GRASS ROOTS 309 



year after year without deteriorating, but often improving, over- 

 comes its rather low yield. 



Origin of Forage Grasses. Out of the 1400 native grasses in 

 America only one has found a place in culture. This is the slender 

 wheat grass (Agropyron tenerum) of the western plains. It is 

 adapted to a large area and does well under irrigation. 



All the rest of our cultivated grasses have an Old World origin, 

 mostly from Europe. These grasses are found as wild grasses in 

 their native country, but some have practically run wild over the 

 United States since their introduction, as blue-grass and redtop. 



The Improvement of Grasses. Little has been done in de- 

 veloping varieties of forage grasses, most of the cultivated forms 

 being identical with the wild forms. With wheats we probably have 

 1000 varieties, and 500 varieties of corn, but only one variety of 

 timothy or of blue-grass. Work is now being carried on at several 

 places in developing varieties of grass, and it is likely that in time we 

 shall have commercial varieties of timothy and other grasses, with 

 special adaptation to different soils and climates or suited to special 

 uses, as pasture or hay forms. 



CHARACTERISTICS OF GRASSES 



The botanists often group wild grasses according to adaptation, as 

 sand binders, marsh grasses, bunch grasses, etc. 



Cultivated grasses are sometimes grouped as lawn grasses, pas- 

 ture grasses, hay grasses, etc. To fully understand the uses of 

 grasses a little study of grass characters is essential. 



Grass Roots. Grasses have fibrous roots in contrast with the 

 legumes that have tap roots. Grasses, on the whole, are considered 

 rather shallow-rooted plants. Where sods have been examined, from 

 80 to 90 per cent of the roots are usually found in the upper six 

 inches. A few roots usually penetrate to a depth of three to four 

 feet. Smooth brome-grass (Bromus inermis) is one of the most 

 heavily rooted of grasses, and usually has a fairly long root system 

 to a depth of five to six feet in the prairie soils. 



The age of sod apparently affects the distribution of roots, as 

 they appear to gradually become shallower as the sod gets old and 

 compact. This is illustrated by the well-known weedy quack grass. 



