166 HETEEOSTYLED TEIMOEPHIC PLANTS. CHAP. IV. 



long, the stamens are likewise generally long; in the bud 

 the stamens are short; and Vaucher was perhaps thus de- 

 ceived. There are from six to nine stamens graduated in 

 length. The three stamens, which vary in being either 

 present or absent, correspond with the six shorter stamens 

 of L. salicaria and with the six which are always absent in 

 L. thy mif olia. The stigma is included within the calyx, 

 and stands in the midst of the anthers, and would gen- 

 erally be fertilised by them ; but as the stigma and anthers 

 are upturned, and as, according to Vaucher, there is a pas- 

 sage left in the upper side of the flower to the nectary, 

 there can hardly be a doubt that the flowers are visited 

 by insects, and would occasionally be cross-fertilised by 

 them, as surely as the flowers of the short-styled L. sali- 

 caria, the pistil of which and the corresponding stamens 

 in the other two forms closely resemble those of L. hys- 

 sopifolia. According to Vaucher and Lecoq,* this species, 

 which is an annual, generally grows almost solitarily, 

 whereas the three preceding species are social ; and this fact 

 alone would almost have convinced me that L. hyssopifolia 

 was not heterostyled, as such plants cannot habitually live 

 isolated any better than one sex of a dioecious species. 



We thus see that within this genus some species are 

 heterostyled and trimorphic; one apparently heterostyled 

 and dimorphic, and one homostyled. 



Nescea verticillata. I raised a number of plants from 

 seed sent me by Professor Asa Gray, and they presented 

 three forms. These differed from one another in the pro- 

 portional lengths of their organs of fructification and in 

 all respects, in very nearly the same way as the three forms 

 of Lythrum Grcefferi. The green-pollen grains from the 

 longest stamens, measured along their longer axis and not 

 distended with water, were T^f? of an inch in length ; those 

 from the mid-length stamens rinsir, and those from the 

 shortest stamens -ri'-jnr of an inch. So that the largest pol- 

 len-grains are to the smallest in diameter as 100 to 65. 

 This plant inhabits swampy ground in the United States. 

 According to Fritz Miiller, f a species of this genus in St. 

 Catharina, in Southern Brazil, is homostyled. 



* 'Geograph. Bot. de 1'Europe,' torn, vi., 1857, p. 157. 

 t 'Bot. Zeitung,' 1868, p. 112. 



