136 HBTEEOSTTLED DIMOEPHIO PLANTS. Chap. m. 



deserves notice that in the hoiaostyled genera, as I 

 am informed by Professor Asa Gray, the stamens are 

 either exserted or are included within the tube of the 

 corolla, in a nearly constant manner; so that this 

 character, which is not even of specific value in the 

 heterostyled species, is often of generic value in other 

 members of the family. 



