Chap. VII. GYNO-DICECIOUS PLANTS. 305 



complete abortion of the male organs. I shall pre- 

 sently discuss the cause of the smaller size of the 

 female corolla. 



Scahiosa arvensis (Dipsacefe).— It has been shoTvn by H. MUUer 

 that this species exists ia Germany under an hermaphrodite and 

 female form.* In my neighbourhood (Kent) the female plants 

 do not nearly equal in number the hermaphrodites. The stamens 

 of the females vary much in their degree of abortion ; in some 

 plants they are quite short and produce no pollen ; in others 

 they reach to the mouth of the corolla, but their anthers are not 

 half the proper size, never dehisce, and contain but few pollen- 

 grains, these being colourless and of small diameter. The her- 

 maphrodite flowers are strongly proterandous, and H. Miiller 

 shows that, whilst all the stigmas on the same flower-head are 

 mature at nearly the same time, the stamens dehisce one after 

 the other ; so that there is a great excess of pollen, which serves 

 to fertilise the female plants. As the production of pollen by 

 one set of plants is thus rendered superfluous, their male organs 

 have become more or less completely aborted. Should it be 

 hereafter proved that the female plants yield, as is probable, 

 more seeds than the hertnaphrodites, I should be inclined to 

 .extend the same view to this plant as to the Labiatse. I have 

 also observed the existence of two forms in our endemic S. 

 succiia, and in the exotic S. atro-purpurea. In the latter plant, 

 differently to what occurs in S. arvensis, the female flowers, 

 especially the larger circumferential ones, are smaller than those 

 of the hermaphrodite form. According to Lecoq, the female 

 -flower-heads of ;S. siwctsa are likewise smaller than those of 

 what he calls the male plants, but which are probably her- 

 maphrodites. 



Echium vulgare (Boraginese). — The ordinary hermaphrodite 

 form appears to be proterandrous, and nothing more need be said 

 about it. The female differs in having a much smaller corolla 

 and shorter pistil, but a well-developed stigma. The stamens 



* • Befruohtung der Blumen,' and females co-exiat ; it is, how- 



&o., p. 368. The two forms occur ever, possible that lie may have 



not only in Germany, but in been deceived by the flowers being 



England and France. Lecoij, so atrongly proterandrous. From 



('Geographie But.' 1857, torn. vi. what Leooq says, & succisa like- 



pp. 473, 477) says that male wise appears to occur under two 



plants as well as hermaphrodites foims in Fiance. 



