COALESCENCE OF ITS ORGANS. 



257 



thus appears to be one simple organ), or to be toothed, loled, deft, 

 or parted, according to tbe degree in which the union is incom- 

 plete ; this language being employed just as in the case of the di- 

 visions of leaves (281). When the sepals are not united, the calyx 

 is said to be polysepalous ; and when the petals are distinct, the 

 corolla is said to be polypetalous ; that is, composed of several 

 petals. Examples of this union of the parts of the same circle 

 have already been shown, as respects the calyx and corolla (Fig. 

 287), and in the account of what is called the monopetalous divis- 

 ion of the exogenous natural orders further illustrations are given, 

 exhibiting this union in very different degrees. 



462. The union of the stamens occurs in various ways. Some- 

 times the filaments are combined, while the anthers are distinct. 

 When thus united by their filaments into one set, they are said to 

 be monadelplwus ; as in the Lupine, &c., (Fig. 307). When 

 united by their fila- 

 ments into two sets, 

 they are diadelphous 

 (Fig. 308), as in most 

 plants of the Pea tribe 

 (Leguminosse),where 

 nine stamens form 

 one set and the tenth 

 is solitary ; and in 

 Dicentra {Fig. 296, 



299), where the six stamens are equally combined in two sets. 

 When united or arranged in three sets or parcels, they are said to 

 be triadelphous, as in the common St. John's- wort, or if in several, 

 polyadelphous ; as in other Hypericums, in Tilia, &c. In some of 

 these instances, indeed, the stamens of each group have a common 

 origin, as we suppose (456) ; still, the same terms are employed 

 in botanical description, under whatever theoretical views. In 

 other cases, the filaments are distinct, or nearly so, and the anthers 

 united into a ring ; as in the vast order Compositae, or class Syn- 

 genesia of the Linnsean artificial system ; when the stamens are 

 said to be syngenesious (Fig. 309, 310). Again, in Lobelia, not 

 only are the anthers syngenesious, but the filaments are also com- 



FIG. 307. Monadelphous stamens of a Lupine. 308. Diadelphous stamens (9 and 1) from a 

 papilionaceous flower. Compare with the diagram, Fig. 232. 



FIG. 309. Syngenesious stamens of a flower of a Composita. 310. The tube of anthers laid 

 open. 



22* 



