268 



THE FLOWER. 



margins of the carpellary leaf. In many species of Gentian, as 

 also in Obolaria and Bartonia, of the same 

 family, the whole internal face of a dicar- 

 pellary ovary is thickly ovuliferous. 



503. Perhaps the parietal placentae in 

 Parnassia (Fig. 552) are borne on the 

 midribs of the carpels, for they are directly 

 under the stigmas, instead of alternate 

 with them, as they normally should be. The same thing occurs 

 in Poppies and man}' other Papaveraceae, also in some Cruciferte ; 

 and in some of the cases each stigma 

 is more or less two-lobed. This sug- 

 gests the explanation, 1 here probably 

 the true one, which supposes that the 

 placentae are borne on the leaf-margins 

 in the normal way, but that each 

 stigma is two- parted (as if the carpel- 

 lary leaf were deeply notched at the 

 apex, and so its two stigmatic leaf- 

 margins separate, as Drosera illus- 

 trates, Fig. 553), and that the two 

 half-stigmas of adjacent carpels have 

 coalesced into one body, which would 

 of course stand over the parietal placentae beneath. Each stigma 

 in such a case, as well as each parietal placenta, would consist 

 of the united margins of two adjacent carpels. 



2. IN GYMNOSPERMS. 



504. GYMNOSPERMOTJS (that is, naked-seeded) plants are so 

 named because the ovules, or bodies which are to become seeds, 

 are fertilized by direct application of the pollen, which reaches 

 and acts upon the nucleus of the ovule itself, not through the 

 mediation of stigma and style. In the structure of their flowers, 

 these plants are of a low or simplified type, in some respects not 

 obviously homologous with the Angiosperms which now consti- 

 tute the immense majority of phaenogamous plants. But, up to 

 a comparatively late geological period, Gymnosperms appear to 

 have been the only flower-bearing plants. They are represented 



1 Given by Brown, in the Plantae Javanicae Rariores, above referred to. 



FIG. 551. Transverse section of an ovary of Nymphaea odorata, the carpels ovulifer- 

 ous over the whole interior surface. 



FIG. 552. Pistil of Parnassia, with ovary transversely divided. 



FIG. 553. Pistil of Drosera filiformis, with ovary transversely divided. 



