Crimson clover (Trifolium incarnatum) is the most important winter annual legume of the central section of the Eastern States. This crop can be grown over a much larger area by using seed of adapted varieties for each section, by using better cultural methods, and by fertilizing the soil (fig. 1). Besides being an excellent pasture plant and furnishing plenty of hay, it protects the soil during fall, winter, and spring, prevents soil washing, and provides green manure for soil improvement. This legume has the distinct advantage of producing large quantities of seed that can be easily harvested and sown without the use of expensive machinery. Crimson clover is a native of Europe and is widely grown in France, Hungary, and other central and southern European countries. Seed was introduced into this country as early as 1819, but it was not until 1880 that the plant became important. The acreage has been steadily increasing. During the 5-year period 1940-45 the annual purchase of seed through markets in the United States has ranged from 6 to 18 million pounds. In 1935 about 2 million pounds were used. In addition, large quantities of home-grown seed are handled from farm to farm.

The common name of this clover is derived from the bright crimson color of the blossoms. Other such common names as German clover and scarlet clover are frequently used. In general the leaves and stems resemble those of red clover, but are distinguished by the rounded tips of the leaves and more hair on both leaves and stems. When crimson clover is planted in fall the leaves develop from the crown and form a rosette, which enlarges whenever weather conditions are favorable. In spring, flower stems develop rapidly and end their growth with long pointed flower heads. Seed forms and the plant dies with the coming of hot summer weather. The seed is yellow and is about twice as large as red clover seed and more rounded.