THE ROOT SYSTEMS OF PLANTS 83 
which first forms 
when the seed bursts 
is known as the pri- 
mary root. From this 
primary root other 
roots develop, which 
are known as second- 
ary roots. When the 
primary root grows 
more rapidly than the 
secondary roots, the 
so-called taproot, 
characteristic of lu- 
cern, clover, and sim- 
ilar plants, is formed. 
When, on the other 
hand, the taproot 
grows slowly or ceases 
its growth, and the 
numerous secondary 
roots grow long, a 
fibrous root system 
results, which is char- 
acteristic of the ce- 
reals, grasses, corn, 
and other similar 
plants. With any 
type of root, the tend- 
ency of growth is 
A 
G 
Fig. 23. Alfalfa roots. 
