310 GRASSES AND LEGUMES 



Quack (or witch) grass has a heavy, stoloniferous root system, dis- 

 tributed through four to six inches of surface soil in cultivated 

 fields or when first taking possession of the soil. As the sod becomes 

 old and tough the root stocks become shallower, and in an old sod 

 are mostly in the upper two inches. 



It is said that one reason why old meadows respond so quickly 

 to fertilizers is due to the rather shallow roots. Old pastures and 



FIG. 124. Orchard-grass representing a typical bunch grass. 



meadows also are seriously affected by drought, probably for the 

 same reason. 



Bunch and Sod Grasses. Certain of the cultivated grasses, 

 when sown thinly, form compact, isolated bunches which spread 

 very slowly. Orchard-grass and sheep fescue are excellent ex- 

 amples (Fig. 124). Other grasses, as blue-grass and brome-grass, 

 spread rapidly and form tough, compact sods. The principal differ- 



