SEEDLINGS OF THE GRASS TYPE 103 
unfolding its first leaves to the light, a zone, called 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 
Fic. 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; t, temporary root system. Modified 
from ‘‘Elementary Principles of Agriculture’? by Ferguson and Lewis. 
absorptive system as long as the plant lives. 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 
