Chap. III. MENYANTHES TBIFOLIATA. 115 



grains from the short-styled flower was to that of twenty-four 

 grains from the long-styled, as 100 to 99. The anthers of 

 the upper stamens in the short-styled form appeared to be 

 poorly developed, and contained a considerable number of 

 shrivelled grains which were omitted in striking the above 

 average. Notwithstanding the fact of the pollen-grains from 

 the two forms not differing in diameter in any appreciable 

 degree, there can hardly be a doubt from the great difference in 

 the two forms in the length of the pistil, and especially of the 

 stigma, together with its more papillose condition in the short- 

 styled form, that the present species is truly heterostyled. This 

 case resembles that of lAnum grandiflorum, in which the sole 

 difference between the two forms consists in the length of the 

 pistils and stigmas. From the great length of the tubular 

 corolla of Leucosmia, it is clear that the flowers are cross- 

 fertilised by large Lepidoptera or by honey-sucking birds, and 

 the position of the stamens in two whorls one beneath the 

 other, which is a character that I have not seen in any other 

 heterostyled dimorphic plant, probably serves to smear the 

 inserted organ thoroughly with pollen. 



MkNYANTHES TBLFOMATA (GBNTIANBiE). 



This plant inhabits marshes : my son William gathered 247 

 flowers from so many distinct plants, and of these 110 were 

 long-styled, and 137 short-styled. The pistil of the long-styled 

 form is in length to that of the short-styled in the ratio of about 

 3 to 2. The stigma of the former, as my son observed, is deci- 

 dedly larger than that of the short-styled ; but in both fonns it 

 varies much in size. The stamens of the short-styled are almost 

 double the length of those of the long-styled; so that their 

 anthers stand rather above the level of the stigma of the long- 

 styled form. The anthers also vary much in size, but seem 

 often to be of larger size in the short-styled flowers. My son 

 made with the camera many drawings of the pollen-grains, 

 and those from the short-styled flowers were in diameter in 

 nearly the ratio of 100 to 84 to those from the long-styled 

 flowers. I know nothing about the capacity for fertilisation in 

 the two forms ; but short-styled plants, living by themselves in 

 the gardens at Kew, have produced an abundance of capsules, 

 yet the seeds have never germinated ; and this looks as if the 

 short-styled form was sterile with its own pollen. 



