Si&a , LINNAIAN CLASSES. 



as in Jristolochia, Engl. Bot. f. 398, or from the Style^ 

 as in the Orchis family. The Passion-flower is 

 wrongly put by Linnaeus and others into this Class, 

 as its stamens merely grow out of an elongated re- 

 ceptacle or column supporting the Germen. 



21. MoNOEciA. Stamens and Pistils in separate flow- 

 ers, but both growing on the same plant, or, as the 

 name expresses, dwelling in one house, as the Oak, 

 Hazle, and Fir. 



22. DioEciA. Stamens and Pistils not only in separate 

 flowers, but those flowers situated on two separate 

 plants, as in the Willow, Hop, Yew, &c. 



These two last Classes are natural when the barren 

 flowers have, besides the difference in their essential 

 organs, a difierent structure from the fertile ones in 

 other respects ; but not so when they have the same 

 structure, because then both organs are liable to meet 

 in the same flower. In some plants, as Rhodiola^ 

 Erwl. Bot. t. 508, each flower has always the rudi- 

 ments of the other organ, though generally inefficient. 



23. PoLYGAMiA. Stamens and Pistils separate in some 

 flowers, united in others, either on the same plant, or 

 on two or three different ones. 



This Class is natural only when the several flowers 

 have a different structure, as those of Jtriplex ; but 

 in this genus the Pistil of the united flower scarcely 

 produces seed. If, w^ith Linnaeus, we admit into 

 Polygamia every plant on which some separated bar- 



