274 



PLANT STKUCTURES 



hilaliate structure (Fig. 210, f, d, e), and suggesting the 

 name of the dominant family. The upper lip usually con- 

 tains two petals, and the lower three ; the two lips are some- 

 times widely separated, and sometimes in close contact, and 

 diifer widely in relative prominence. 



Associated with zygomorphy in this group is a frequent 

 reduction in the number of stamens, which are often four 

 (Fig. 212) or two. The whole structure is highly special- 

 ized for the visits of insects, and this great zygomorphic 

 alliance holds the same 

 relative position among 

 Sympetalae as is held 

 by the zygomorphic Le- 

 gumes among Archi- 

 chlamydeae. 



In the mint family, 

 as the Labiates are often 

 called, there are about 

 two thousand seven hun- 

 dred species, including 

 mint {Mentha) (Fig. 

 212), dittany (Cunila), 

 hyssop (Hyssopus), mar- 

 joram {Origanum), 



Fig. 259. Flowers of dead nettle {La- 

 miutn) : A, entire bilabiate flower ; 

 B, section of flower, showing rela- 

 tion of parts.— After Wakming. 



Fig. 260. A labiate plant ( Tencrium), show- 

 ing branch with flower clusters {A), and 

 side view of a few flowers (/?), showing 

 their bilabiate character.— After Bkiquet. 



