272 



PLANT STRUCTURES 



146. Labiates. This great family (Labiates) and its alli- 

 ances represent more than ten thousand species. The con- 

 spicuous feature is the 

 zygomorphic flower, dif- 

 fering in this regard from 

 the Convolvulus forms, 

 which they resemble in 

 being tetracyclic and ani- 

 socarpic, as well as hypogy- 

 nous. The irregularity 

 consists in organizing the 

 mouth of the sympetalous 

 corolla into two "lips," 

 resulting in the labiate or 



FIG. 257. A conmjon dogbane (Apocynum).From "Field, Forest, aiid Wayside 



Flowerg," 



