138 FUNDAMENTALS OF AGRICULTURE. 



marked, until the putting forth of the head. The gen- 

 eral appearance, however, makes it comparatively easy 

 to distinguish between wheat and oat plants at almost 

 any stage of their growth, except at a time when the 

 plants are quite young. 



The Roots. Wheat, upon germination, puts forth 

 a circle of three temporary roots at the point where 

 the radicle breaks through the seed coats in exactly the 

 same manner as oats. The permanent roots soon fol- 

 low, issuing from the nodes. Any node below the 

 surface of the soil, or even near the soil above the 

 surface, may throw out a whorl of roots. Upon con- 

 tinued growth these roots extend on all sides of the 

 plant, gradually going deeper until a depth of from 

 ten to eighteen inches is reached, depending largely on 

 the character of the soil. From this depth the roots 

 descend almost vertically, following almost invariably 

 the line of the least resistance. Thus we find the deep 

 roots occupying an abandoned passage made by a 

 worm or an old crawfish hole, or the space occupied 

 by the deep tap root of a preceding clover plant, or 

 even a crack formed sometime previously during some 

 excessively dry spell. These passages naturally fill up 

 easily and quickly during rains with the sediment from 

 the surface, and the soil within them is therefore less 

 firm and compact. It also probably contains a higher 

 percentage of available moisture and plant food. 



The Stalk (culm). As with oats, the culm of 

 wheat is a slender, elongated cylinder divided into un- 

 equal sections by joints or nodes. Unlike oats, how- 

 ever, the culm of wheat is more often more or less 

 filled with pith, and is also more variable in thickness 

 of walls and in color. 



The length of culm varies greatly with different va- 

 rieties, and although there is no definite relation be- 

 tween height and yield it is commonly thought, other 

 things being equal, that the longer the culm the higher 

 the yield of grain. Certain it is that the production 

 of a tall culm will more quickly deplete the fertility of 



