THE CLASSIFICATION OF PLANTS. 409 



Class 15, Tetr adynamia, includes plants -w-ith six stamens, of 

 which four are long and two short — or, in other 

 words, tetradynamous ; as in the Wallflower and 

 Cruciferous Plants generally. {Fig. 546.) This 

 class corresponds to the natural order Cruciferte. 



The names of the two latter classes are derived fi-om the 

 Greek, and signify in the former class that the two longer, and 

 in the latter that the four longer stamens, are more powerful than 

 the shorter. 



The three next classes are characterised by the connection of 

 the stamens into one or more bundTes. Their names are derived 

 from the combination of the Greek numeral expressing the 

 number of bundles, with the termination adelphia or brother- 

 hood, which is used metaphorically for a bundle or parcel ; 

 thus : — 



Class 16. Monadelphia, includes all plants the stamens of which 

 are united by their filaments into one bundle or 

 brotherhood, as in the plants of the Mallow Order, 

 Geranium, &c. {Fig. 537.) 



Class 17. Diadelphia, those with the filaments united into two 

 bundles or brotherhoods, as in the Pea and many 

 other Papilionaceous flowers. Fumitory, &c. {Fig. 

 540.) 



Class 18. PolyadeJphia, those with the stamens united into 

 more than two bundles or brotherhoods, as in the 

 St. John's-wort, Castor Oil Plant, Orange, &c. 

 {Figs. 541, 542.) 



In the next class the character is derived from the coherence 

 of the anthers, and the name is derived from two Greek words, 

 signifying to grow together ; thus : — 



Class 19. Syngenesia, includes all plants the flowers of which 

 have their anthers united into a tube or ring, the 

 filaments being distinct, as in all Composite Plants. 

 {Fig. 536.) 



The character of the next class is founded on the union of the 

 stamens to the pistil. 



Class 20. Gynandria. This includes all plants in which the 



stamens and pistil are united together into one 



column, as in the Orchis Order, &c. {Fig. 534.) 



The name of this class is derived from two Greek words, one of 



-which, gynia, in combination gyn, is used metaphorically for pistil, 



and the other, andria, as already mentioned, means male or stamen. 



In the preceding twenty classes the flowers all contain both 



stamens and pistil. In the three foDowing classes the stamens 



