TYPES OF ROOT SYSTEMS 
139 
their numerous fine branches form a system resembling a fine 
brush when the dirt is washed away. 
root system is common among weeds, trees, and 
many cultivated plants. 
In addition to the un- 
derground roots, some of the Grasses, as Corn 
illustrates, develop prop or brace roots, which 
grow out from nodes above the ground into 
which they finally reach to afford additional an- 
chorage. 
Fic. 124.— Young Shell- 
bark Hickory, showing the 
tap-root. After Farmers’ 
Bulletin 178, U. 8. Dept. 
of Agriculture. 
the next year. 
However, brace roots are not neces- 
sarily an accompaniment 
of fibrous root systems, 
for they may occur in 
connection with other 
kinds of root systems. 
The tap-root system, in 
which there is one large 
main root from which 
small lateral branches 
arise, is typical of the 
Alfalfa, Red Clover, 
Beets, Dandelion, and 
numerous other plants. 
Tap-roots usually grow 
directly downward, pen- 
etrating into the deeper 
layers of the soil where 
more moisture is avail- 
able. (Fig. 123.) For 
this reason, the tap-root 
(Fig. 122.) This type of 
~ 
! 
/ 
Fie. 123. — 
Alfalfa, a plant 
with a promi- 
nent tap-root. 
system is best adapted for dry regions 
and is, therefore, characteristic of drought 
resistant plants. 
Although the tap-root 
is more common among herbaceous 
plants, it occurs, nevertheless, among 
trees, where it often interferes with trans- 
planting, as in case of Hickories, Oaks, 
and Maples. 
(Fig. 124.) 
Tap-roots are also convenient storage 
organs in which food is stored for the growth of the new shoot 
This fact is well illustrated in Alfalfa, Clover, 
