166 HETEROSTYLED TRIMOEPHIC PLANTS. CHAP. IV. 



dimorphic, like Primula, and therefore presents only two forms. 

 I received two dried flowers from Kew, which consisted of the 

 two forms ; in one the stigma projected far beyond the calyx, in 

 the other it was included within the calyx ; in this latter form 

 the style was only one-fourth of the length of that in the other 

 form. There are only six stamens ; these are somewhat gradu- 

 ated in length, and their aethers in the short-styled form stand 

 a little above the stigma, but yet by no means equal in length 

 the pistil of the long-styled form. In the latter the stamens 

 are rather shorter than those in the other form. The six 

 stamens alternate with the petals, and therefore correspond 

 homologically with the longest stamens of L. salicaria and L. 

 Onefferi. 



Ly thrum hyssopifolia.This species is said by Vaucher, but I 

 believe erroneously, to be dimorphic. I have examined dried 

 flowers from twenty-two separate plants from various localities, 

 sent to me by Mr. Hewett C. Watson, Professor Babington, and 

 others. These were all essentially alike, so that the species 

 cannot be heterostyled. The pistil varies somewhat in length, 

 but when unusually long, the stamens are likewise generally 

 long; in the bud the stamens are short; and Vaucher was 

 perhaps thus deceived. 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. 

 thymifolia. The stigma is included within the calyx, and stands 

 in the midst of the anthers, and would generally be fertilised 

 by them ; but as the stigma and anthers are upturned, and as, 

 according to Vaucher, there is a passage 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. salicaria, 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. hyssopffolia was not hetero- 

 styled, as such plants cannot habitually live isolated any bettei 

 than one sex of a dioecious species. 



' G<5ograph. Bot. de 1'Europe,' torn. vi. 1857, p. 157. 



