114: HETEROSTYLED DIMORPHIC PLANTS. CHAP. III. 



visited by insects; these are adapted for self -fertilisa- 

 tion, though still capable of cross-fertilisation. Ac- 

 cording to Delpino, the Polygonaceae are generally 

 fertilised by the wind, instead of by insects as in the 

 present genus. 



LEUCOSMIA BURNETTIANA (THYMELLE). 



As Professor Asa Gray has expressed his belief * that 

 this species and L. acuminata, as well as some species in 

 the allied genus Drymispermum, are dimorphic or hetero- 

 styled, I procured from Kew, through the kindness of Dr. 

 Hooker, two dried flowers of the former species, an in- 

 habitant of the Friendly Islands in the Pacific. The pistil 

 of the long-styled form is to that of the short-styled as 100 

 to 86 in length; the stigma projects just above the threat 

 of the corolla, and is surrounded by five anthers, the tips 

 of which reach up almost to its base; and lower down, 

 within the tubular corolla, five other and rather smaller 

 anthers are seated. In the short-styled form, the stigma 

 stands some way down the tube of the corolla, nearly on a 

 level with the lower anthers of the other form: it differs 

 remarkably from the stigma of the long-styled form, in 

 being more papillose, and in being longer in the ratio of 

 100 to 60. The anthers of the upper stamens in the short- 

 styled form are supported on free filaments, and project 

 above the throat of the corolla, whilst the anthers of the 

 lower stamens are seated in the throat on a level with the 

 upper stamens of the other form. The diameters of a con- 

 siderable number of grains from both sets of anthers in 

 both forms were measured, but they did not differ in any 

 trustworthy degree. The mean diameter of twenty-two 

 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- 



* 'American Journal of Sci- 'Journal of Botany,' vol. iii., 

 ence,' 1865, p. 101, and Seemann's 1865, p. 305. 



