102 GERMINATION OF SEEDS: SEEDLINGS 
of a plant’s life-cycle into successive stages is somewhat. artificial, 
for the stages so overlap that they can not be separated. In this 
presentation we are chiefly concerned with the seedling stage — 
Fic. 96.— A later stage of the Corn seed- 
ling. g, ground linc; p, plumule; a, first 
node with permanent root system; b, portion 
of stem between the first node and kernel; 
k, kernel; 7, radicle or primary root; s, sec- 
ondary roots of the primary root system; 
d, permanent root system; c, coleoptile. 
About half natural size. 
the stage in which plants 
present differences that 
sometimes must be reck- 
oned with in choosing 
proper methods of plant- 
ing and cultivating, and 
that often explain the 
peculiar features of the 
plant in the adult stage. 
Among our cultivated 
plants there are four rather 
distinct types of seedlings 
as those of the Grasses, 
Onion, Beans, and Peas 
illustrate. 
Seedlings of the Grass 
Type. — The seedlings of 
all Grasses are so similar 
in type that their essential 
features may be learned 
by studying the seedling 
stage of Corn. From Fig- 
ure 95, showing the de- 
velopment of the Corn 
seedling, it is seen that the 
radicle develops directly 
downward, forming the 
first root called primary 
root from which secondary 
roots arise as branches. 
However, not all second- 
ary roots arise at this time 
from the radicle, for some 
often grow out from the stem just above or below the cotyledon. 
The plumule, although developing more slowly at first than the 
radicle, soon breaks through its sheath-like covering (coleoptile) 
and rapidly elevates its leaves to the light. As the plumule is 
