106 GERMINATION OF SEEDS: SEEDLINGS 
be put deeper in the soil by adding dirt around the plant. In 
semi-arid regions where a deep permanent root system is desired, 
the ground is often listed, that is, plowed into deep furrows, and 
the Corn planted in the bottom of the furrows. Then as the 
furrows are gradually 
filled in cultivation, the 
permanent roots are 
buried deeper in the 
soil, where there is a 
chance for moisture 
during drought. In this 
same connection, one 
can see some advan- 
tage in drilling small 
grains in that the roots 
of the plants will be 
buried deeper as the 
dirt from the ridges is 
carried into the drill 
furrows during rains 
and thaws. 
In the small grains, 
such as Wheat, Oats, 
Barley, etc., although 
the temporary system 
Fic. 100. — Stages in the development of a is just as prominent as 
Common Bean seedling. A, the cotyledons in Corn, there is, how- 
(c) being pulled out of the ground by the hy- ever, a difference of 
pocotyl ve t, eee o ae eo ee ; minor importance to be 
im ine. OCO Tal - : 
oe os Re es ee Pee ae noted in the number 
and spread apart, thus giving freedom to the of primary roots, which 
plumule (p). C, stage with plumule develop- is one in Corn but two 
ing stem and leaves (J), root system much en- or more in the small 
larged by secondary roots (s), and cotyledons grains. (Fig. 98.) 
(c) shrinking through loss of stored food. 
The presence of the 
temporary system, although occurring in other plants, is a not- 
able feature of the Grass seedlings. Another feature to be noted 
is that the cotyledon remains where the seed was placed in 
planting, that is, it is not pushed up out of the soil by an elong- 
ating hypocotyl. 
