pollinated; 16.7 percent set seed; none of which germinated.
L. perenne 14 X F. pratensis 141922, 1928-312,046 flowers pollinated; 41.1 percent set seed, germination 0.7 percent; 1 plant established; 1 sterile
F. Nilsson*Swedish Seed Association, Svalof, Sweden----------Cross reported successful, but no description given.
L. perenne 14 X F. rubra 42Jenkin (13)Welsh Plant Breeding Station, Aberystwyth, Wales1921, 1924, 1928218 flowers pollinated; 45.4 percent set seed; germination 18.2 percent; 9 plants established; F1 sterile.
F. Nilsson and G. Nilsson-Leissner*Swedish Seed Association, Svalof, Sweden----------Cross reported successful, but no description given
Triticum dicoccoides 28 X Agropyron elongatum 70W.J. SandoU. S. Department of Agriculture, Bureau of Plant Industry, Washington, D. C.193596 flowers pollinated; 7 seeds obtained; 4 seeds planted, 2 percent of which produced plants.
T. spelta 42 X A. elongatum 7054 flowers pollinated; 9 seeds obtained; 7 seeds planted, 6 percent of which produced plants
T. aestivum 42 X A. elongatum 702,128 flowers pollinated; 398 seeds obtained; 140 seeds planted, 10.5 percent of which produced plants.
T. dicoccum 28 X A. glaucum 42L.E. Kirk and R. McVicar*Central Experimental Farm, Ottawa, CanadaCross successful; F1 hybrids male sterile; may be backcrossed on Triticum parent.
T. durum 28 X A. glaucum 42
T. aestivum 42 X A. glaucum 42
T. dicoccum 28 X A. elongatum 70
T. durum 28 X A. elongatum 70
T. aestivum 42 X A. elongatum 70Cross successful; F1 hybrids showed partial fertility.
T. durum 28 X A. elongatum 70T.M. Stevenson and W.J. White*Dominion Forage Crops Laboratory, Saskatoon, Saskatchewan, CanadaCross reported successful, but fertility of F1 not yet determined.
T. polonicum 28 X A. elongatum 70
T. aestivum 42 X A. elongatum 70
T. durum 28 X A. glaucum 42
T. polonicum 28 X A. glaucum 42
T. aestivum 42 X A. glaucum 42
T. dicoccum 28 X A. glaucum 42Armstrong (1)Central Experimental Farm, Ottawa, Canada1935-361,196 flowers pollinated; 1,414 seeds obtained; 34.6 percent successful.
T. dicoccum 28 X A. elongatum no. 8201,391 flowers pollinated; 538 seeds obtained; 38.7 percent successful.
T dicoccum 28 X A. elongatum no. 1083196 flowers pollinated; 3 seeds obtained; 1.5 percent successful.
T. durum 28 X A. glaucum 421,224 flowers pollinated; 394 seeds obtained; 32.2 percent successful
T. durum 28 X A. elongatum no. 820, 70345 flowers pollinated; 11 seeds obtained; 3.2 percent successful.
T. durum 28 X A. elongatum no. 1083, 70164 flowers pollinated; 12 seeds obtained; 7.3 percent successful.
T. aestivum 42 X A. glaucum 421,041 flowers pollinated; 122 seeds obtained; 11.7 percent successful.
T. aestivum 42 X A. elongatum no. 820, 70239 flowers pollinated; 25 seeds obtained; 10.5 percent successful.
T. aestivum (Kharkov) 42 X A. elongatum no. 1083, 70328 flowers pollinated; 45 seeds obtained; 13.7 percent successful.
T. durum 28 X A. elongatum 70Vakar (34)Siberian Institute for Scientific Research of Grain Management, Union of Soviet Socialist Republics, Omsk----------Success with in the F1 hybrid
T. aestivum 42 X A. elongatum 70Success with cross; 56 somatic chromosomes in the F1 hybrid
T. aestivum X A. glaucum 42Success with cross; 42 somatic chromosomes in the F1 hybrid
T. aestivum 42 X A. intermedium 42Verushkin (35)Central Station of Plant Breeding and Genetics, Saratov, Union of Soviet Socialist Republics19353,062 flowers pollinated; 1,248 seeds obtained; 40.7 percent successful
T. sphaerocuccum 42 X A. intermedium 4280 flowers pollinated; 24 seeds obtained; 30 percent successful
T. compactum 42 X A. intermedium 4280 flowers pollinated; 10 seeds obtained; 12.5 percent successful
T. dicoccoides 28 X A. intermedium 42180 flowers pollinated 52 seeds obtained; 28.8 percent successful
T. dicoccum 28 X A. intermedium 42128 flowers pollinated 39 seeds obtained; 30.5 percent successful.
T. durum 28 X A. intermedium 421,207 flowers pollinated; 564 seeds obtained; 46.7 percent successful
T. polonicum 28 X A. intermedium 4248 flowers pollinated; 21 seeds obtained; 43.7 percent successful
T. persicum 28 X A. intermedium 42256 flowers pollinated; 131 seeds obtained; 51.2 percent successful
T. monococcum 14 X A. intermedium 4286 flowers pollinated; 14 seeds obtained; 16.3 percent successful
T. aestivum 42 X A. elongatum 702,136 flowers pollinated; 937 seeds obtained; 43.8 percent successful
T. sphaerococcum 42 X A. elongatum 7059 flowers pollinated; 31 seeds obtained; 52.5 percent successful
T. compactum 42 X A. elongatum 7018 flowers pollinated; 3 seeds obtained; 16.6 percent successful
T. dicoccoides 28 X A. elongatum 7054 flowers pollinated; 22 seeds obtained; 40.7 percent successful
T. dicoccum 28 X A. elongatum 70328 flowers pollinated; 93 seeds obtained; 28.5 percent successful
T. durum 28 X A. elongatum 701,128 flowers pollinated; 469 seeds obtained; 41.5 percent successful
T. turgidum 28 X A. elongatum 7024 flowers pollinated; 10 seeds obtained; 41.5 percent successful
T. persicum 28 X A. elongatum 7070 flowers pollinated; 26 seeds obtained; 37.1 percent successful
T. monococcum 14 X A. elongatum 7024 flowers pollinated; 0 seeds obtained; 0.0 percent successful
*Reported in reply to the Yearbook questionnaire, 1936.


TABLE 5.―Chromosome numbers of various grasses
Genus and speciesψ Somatic chromosome number (2n)β Referenceγ
Aeluropus littoralis var. dasyphylla Trautv.† 20 (5)
A. littoralis (Gouan) Parl. † 60 (5)
Agropyron acutum (DC.) Roem. and Schult35(46)
A. aegilopoides Drobov14(4)
A. caninum (L.) Beauv28 a(42)
A. ciliare (Trin.) Franch28(39)
A. cristatum (L.) Gaertn28 c(41)
A. cristatum (Fairway strain)14*π
A. dagnae Grossh14 a(42)
A. dasystachyum (Hook.) Scribn28(42)
A. desertorum (Fisch.) Schult.†28(42)
A. elongatum (Host) Beauv70(42)
A. glaucum (DC.) Roem. and Schult42(42)
A. griffithsii Scribn. and Smith28(42)
A. intermedium (Host) Beauv. (See. A. obtusiusculum)
A. japonicum Honda.= A. japonense Honda28(39)
A. junceum (L.) Beauv28 a(4)
A. mutabile Drobov28(4)
A. obstusiusculum Lange = A. intermedium42(42)
A. orientale (L.) Roem and Schult28(3)
A. pauciflorum (Schwein.) Hitche28 a(42)
A. prostratum (Pall.) Beauv14(4)
A. pungens (Pers.) Roem. and Schult42* a(42)
A. repens (L.) Beauv42 b(42)
28(4)
A. richardsoni Schrad. = A. susecundum28(41)
A. semicostatum (Stend.) Nees42(39)
A. sibiricum (Willd) Beauv.†28 b(42)
A. smithii Rydb56 a(3)
A. smithii var. molle (Scribn. and Smith) Jones28, 56(42)
A. spicatum (Pursh) Scribn. and Smith14(42)
A. subsecundum (Link) Hitche. (See A. richardsoni)
A. tunguscense Drobov28(4)
A. villosum (L.) Link14*(42)
Agrostis alba L.42 a(3)
A. nebulosa Bois. and Reut.14 a(4)
A. tenuis Sibth. (See A. vulgaris.)
A. verticillata Vill28(4)
A. vulgaris With. = A. tenuis28(3)
Apera spica-ventiL. (See Apera spica-venti.)
Alopecurus aequalis Sobol. (See A. fulvus)
A. agrestis L.=A. myosuroides14 a(3)
A. alpinus J. E. Smith. var. elatus Kom70(4)
A. fulvus J. E. Smith† = A. aequalis14(24)
A. geniculatus L28 a(3)
A. myosuroides Huds. (See A. agrestis.)
A. pratensis L28 d(3)
Ammophila breviligulata Fernald.28*(9)
Andropogon annulatus Forsk.†40*(23)
A. condylotrichus Hochst. (See A. piptatherus)
A. elliottii Chapm20(19)
A. furcatus Muhl70*(10)
A. gryllus L. = Rhaphs gryllus40(4)
A. halepensis (L.) Brot. (See also Sorghum halepense)40 f(3)
A. halepensis var20(24)
A. intermediusθ 70(10)
A. nardus L. = Cymbopogon nardus20(27)
A. piptatherus Hack.=A. condylotrichus40(4)
A. purpureo-sericeus Hochst.† = Sorghum purpureo-sericeum40(33)
A. saccharoides Swartz60(4)
A. scoparius Michx.40 a(10)
A. sorghum (L.) Brot.=Sorghum vulgare20 e(28)
A. sorghum Brot. var. sudanense Piper = Sorghum vulgare var. sudanense20 a(14)
A. versicolor = Sorghum versicolor10 a(22)
Anthephora hermaphrodita (L.) Kuntze18(3)
Anthoxanthum aristatum (Boiss) 10(3)
A. odoratum L20 b(3)
Apera spica-venti14(4)
Aplunda mutica L 40 a(3)
A. mutica L20(19)
Aristida adscensionis L22(5)
Arthraxon ciliaris Beauv. subsp. langsdorfii (Trin.) Hack40(3)
A. hispidus (Thunb.) Makino40(3)
Arundinaria fortunei (Van Houtte) Riviere†48(19)
A. glaucescens (Willd.) Beauv70-74(3)
A. hindsii Munro48(52)
A. pygmaea Kurz54(19)
Arundinella anomala Steud36(4)
Arundo donax L100+ a(4)
Asprella hystrix Willd.† = Hystrix patula28(3)
Atropis distans (L.) Griseb.=Puccinellia distans42(4)
A. distans (L.) Griseb28(47, 48)
14(4)
Avena algeriensis Trabut42(25)
A. barbata Brot.†28 d(25)
A. bruhnsiana Gruner14(12)
A. brevis Roth†14 b(40)
A. byzantina C. Koch†42 a(25)
A. clauda Dur14 a(40)
A. fatua L42 a(25)
A. flavescens L = Trisetum falvescens28(37)
A. ludoviciana Dur.†42(20)
A. nuda L42(20)
A. sativa L42 a(25)
A. sterilis L42 e(20)
A. strigosa Schreb.† subsp. abyssinica (Hocsht.) Hausskn.†28(12)
A. strigosa Schreb14 e(25)
A. wiestii Steud.†14 c(20)
Beckmannia erucaeformis (L.) Host.14(4)
Boissiera_bromoides Hochst. and Steud.†28(47, 48)
B. pumilio (Trin.) Stapf14(47, 48)
Bouteloua gracilis (H.B.K.) Lag.†42(»)
B. oligostachya (Nutt.) Torr. = Bouteloua gracilis40(47, 48)
Brachiaria erucaeformis (J.E. Smith) Griseb. (See Panicum erucaeforme)(47, 48)
B. mutica (Forsk.) Stapf36(19)
Brachypodium distachyon (L.) Beauv. (See Trachynia distachya)
B. pinnatum (L) Beauv.†28(24)
B. sylvaticum (Huds.) Beauv18(3)
Briza elatior S. Smith14-17(4)
B. maxima L14 a(3)
B. media L14 a(3)
B. minor L10 a(3)
Bromus abolinii Drobov14(4)
B. albidus Bieb28(4)
B. arduennesis Dum14(47, 48)
B. arvensis L14a(47, 48)
B. australis R. Br.†28(47, 48)
B. breviaristatus Buckl56(47, 48)
B. brizaeformis Fisch. and Mey14(3)
B. cappadocicus Boiss. and Bal42(47, 48)
B. carinatus Hook and Arn56 a(47, 48)
B. carinatus var. hookerianus (Thurb.) Shear14(47, 48)
B. catharticus Vahl. (See B. uniloides)
B. ciliatus L56(4)
B. ciliatus L14(47, 48)
B. erectus Huds.14(47, 48)
B. erectus Huds. subsp. eu-erectus56* a(24)
B. inermis Leyss56(3)
B. inermis Leyss42 a(47, 48)
B. intermedius Guss14(3)
B. japonicus Thunb14 a(3)
B. kalmii A. Gray14(47, 48)
B. macrostachys Desf28(3)
14(47, 48)
B. madritensis L28(4)
42(47, 48)
B. marginatus Nees56 a(4)
B. mollis L28 a(3)
B. pacificus Shear42(47, 48)
B. polyanthus Scribn42(47, 48)
B. pumpellianus Scribn42(47, 48)
B. purpurascens Del. = B. rubens28 a(47, 48)
B. ramosus Huds14(47, 48)
B. rigidus Roth. (See B. villosus)
B. rigidus var. gussonii (See. B. villosus var. gussonii)
B. rubens L. (See B. purpurascens)
B. secalinus L28 a(3)
B. sitchensis Trin.†42(47, 48)
B. squarrosus L14(47, 48)
B. sterilis L14(47, 48)
B. tectorum L14 a(3)
B. unioloides H. B. K. = B. catharticus28 a(47, 48)
B. variegatus Bieb42(47, 48)
B. villosus Forsk.† = B. rigidus42 a(3)
B. villosus var. gussonii Aschers. and Graebn.† = B. rigidus var. gussonii28(47, 48)
B. virens Buckl. = B. carinatus14(47, 48)
Buchloë dactyloides (Nutt.) Engelm.60(4)
Calamagrostis arundinacea (L.) Roth28(4)
C. epigeios (L.) Rothθ 70(4)
C. neglecta (Ehrh.) Gaertn.†θ 70(4)
Catabrosa auqatica (L.) Beauv21 ? a(47, 48)
Cenchrus barbatus Schum. (See C. catharticus)
C. brownii Roem. and Schult. (See C. inflexus)(47, 48)
C. catharticus Del.† = C. barbatus34(3)
C. echinatus L34(3)
C. inflexus R. Br. = C. brownii34(3)
C. myosuroides H.B.K.θ 70(3)
C. tribuloides L34 a(3)
Centhotheca latifolia (Osbeck) Trin24(4)
Chaeturus fasciculatus Link14(3)
Chloris acuminata Trin. = C. distichophylla40(3)
C. barbata (L.) Swartz=C. inflata20(3)
C. cucullata Bisch40(3)
C. distichophylla Lag. (See C. acuminata.)
C. gayana Kunth20 a(3)
C. inflata Link. (See C. barbala.)
C. submutica H. B. K.80(4)
C. truncata R. Br.40(3)
Cinna arundinacea L.40(3)
Cleistogenes serotina (L.) Keng. (See Diplachne serotina.)
Coix lacryma-jobi L20 a(4)
Cornucopiae cucullatum L.14(3)
Cortaderia argentea (Nees) Stapf. = C. selloana40(3)
C. selloana (Schult.) Aschers. and Graebn. (See C. argentea and Gynerium argenteum)
Corynephorus canescens (L.) Beauv14(4)
Cymbopogon nardus (L.) Rendle. (See Andropogon nardus)
Cynodon dactylon (L.) Pers.36(3)
C. dactylon30(19)
Cymosurus balansae Coss. and Dur14(3)
C. cristatus L14 a(3)
C. echinatus L14 a(3)
Dactylis aschersoniana Graebn.†14* b(24)
D. glomerata L28 d(11)
Dactyloctenium aegyptium (L.) Richt.†48(3)
Deschampsia caespitosa (L.) Beauv.28(3)
Desmazeria sicula (Jacq.) Dum14 b(3)
Digitaria exilis (Kipp.) Stapf.54(19)
D. sanguinalis (L.) Scop28*(10)
D. horizontalis Willd.†36(3)
Dinebra retroflexa (Vahl) Panz20(3)
Diplachne serotina (L.) Link† = Cleistogenes serotina40(4)
Echinaria capitata (L) Desf18(4)
Echinochloa crusgalli (L.) Beauv42*(10)
E. crusgalli (L.) Beauv. var. edulis Hitche. = E. crusgalli var. frumentacea56*(10)
E. crusgalli var. frumentacea (Roxb.) Wight. (See E. crusgalli var. edulis.)
E. frumentacea (Roxb.) Link = E. crusgalli var. frumentacea36(19)
Ehrharta panicea Sm.24*(4)
Eleusine coracana (L.) Gaertn36 b(3)
E. indica (L.) Gaertn.18(4)
E. tristachya (Lam.)18(3)
Elymus canadensis L42(10)
E. caput-medusae L. (See Hordeum caput-medusae.)
E. curvatus Piper = E. virginicus var. submuticus28(4)
E. dahuricus Turcz42(3)
E. giganteus Vahl28(4)
E. sibiricus L.28 a(3)
E. virginicus var. submuticus Hook. (See E. curvatus.)
Eragrostis abyssinica (Jacq.) Link.†40(3)
E. albida Hitche40(18)
E. aspera (Jacq.) Nels_20(4)
E. cambessediana (Kunth) Steud20(18)
E. capensis (Thunb.) Trin40(3)
E. cilianensis (All) Link. (See E. megastachya.)
E. japonica (Thunb.) Trin. [Trin.]20(3)
E. megastachya (Koel.) Link. = E. cilianensis20(3)
Eragrostis mexicana60(3)
E. pallescens Hitche80(18)
E. spectabilis (Pursh) Steud.†42(»)
E. tef (Zucc.) Trotter = E. abyssinica40(3)
Erianthus arundinaceus (Tetz.) Jeswiet †40, 60(8)
E. japonicus (Thunb.) Beauv. = Miscanthus japonicus60(7)
E. ravennae (L.) Beauv60(7)
Eriochloa villosa (Thunb.) Kunth54(3)
Euchlaena mexicana Shrad20 b(28)
E. perennis Hitche.40 c(44)
Eulalia japonica (Thunb.) Trin. = Miscanthus japonicus36(47, 48)
Festuca amethystina L28(47, 48)
F. arenaria Lam.42(37)
F. arundinacea Schreb. = F. elatior var. arundinacea42 c(44)
F. bromoides L. = F. dertonensis14(47, 48)
F. danthonii Aschers. and Graebn28(4)
F. danthonii Aschers. and Graebn. var. imberbis (Vis.) Aschers. and Graebn42(3)
F. dertonensis (All.) Aschers. and Graebn14(44)
F. duriuscula L. = F. ovina var. duriuscula42* b(9)
F. elatior L14g(37)
F. elatior var. arundinacea (Schreb.) Wimm. (See F. arundinacea.)
F. elatior L. subsp. arundinacea var. cirtensis St. Yves = F. elatior var. arundinacea70(30)
F. elatior L. subsp. arundinacea Hack. var. genuina Hack.= F. elatior var. arundinacea42 b(31)
F. elatior L. subsp. arundinacea Hack. var. uechtritziana (Wiesbaur) Hack. F. elatior var. arundinacea28(47, 48)
F. elatior L. subsp. pratensis Hack. var. apennina Hack. = F. elatior42 a(47, 48)
F. elatior var. pratensis (Huds.) A. Gray = F. elatior14* g(13)
F. elatior var. pratensis subvar. typica = F. elatior28(31)
F. geniculata Cav.†[(L.) Cav.]14(4)
F. gigantea (L.) Vill.42 b(30)
F. granatensis Boiss. = F. scariosa Lag14 a(30)
F. loliacea Huds.14(30)
F. mairei St. Yves.28 a(43)
F. maritima L.14(4)
F. montana Savi.14 a(30)
F. myuros L14(3)
F. myuros L42 a(47, 48)
F. ovina L56*(9)
F. ovina L. subsp. alpina (Suter) Wimm. and Grab14 b(31)
F. ovina L. subsp. eu-ovina Hack. var. duriuscula Hack. = F. ovina var duriuscula28((47, 48)
F. ovina L. subsp. eu-ovina Hack. var. duriuscula Koch subvar. geniuna Koch. = F. ovina var. duriuscula42 b(30)
F. ovina L. subsp. eu-ovina Hack. subvar. geniuna Hack.=F. ovina var. duriuscula70(47, 48)
F. ovina L. subsp. eu-ovina Hack. = F. ovina14 b(30)
F. ovina L. subsp. indigesta Hack. var. litardieri St. Yves=F. ovina var. indigesta70 a(30)
F. ovina L. subsp. sulcata Hack. var. dupalii St. Yves=F. ovina var. sulcata42 a(30)
F. ovina L. subsp. sulcata Hack. var. panciciana Hack. = F. ovina var. sulcata28(47, 48)
F. ovina var. duriuscula (L.) Koch. (See F. duriuscula.)
F. ovina var. tenuifolia (Sibth.) Sm28(31)
F. rubra L.42* b(9)
F. rubra L. subsp. eu-rubra var genuina Hack.= F. rubra56(30)
F. rubra L. subsp. heterophulla (Lam.) Hack. = F. rubra var. heterophylla (Lam.) Mutal42 a(30)
F. rubra L. subsp. nevadensis Hack. var. hackelii Lit. and Maire subvar. brevifolia Lit. and Maire = F. rubra var. nevadensis70 a(30)
F. rubra L. subsp. violacea (Gaud.) Hack.=F. rubra var. violacea14(47, 48)
F. scariosa Lag. (See F. gramatensis)
F. sibirica (Griseb.) Hack. (See Leucopoa sibirica.)
F. silvatica Vill42a(47, 48)
F. spadicea L14(44)
F. spadicea var. aurea (Lam. Richter. (See F. spadicea var. genuina subvar. aurea.)
F. spadicea aurea=F. spadicea var. aurea28(31)
F. tenuifolia Sibth.†=F. ovina var. tenuifolia14(37)
F. triflora Desf.14 a(30)
F. varia Haenke. (See F. varia subsp. pratensis Hack. subsp. eu-varia var. genuina.)
F. varia var. scoparia subvar. kerneri St. Yves28(31)
F. varia Haenke subsp. eskia (Ram.) St. Yves = F. varia var. eskia42(47, 48)
F. varia var. eskia Gren. and Godr. (See F. varia subsp. eskia.)
F. varia Haenke subsp. eu-varia Hack. var. genuina Hack.= F. varia Haenke28(47, 48)
Glyceria aquatica (L.) Wahl56(47, 48)
G. aquatica var. arundinacea Aschers28(47, 48)
G. distans Wahl. = Puccinellia distans28(47, 48)
G. fluitans (L.) R. Br28(47, 48)
G. nervata Trin. = G. striata28(47, 48)
G. plicata Fries28(47, 48)
G. spectabilis Mert. and Koch. = G. aquatica56(3)
G. striata (Lam.) Hitch. (See G. nervata)
Gynerium argenteum (Nees) Stapf. = Cortaderia selloana76(19)
Haynaldia villosa (L.) Schur14b(3)
Heleochloa schoenoides (L.) Host36(4)
Hierochlöe odorata (L.) Beauv.†42(3)
Holcos lanatus L14a(3)
H. mollis L14(47, 48)
Hordeum bulbosum L28(47, 48)
H. caespitosum Scribnθ 14(50)
H. caput-medusae (L.) Coss. and Dur. = Elymus caputmedusae14a(17)
H. jubatum L28c(2)
H. jubatum L. †θ 14(50)
H. murinum L. †28b(2)
H. murinum14a(47, 48)
H. nodosum L42(17)
H. nodosum L. †14(50)
H. pusillum Nutt.†14(50)
H. secalinum Schreb28b(47, 48)
H. silvaticum Huds28(47, 48)
Hystrix patula Moench. (See Asprella hystrix)
Imperata arundinacea Cyrillo20(7)
Ischaemum anthephoroides Miq68(28)
Koeleria cristata (L.) Pers70(4)
K. glauca (Schkuhr.) DC14(3)
K. panicea (Lam.) Domin14(4)
K. phleoides (Vill.) Pers26(3)
Lagurus ovatus L14(3)
Lamarckia aurea (L.) Moench14(3)
Leptochloa chinensis (Roth) Neesθ 40(3)
L. polystachya (R. Br.) Benth20(3)
Lepturus cylindricus (Willd.) Trin52(19)
L. filiformis (Roth) Trin14(3)
L. incurvatus Trin.= Pholiurus incurvusθ 36(3)
L. pannonicus (Host) Kunth. = Pholiurus pannonicus14(3)
Leucopoa sibirica Griseb. = Festuca sibirica28(3)
Lolium italicum A. Br. = L. multiflorum14a(3)
L. linicolum A. Br.° = L. remotum14(15)
L. multiflorum Lam14b(13)
L. perenne L14* e(13)
L. persicum Boiss. and Hohen14(13)
L. remotum Schrank. (See L. linicolum.)
L. temulentum L.14a(15)
Lycurus phleoides H.B.K.40(4)
Manisuris landulosa (Trin.) Kuntze. (See Rottboellia glandulosa.)
Melica altissima L.18b(3)
M. ciliata L. (See M. ciliata Guss. var. eligulata.)18(3)
M. ciliata Guss. var. eligulata= Melica ciliata(?)18(3)
M. micrantha Boiss. and Hohen18(3)
M. nutans L.18a(3)
Melinis minutiflora Beauv36a(3)
Mibora verna (Pers.) Beauv.†14(3)
Milium effusum L.28(3)
M. vernale Bieb.28(3)
Miscanthus japonicus (Thunb.) Anderss38(8)
M. saccharifer (Anderss.) Benth64(19)
M. sinensis Anderss.42* a(10)
Monerma cylindrica (Willd.) Coss. and Dur. = Lepturus cylindricus26(4)
Mublenbergia glomerata (Willd.) Trin.=Muhlenbergia racemosaθ 40(3)
M. mexicana (L.) Trin40(4)
M. pungens Thurb42(»)
M. racemosa (Michx.) B.S.P. (See Muhlenbergia glomerata.)
M. sylvatica Torr. (See Muhlenbergia umbrosa.)
M. umbrosa Scribn.= Muhlenbergia sylvatica40(4)
Nardus stricta L26(3)
Nassella trichotoma (Nees) Hack. (See Urachne trichotoma.)
Oplismenus burmanii (Retz.) Beauv.72(19)
O. compositus (L.) Beauv.72(4)
O. undulatifolius (Ard.) Roem. and Schult.†54(4)
Oryza cubensis Ekman.24(16)
O. latifolia Desv48(16)
Oryzopsis miliacea (L.) Benth. and Hook.†24(3)
O. virescens (Trin.) Beck.24(3)
Panicum capillare L18(3)
P. crusgalli L.= Echinochloa crusgalli54(3)
P. dichotomiflorum Michx54* a(10)
P. erucaeforme J. E. Smith = Brachiaria erucaeformis18(3)
P. crusgalli var. frumentaceum (Roxb.) Trimen.† =Echinochloa crusgalli var. frumentacea θ 48(45)
P. lindheimeri Nash18*a(10)
P. miliaceum L.†42(45)
P. miliaceum L36(4)
P. miliare Lam.†36(45)
P. plicatum Lam.= Setaria plicata54(3)
P. sanguinale L.= Digitaria sanguinalis36(3)
P. scribnerianum Nash18* a(10)
P. sphaerocarpon Ell18*(10)
P. subvillosum18*(10)
P. tsugetorum Nash18*(10)
Paspalum dilatatum Poir.†40* a(35)
P. muhlenbergii Nash=Paspalum pubescens20*(10)
P. pubescens Muhl. (See P. muhlenbergii.)
P. scrobiculatum L40(3)
P. stoloniferum Bosc.†20* a(35)
P. stoloniferum Bosc.†20-23(6)
P. virgatum L80(4)
Penicillaria spicata (L.) Willd =Pennisetum glaucum14(4)
Pennisetum_cenchroides (L.) Rich = Pennisetum ciliare36(4)
P. ciliare (L) Link. (See P. cenchroides.)
P. clandestinum Chiov.†36a(29)
P. glaucum (L.) R. Br.14*(23)
P. longistylum Hochst45(4)
P. macrourum Trin.54(4)
P. orientale L. Rich.36(3)
P. ruppelii Steud.†27(4)
P. setosum (Swartz) L. Rich54(3)
P. typhoideum L. Rich. = P. glaucum14(45)
P. villosum R. Br45(4)
Phaenosperma globosa Munro.24(4)
Phalaris arundinacea L.14* d(9)
P. arundinacea28a(37)
P. arundinacea L. var. picta L.28*(9)
P. canariensis L12 b(3)
28(38)
P. minor Retz28(3)
P. paradoxa L14(4)
P. tuberosa L.28(ϔ)
P. tuberosa var. stenoptera (Hack.) Hitche28(»)
Phleum asperum Jacq.†28b(3)
P. boehmeri (L.) Wibel14a(3)
P. michelii All14*(24)
P. paniculatum Huds. var. annuum (Bieb.) Griseb28(3)
P. phleoides (L.) Karst14(19)
P. pratense L42b(3)
Pholiurus incurpus (L.) Schinz and Thell. (See Lepturus incurvatus.)
P. pannonicus (Host) Trin. (See Lepturus pannonicus.)
Phragmites communis (L.) Trin54a(3)
P. communis (L.) Trin36a(51)
48(19)
θ 96(4)
P. communis (L.) Trin42*(51)
Phyllostachys edulis (Carriere) Lehaie †48(52)
P. flexusa A. and C. Riviere54a(52)
P. heterocycla Mitford †48(52)
P. “maliacum" error for P. marliacea Mitford?70-74(3)
P. nigra Munro.48(52)
P. reticulata Koch48(52)
Poa alpina L.32-34(3)
P. alpina L.22-38(36)
P. alpina L. var. badensis (Haenke) Mert. and Koch.42(47, 48)
P. annua L.20(24)
20(24)
P. bulbosa L42(47, 48)
P. caesia J. E. Smith42(47, 48)
P. compressa L.42a(4)
56(47, 48)
14(44)
P. glauca Vahl70(3)
P. nemoralis L.28(3)
42a(47, 48)
56(36)
P. palustris L42a(47, 48)
20(»)
P. palustris L. var. fertilis (Host) Aschers. and Graebn28(3)
P. palustris L70(38)
P. pratensis L56b(4)
42(47, 48)
28-85c(4)
49-85(36)
48-90(1)
P. pratensis var. angustifolia (L.) Gaud.†=P. pratensis L.28(4)
P. pratensis var. angustifolia (L.) Gaud.†=P. pratensis L.56(4)
P. pratensis var. angustifolia (L.) Gaud.† = P. pratensis L70(4)
P. sudetica Haenke14(3)
P. trivialis L.14 a(3)
P. violacea Bell28(47, 48)
Pollinia imberbis Nees40(3)
Polypogon littoralis (With.) J. E. Smith(4)
P. monspeliensis (L.) Desf28(3)
Polytoca macrophylla Benth40(4)
Psilurus aristatus (L.) Lange28(3)
Puccinellia distans (L.) Parl. (See Atropis distans and Glyceria distans)
Rhaphis gryllus (L.) Desv. (See Andropogon gryllus.)
Rottboellia glandulosa Trin.= Manisuris glandulosa54(4)
Schismus barbatus (L.) Chase (See S. calycinus.)
S. calycinus (Loefl.) Duval-Jouve =S. barbatus12(4)
Sclerochloa dura (L.) Beauv14(3)
Schleropoa rigida (L.) Griseb14a(3)
Sesleria argentea Savi28(4)
S. autumnalis (Scop.) F. Schultz28(3)
S. coerulea (L.) Ard28*(24)
S. tenuifolia Schrad42(3)
Setaria glauca (L.) Beauv. = S. lutescens36(3)
S. italica (L.) Beauv18b(3)
S. lutescens (Weigel) F. T. Hubb. (See Setaria glauca.)
S. plicata (Lam.) T. Cooke. (See (Panicum plicatum.)
S. verticillata (L.) Beauv.36(3)
S. viridis (L.) Beauv18(3)
Sinobambusa tootsik Makino48(52)
Sorghastrum nutans (L.) Nash40*(10)
Sorghum drummondii (Nees) Hack.=Sorghum vulgare var. drummondii20(33)
S. effusus (Hack.) Karper and Chisholm20(23)
S. halepense (L) Pers.40(24)
S. halepensis = var. miliformis (Schult.) Karper and Chisholm40(24)
S. hewisoni (Piper) Longley20(24)
S. purpureo-sericeum (Hochst.) Schweinf and Aschers. (See Andropogon purpureo-sericeus.)
S. vulgare var. drummondii (Nees) Hitche. (See S. drummondii.)
S. vulgare var. sudanense (Piper) Hitche20(24)
S. versicolor Anderss.10a(33)
S. verticillifiorum (Steud.) Stapf.20(23)
S. virgatum (Hack.) Stapf20(24)
S. vulgare Pers. (See Andropogon sorghum.)
Spartina aiternifiora Lois70(21)
S. cynosuroides (L.) Roth80-90(3)
S. michauxiana Hitche. = S. pectinata28*(9)
S. pectinata Link. See S. michauxiana)
S. schreberi F. Gmelθ 40(3)
S. stricta (Ait.) Roth56(21)
S. townsendii H. and J. Groves126(21)
Sphenopus divaricatus (Gouan) Reichb12(3)
Sporobolus berteroanus(Trin.) Hitche. and Chaset=S. poiretii36(4)
S. diandris (Retz ) Beauv36(3)
S. indicus (L.) R. Br18, 36(3)
S. poiretii (Roem. and Schult.) Hitche. (See S. berteroanus)
S. tenuissimus (Mart.) Kuntze40(19)
Stipa capillata L44(3)
S. lessingiana Trin. and Rupr.44(4)
S. papposa Nees42-44(3)
S. pulcherrima C. Koch44(4)
S. sibirica (L.) Lam24(3)
S. stenophylla Czern44(4)
S. ucrainica P. Smirn44(4)
Themeda arguens (L.) Hack20(3)
T. forskalii Hack60(4)
Trachynia distachya (L.) Link = Brachypodium distachyum30(4)
Tragus racemosus (L.) All.†40(3)
Trichloris mendocina (Phil.) Kurtz.40(4)
Tricholaena rosea Nees.36(8)
Triodia flava (L.) Smyth. (See T. flava.)
T. cuprea Jacq.=T. flava42(3)
Tripsacum dactyloides (L.) L.70(32)
T. dactyloides (L.) L36(19)
T. dactyloides (L.) L †36, 72(34)
T. lanceolatum Rupr±70(32)
T. laxum Nash±70(32)
T. pilosum Scribn. and Merr±70(32)
Trisetum flavescens (L.) Beav24 b(4)
T. sibiricum Rupr.14(4)
Uniola latifolia Michx48(3)
Urachne trichotoma (Nees) Trin. = Nassella trichotoma38(3)
Ventenata macra (Stev.) Boiss. and Bal.14(3)
Vulpina alopecurus Dum. = Festuca sp.14(3)
V. bromoides (L.) S.F. Gray † = Festuca bromoides = F. myuros or F. dertonensis14(47, 48)
V. myuros (L.) Gmel.† = Festuca myuros42(50)
V. myuros (L.) Gmel.14(3)
ψ Authorities for the botanical names used have been corrected to agree with the International Code and the U. S. Department of Agriculture style.  Those names for which no authority was given in the original are indicated by a dagger (†) and the recognized authority for the name has been inserted, but this does not mean that the grasses were correctly identified by the cytologist.
β Letters following chromosome numbers denote the number of times this number has been verified by other authors than the one indicated by the reference in the last column. a=1, b=2, c=3, d=4, e=5, f=6, g=7. An asterisk (*) indicates those reported as the “n" number, the number here given being double that reported.
γ Numbers in parentheses refer to References for Chromosome Numbers, p. 1099. Where a number has been verified by several workers, only: the first report of that number is cited.
π W. N. Myers, personal correspondence.
θ About.
» L. M. Humphrey; personal correspondence.
ϔ B. L. Sethi, personal correspondence.


REFERENCES FOR CHROMOSOME NUMBERS

(1) Åkerberg, E. 1936. STUDIEN UBER DIE SAMENBILDUNG BEI POA PRATENSIS L. Bot. Notiser 1936: 213-280, illus. [English summary, pp. 268-269.
(2) Aase, H. C., and Powers, L. 1926. CHROMOSOME NUMBERS IN CROP PLANTs. Amer. Jour. Bot. 13:367-372, illus.
(3) Avdulov, N. P. 1928. KARYO-SYSTEMATISCHE UNTERSUCHUNG DER FAMILIE GRAMINEEN. Allruss. Bot. Kong. Ber. 1928: 65-66.
(4) ―  1931. KARYO-SYSTEMATISCHE UNTERSUCHUNG DER FAMILIE GRAMINEEN. 428 pp., illus. Leningrad. Trudy Prikl. Bot., Genet. i Selek. Prilozh. (Bull. Appl. Bot., Genetics, and Plant-Breeding Suppl. 44.)
(5) ―  1933. ON THE ADDITIONAL CHROMOSOMES IN MAIZE. Trudy Prikl. Bot., Genet. i Selek. (Bull. Appl. Bot., Genetics, and Plant-Breeding) (2) 2: [101]-130. [Russian, pp. [101]-120; English, pp. 120-130.]
(6) ―  and Titova, N. 1933. ADDITIONAL CHROMOSOMES IN PASPALUM STOLONIFERUM BOSCO. Trudy Prikl. Bot., Genet. i Selek. (Bull. Appl. Bot., Genetics, and Plant-Breeding.) (2) 2: [165]-172. [In Russian. English summary, pp. 171-172.]
(7) Bremer, G. 1924. DE CYTOLOGIE VAN HET SUIKERRIET. IIl. DE CHROMOSOMEN BIJ PRIMITIEVE VORMEN VAN HET GESLACHT SACCHARUM. Archief voorde Suikerindust. Nederland.-Indië. (Meded. Proefsta. Java-Suikerindus.) 32: 477-508, illus.
(8) BREMER, G. 1934. DE CYTOLOGIE VAN HET SUIKERRIET. 7DE BIJDRAGE. EEN cytoLOGISCH ONDERZOEK VAN EEN VIJFTIGTAL IN 1920-1930 OF Java GEIMPORTEERDE RIETSOORTEN. Arch. Suikerindust, Nederland Indië deel 2, Meded. Jaarg. 1934 (5): [141]-166, illus.
(9) CHurch, G. L. 1929. MEIOTIC PHENOMENA IN CERTAIN GRAMINEAE. I FESTUCEAE, AVENEAE, AGROSTIDEAE, CHLORIDEAE, AND PHALARIDEAE. Bot. Gaz. 87: 608-629, illus.
(10) ―  1929. MEIOTIC PHENOMENA IN CERTAIN GRAMINEAE. II. PANICEAE AND ANDROPOGONEAE. Bot. Gaz. 88: 63-84, illus.
(11) Davies, J. G. 1927. THE CHROMOSOME NUMBER IN DACTYLIS GLOMERATA (COCKSFOOT), Nature [London] 119: 236-237.
(12) Emme, E. K. 1930. KARYOSYSTEMATICAL INVESTIGATION OF THE SECTION EU-AVENA GriseB. Trudy Vsesoiuz. S’ezd Gen., Selek., Semenov, i Plemenn, Zhivotnov. U.S.S.R. Cong. Genet. Plant and Anim. Breed. Proc. (1929) 2: 585-586. [In Russian. Title also in English.]
(13) Evans, G. 1926. CHROMOSOME COMPLEMENTS IN GRASSEs. Nature [London] 118: 841,
(14) Favorov, A. M. [Faworow, A. M.] 1929. HYLOGENETISCHE UNTERSUCHUNG DER SORGHUMARTHEN. Nauk. Pratsi Ukrain. Genetiko-Selek. Inst. (Wiss. Arb. Ukrain. Inst. Vererbungsforsch u. Pflanzen-zücht.) 1: 65-63. [In Ukrainian, German Summary, pp. 72-73.]
(15) Favorski, N. [Faworskr, N.] 1927. VERGLEICHENDE KARYOLOGISCHE UNTERSUCHUNG EINIGER ARTEN VON LoL1uM. Planta, Arch. Wiss. Bot. 3: [282]-291, illus.
(16) Gotoh, K., and Okura, E. 1933. A PRELIMINARY NOTE ON CYTOLOGICAL STUDIES OF ORYZA. Nettai Nôgaku Kwaishi (Jour. Soc. Trop. Agr.) 5: 363-364, illus.
(17) Griffee, F. 1927. CHROMOSOME NUMBER IN SPECIES OF HORDEUM. Minn. Univ. Studies Biol. Sci. 6: 319-331, illus.
(18) Hagerup, O. 1932. UBER POLYPLOIDIE IN BEZIEHUNG ZU KLIMA, KOLOGIE UND PHYLOGENIE CHROMOSOMENZAHLEN AUS TIMBUKTU. Hereditas 16:[19]-40, illus.
(19) HunTER, A. W. S. 1934. A KARYOSYSTEMATIC INVESTIGATION IN THE GRAMINEAE. Canad. Jour. Research 11: 213-241, illus.
(20) Huskins, C. L. 1926. GENETICAL AND CYTOLOGICAL STUDIES OF THE ORIGIN OF FALSE WILD oaTs. Seci. Agr. 6: 303-313, illus.
(21)―1930. TH‘Elll ORIGIN OF SPARTINA TOWNSENDIL Genetica 12: [531]-538, illus.
(22) Karper, R. E. 1930. INHERITANCE IN GRAIN SORGHUMS. Texas Agr. Expt. Sta. Ann. Rept., 43: 48-51.
(23) ―  and ChishoLm, A. T. 1936. CHROMOSOME NUMBERS IN SORGHUM. Amer. Jour. Bot. 23: 369—374, illus.
(24) Kattermann, G. 1930. CHROMOSOMENUNTERSUCHUNGEN BEI GRAMINEEN. Planta. Arch. Wiss. Bot. 12: [19]-37, illus.
(25) Kihara, H. 1919. UEBER CYTOLOGISCHE STUDIEN BEI EINIGEN GETREIDE ARTEN MITTEILUNGEN II. CHROMOSOMENZAHLEN UND VERWANDTSCHAFTS-VERHALTNISSE UNTER AVENA-ARTEN. Bot. Mag. [Tokyo] 33:94-97, illus.
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NOTES & FOOTNOTES
The purpose of this article is to bring together as far as possible the available information as to the breeding in progress and that contemplated with all grasses of agricultural importance with the exception of timothy, sugarcane, and the cereal grasses such as corn, sorghum, rice, wheat, rye, oats, and barley. As considerable breeding work has been done with timothy, it is discussed in a separate article.
2.  Died Feb. 22, 1937.
3.  The authorities for the botanical names used in this article are given in table 5 of the appendix.
4.  Italic numbers in parentheses refer to Literature Cited, p. 1074.
5.  Acreage of pasture on farms is given for 1934. The National Resources Board also furnished data on grazing land (33, pt. 2, table 2, p. 109). The 1930 acreage figures for grazing land not in farms were adjusted by O. E. Baker for 1934.
6.  U.S. DEPT. OF AGR., BUREAU OF BIOLOGICAL SURVEY. WILD LIFE REVIEW. 1936. [Mimeographed.]
7.  The data are taken from unpublished reports or summaries of results from the various stations indicated: Guthrie, Okla., Soil Conservation Service Circ. L-1121 (1936); Temple, Tex., Soil Conservation Service Circ. L-1134 (1936); Hays, Kans., Soil Conservation Service Circ. L-1134 (1936); La Crosse, Wis., Soil Conservation Service Circ. L-1122 (1936).
8.  These estimates of expenditures were supplied by John Monteith, Jr., collaborator, Division of Forage Crops and Diseases, Bureau of Plant Industry, U.S. Department of Agriculture.
9.  This abbreviation will be used in the following pages to indicate that the information was received in reply to the Yearbook questionnaire, sent out in the cooperative survey of plant and animal improvement.
10.  The following section is intended primarily for students and others professionally interested in genetics or breeding.
11. Personal correspondence, 1936.
12.  Synonym for T. aestivum.
13.  Personal correspondence, 1936.