238 STUDY OF COMMON PLANTS. 



Wood-sage, Teucrium Canadense, L. 

 Riehweed, Collinsonia Canadensis, L. 

 Spearmint, Mentha viridis, L. 

 Wild mint, Mentha Canadensis, L. 

 Wild bergamot, Monarda fistulosa, L. 

 Skullcap, Scutellaria galericulata, L. 

 Motherwort, Leonurus Cardiaca, L. 

 Dead-nettle, Lamium maculatum, L. 

 Cultivated species of Salvia. 



Notwithstanding the fact that the Labiatse include some 

 twenty-six hundred species scattered over the entire globe, 

 they constitute a very natural group of plants ; that is, cer- 

 tain strongly marked characters are so uniformly present 

 that it would almost seem, as some botanical writers have 

 suggested, that all the species might be placed in one great 

 genus. Accordingly the distinction of genera in this 

 family becomes a difficult task. The modifications of the 

 floral structures in those species that have become most 

 dependent on the agency of insects for fertilization are 

 peculiarly interesting. The student may profitably devote 

 considerable time to the comparison of the various species 

 of Salvia, for example, with each other and with simpler 

 forms. Another interesting subject of investigation, and 

 one throwing additional light on the relationship of groups 

 that apparently have but little in common, is the develop- 

 mental history of the fruit, which is essentially the same 

 in this family as in the Boraginaceae. 



