ROOTS 



59 



and are sometimes referred to as tubers, but they must not be 

 confused with the tuber of the white potato, which is a fleshy 

 underground stem. Fleshy roots are used extensively for food. 

 The primary root is the first one that emerges from the seed. 

 The secondary roots are those which arise from the primary 



FlQ. 



35. — A grass plant showing the 

 fibrous root system. 



Fig. 36.' — Carrot showing fleshy roots. 



root. There are also many other kinds of roots to which special 

 names have been given, such as : (a) adventitious rooi^, which 

 are developed from runners, as in the case of the strawberry. 

 (&) Aerial roots, which grow from parts of the stem above 

 ground and may or may not reach the soil. They are produced 

 abundantly by the poison ivy and the trumpet creeper and serve 

 for climbing (Fig. 38). Some aerial roots grow do^vnward to 

 the soil and serve as braces or props, as in the case of com 

 (Fig. 39). (c) Roots of epiphytic plants having no connection 



