THE ROOT SYSTEMS OF PLANTS 



83 



which first forms 

 when the seed bursts 

 is linown as the pri- 

 mary root. From this 

 primary root other 

 roots develop, which 

 are linown as second- 

 ary roots. Wlien 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 



I'iG. 23. Alfalfa roots. 



