Source: Magness et al. 1971
The yellow-flowered sweet clovers grown in the United States are all biennial. As compared to white-flowered M. alba, the yellow-flowered is finer stemmed, matures earlier in summer, is more tolerant to drought and competition with companion crops, and gives a better quality but lower yield of hay. Because of better drought tolerance the yellow-flowered is better adapted to the Great Plains. The first season, a central much-branched stem is produced with a deep tap root which becomes fleshy in the fall. The second year, crown buds start growth early with vigorous, rather coarse stems. Leaves are trifoliate, the leaflets being long-oval in shape. For hay, the second season crop should be cut early. Several varieties are in the trade. Madrid makes strong seedling growth, is leafy and later maturing the second year, well adapted to the Great Plains. Gold Top is vigorous and late maturing, giving longer pasture. Erector, developed in Canada, makes good growth in the Northeastern Great Plains.