252 



THE FLOWER. 



Adlumia there is only one strap-shaped filament on each side, 

 which is three-forked at the tip, each fork bearing an anther. One 

 of these trebled stamens is shown in Fig. 299. 



456. We have a similar case in some Hypericums and in Elo- 

 dea (Fig. 300), except that in these, while the floral envelopes are 



5-merous, the circles within them are 

 commonly 3-merous. The three 

 members of the andrcecium are nor- 

 mally placed, alternating with the 

 three members of the gynsecium with- 

 in, and without with three glands, 

 which probably replace an exterior 

 circle of stamens; but each member 

 as it developed has divided above in- 

 to three stamens (Fig. 301) ; each anther of which may be viewed 

 as homologous with a leaflet of a trifoliolate leaf (289). In the same 

 way are the false filaments placed between the petals and the real 

 stamens of Parnassia, partly divided into three in our P. Caroliniana 

 (Fig. 305), or into from 9 to 15 shorter glandular lobes in P. pa- 

 lustris. So each cluster of numerous stamens of the polyandrous 

 species of Hypericum (see Ord. Hypericacea?) doubtless arises 

 from the repeated chorisis of a single phyton, and is therefore anal- 

 ogous to a decompound leaf. The actual development of such a 

 cluster from a small protuberance, which in the forming flower-bud 

 stands in the place of a single phyton, and its repeated forkings 

 as it grows, have been traced by Duchatre, particularly in Malva- 

 ceous plants. 



457. Thus far we are sustained by a clear analogy in the or- 

 gans of vegetation. As the leaf frequently developes in the form 

 of a lobed, divided, or compound leaf, that is, as a cluster of par- 

 tially or completely distinct organs from a common base, so may 

 the stamen, or even the pistil, become compound as it grows, and 

 give rise to a cluster, instead of completing its growth as a solitary 

 organ : and it appears that the organogeny is strikingly similar in 

 the two cases. Nor is it very unusual for petals to become divided 

 or deeply lobed in the same manner ; as, for example, those of 

 Mignonette. In many cases, however, the multiplication takes 

 place in the opposite plane, so that the parts are situated one be- 



FIG. 300. Diagram (cross-section) of a flower of Elodea Virginica. 301. One of the three 

 stamen-clusters, consisting of a trebled stamen. 



