436 BOTANY OF CROP PLANTS 



Geographical, and Uses. — Crimson clover is a native of 

 Europe. It has become naturalized in the eastern portions 

 of the United States, where it occurs quite commonly in 

 waste places. The plant is grown in this country mainly 

 as a crop for hay, forage, or silage. It also has some value 

 as a soiling crop and as a cover crop. The hay sometimes 

 proves dangerous to horses, due to the tendency of the hairy 

 calyces to form indigestible masses in the stomach of the 

 animal, especially if the plants are too ripe when cut. These 

 hair balls seldom form in the stomachs of cattle and sheep. 



Enviromnental Relations. — Crimson clover is less resistant 

 to low temperatures than any of the other common clovers. 

 It is grown with success in orchards, because of its shade 

 tolerance. Although it prefers sandy soil, it will do well in 

 soils of heavier type. 



THIFOtlUM PRATENSE (Common Red or Purple Clover) 



Habit, Stems and Roots. — This is a perennial plant, more 

 or less hairy, branching, decumbent or erect, 6 to 24 inches 

 tall, rising from the crown. The life period is a varietal 

 character. The average is about three years. It develops 

 from a strong tap root which possesses an extensive system 

 of laterals. The tap root reaches a depth of 3 or 6 feet. 

 It draws moisture and mineral nutrients from the lower soil 

 layers. In general there is about i pound of root to 2 pounds 

 of plant above ground. This means that the clover crop 

 leaves considerable organic matter in the soil. 



Leaves. — The leaves are of the clover type, with hairy- 

 margined leaflets and large conspicuously purple-veined 

 stipules. The leaflets often bear a pale spot in the center. 



Inflorescence and Flowers. — The terminal inflorescences 

 are ovate (Fig. 184). Each inflorescence has from 35 to 150 

 purple-rose flowers. The second crop usually has more flowers 



