THE SMALL GRAINS 



rootlets or root-hairs which absorb water and liquid food 

 for the nourishment of the plant. There is little or no 

 growth of cereal roots after the beginning of flowering, in 

 which fact cereals differ from dicotyledonous plants. The 

 product of the root penetration in depth by the diameter 



of the lateral 

 spread of the 

 roots is called 

 the root coeffi- 

 cient (Fig. 1). 

 2. Culms. - 

 In cereals the 

 culms or stems 

 are round and 

 usually hollow 

 (48, 50, 53, 58), 

 with solid joints 

 or nodes. There 

 are both sheath 

 nodes and culm 

 nodes, the 

 former being 

 those usually ob- 

 served, showing 

 externally as 



FIG. 1. Cereal seedlings, showing the origin Swellings at the 

 of coronal or permanent roots, in one case some base of the leaf 

 distance above the seed. i , , r^\^ 



sheath. These 



nodes aid the plant in recovering an erect position and 

 therefore may be important characters in relation to lodg- 

 ing. From buds at the basal nodes of the culm additional 

 culms -may branch off, and from these culms still others 

 in the same way. Thus the process of " tillering " is ex- 



