ORGANS OF REPRODUCTION. 257 



Fig. 536. Fig. 537. Fig. 538. Fig. 539. 



Fig. 536. Syngenesious anthers of a species of Thistle Fig. 537. Mona- 



delphous stamens of Mallow Olalva). Fig. 538. Monadelphous stamens 



of Oxalis forming a tube round the pistil Fig. 539. Male flower of 



Jatropha Curcas. c. Calyx, p. Corolla, e. Stamens united by their 

 filaments into a tube, a, wliich occupies the centre of the flower as there is 

 no pistil. 



Mallow (Jig. 537), and Oxalis (fig. 538), the stamens are viona- 

 delphous. When this union takes place in a complete flower, the 

 coherent filaments necessarily form a tube or ring round the pistil 

 placed in their centre, as in the Oxahs (fig. 538). When the pistil 

 is absent, and the flower incomplete, the united filaments form a 

 more or less central column, as in Jatropha Curcas (fig. 539 a). 

 When the filaments unite so as to form two bundles, the stamens 

 are termed diadelphous, as 



in the Pea (fig. 540), Fu- Fig. 540. 



mitory (fig. 856), &c., in 

 which case the number of 

 filaments in each bundle 

 may be equal, as in the 

 Fumitory (fig. 856, or un- 

 equal, as in the Pea (fig. 

 540). The latter plant has 

 a papilionaceous corolla 

 with ten stamens, and in 

 such flowers it frequently 

 happens, that the filaments 

 are so united, that nine of 

 them form a bundle, while one remains free (fig. 540). When the 

 stamens are united by their filaments into three bundles, they are 

 triadelphous, as in some species of St. John's Wort (Hypericum) 

 (fig. 542) ; when in more than three, polyadelphous, as in the 

 Castor Oil plant (Ricinus) (fig. 543), Orange (fig. 541), and 

 s 



Fig. 540. Diadelphous stamens of the Sweet 

 Pea (Lathijrus), surrounding the pistil. 

 There are ten stamens, nine of which are 

 united and one free. 



