LINNEAN CLASSES AND ORDERS. 51 



NINETEENTH CLASS.— Syngenesia.* 



Stamens united by their anthers, which forrii 

 a tube, their filaments separate. Flowers com- 

 pound. Orders 5. 



Poliigamia JEquaVis. Polygamia Siiperjlua. 

 Polijgamia Frusti^anea. Polygamia Necessaria. 

 Polygamia Segregata. 



1 . Polygamia JEqualis has three subdivisions : 



"Florets all ligulate : 

 Ex. Succory, (Cichorium) and Dandelion, (Leon- 

 todon.) 



* Florets tubular. Flowers somewhat globular : 

 Ex. Thistle, (Carduus.) 



^ Florets tubular, erect, crowded ; Flowers 

 nearly level at the top : 

 Ex. Hemp-agrimony, (Eupatorium.) 



2, Polygamia SuperJIua, is subdivided thus : 



Florets of the radius or margin, obsolete or 

 wanting. 

 Ex. Tansy, (Tanacetum.) 



• " This is an extensive and most natural class, corresponding with 

 the Compositse of the natural aiTangemeut." — Hooker. 



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