The recent rapid increase in the culture of sweet clover has aroused interest in the possibility of developing new varieties better suited to the different uses to which the plant is put. Interest has centered principally in the production of better hay varieties, since the common sweet clovers, especially the white-flowered species, are too coarse and heavy to make good hay from the second year’s growth. Several good hay varieties have already been developed, notably the early-flowering Grundy County, Crystal Dwarf, and Early Dwarf varieties of white sweet clover and the Albotrea and Switzer varieties of yellow sweet clover.

FIG. 220.—Some sweet clovers furnish pasturage much later in the season than others. On November 24, 1925, the variety in the center was still green, while the varieties on either side had been killed to the ground four weeks earlier

A very interesting recent development in this direction has been the finding, at two of the western Canadian experiment stations, of a type of sweet clover bearing many more and finer stems than the common sorts, and in fact so closely resembling alfalfa in appearance that it is easily mistaken for that plant. This is a very import- ant discovery, and bids fair to add a distinct new type of forage plant to our list.

FIG. 221.—Sweet clovers differ greatly in leafiness and coarseness of stems. These two plants were taken from the same field of yellow sweet clover

The need for sweet clovers which are more winter-hardy has been met with Arctic, or Hansen’s Siberian, a white-flowered variety from western Canada, and Albotrea, also from Canada. A sweet clover much better suited than common sweet clovers to the cold, dry climate of the northern Great Plains appears to have been found in an unknown yellow-flowered variety developed at the Redfield, S. Dak., field station of the United States Department of Agriculture.

Several persons are endeavoring to find a sweet clover that will grow on acid soils, the need of lime in the soil being a serious hindrance to the culture of the crop in many localities. Other persons are trying to develop a sweet clover especially suited to withstanding the extreme drought and hot winds of the southern Great Plains. It is too early to say whether these efforts will succeed.

A type of sweet clover that would be exceedingly useful is one that would remain green late in the fall, start growth early the next spring, and remain green and in good feeding condition well into the following summer. Such a sweet clover would be immensely valuable for pasture purposes. A number of experimenters, both on farms and at experiment stations, have approached this type with selections of common white sweet clover. Perhaps even better results will come from tests now being made with species and varieties brought in from Europe and eastern Asia, one such species this year having remained green six weeks later than any sweet clover heretofore grown.

All sweet clovers are exceedingly variable in their habits of growth, and many distinct types and forms may be found in nearly any sweet-clover field (fig. 221). Although it would not be desirable to flood the country with new sweet clovers, there is a legitimate opportunity to develop useful types of proved superiority.