SEEDLINGS OF THE GRASS TYPE 



103 



unfolding its first leaves to the light, a zone, caUed a node, is 

 formed at its base about 2 inches under the surface of the soil, 

 and from this node and others soon forming above it, there arise 

 roots of a much larger and stronger type than those formed from 

 the radicle and from the stem in the region of the cotyledon. 

 These secondary roots, which are outgrowths of the plumule since 

 they arise from its nodes, constitute the permanent root system, 

 which as the name suggests remains active as an anchoring and 



Fig. 97. — Diagram showing the effect of planting Corn at different depths. 

 g, ground line; p, permanent root system, which always develops at about the 

 same distance under the surface; a, temporary region of the stem, which is 

 much longer in deep planting; k, kernel; /, temporary root system. Modified 

 from "Elementary Principles of Agriculture" by Ferguson and Lewis. 



absorptive system as long as the plant hves. After the permanent 

 roots are established (about 10 days after planting) the first 

 roots, which are known as the temporary roots since they serve 

 the plant only till the permanent roots are established, develop 

 no further and remain as vestigial structures until they finally 

 disappear. 



Also included among the temporary structures is the portion 

 of stem between the first node and kernel. (Fig. 96.) During 

 the early stage of germination, this stem portion performs two 



