FARM CROPS. 187 



to the grass family, which also contains our principal 

 cereals. Next in importance to the grasses are the 

 legumes, plants like clovers, alfalfa, cowpeas, peanuts, 

 soy beans and velvet beans, all of which are able to 

 use the nitrogen of the air, which most plants cannot 

 obtain. Outside of these two plant families there are 

 few important forage crops, perhaps the most valua- 

 ble being rape and kale of the cabbage family and 

 mangels of the beet family. 



Characteristics of Forage Plants. In both grasses 

 and legumes, as well as other forage crops, there are 

 parennials, living for several or many years, as well as 

 annuals, which live for only one year or season. Some 

 annuals are adapted for growing only in the summer, 

 others for growing in the winter. Perennial forage 

 crops are especially used in permanent meadows and 

 pastures. The most valuable for this purpose are not 

 only palatable and nutritious but able to occupy the 

 ground against weeds, and in the case of pasture 

 grasses to withstand continual trampling and close 

 cropping. Some indeed occupy the ground so tena- 

 ciously that they become more or less troublesome as 

 weeds, such as Johnson grass and Bermuda grass. A 

 few annual forage plants reseed themselves readily, 

 such as crab grass, lespedeza and bur clover. 



Perennial Grasses. The more important peren- 

 nial forage grasses are timothy, Kentucky blue grass, 

 Bermuda, orchard grass, redtop, tall meadow oat 

 grass, Johnson grass, brome grass, meadow fescue, 

 carpet grass and Para grass. 



Annual Grasses. Among the annual grasses used 

 for hay, besides such small grains as oats, wheat, bar- 

 ley and rye, are the millets, rescue grass, crab grass 

 and cheat. Here also might be included the coarser 

 grasses, such as the sorghums, pearl millet and teo- 

 sinte. 



Perennial Legumes. Practically the only perennial 

 legumes grown on American farms are alfalfa and the 

 clovers, red, white and alsike. 



