CiiAP. III. PHLOX SUSXTLATA. 119 



unattaolied portion being alone measirred ; but this ratio can- 

 not be trusted, owing to the great variability of tbe stamens. 

 The mean diameter of eleven pollen-grains from loijig-styled 

 flowers, and of twelve from the short-styled, was exactly the 

 same. It follows from these several statements, that the dif- 

 ference in length and state of surface of the stigmas in the 

 flowers is the sole reliable evidence that this species is hetero- 

 styled; for it would be rash to trust to the difference in the 

 length of the pistils, seeing how variable they are. I should 

 have left the case altogether doubtful, had it not been for the 

 observations on the following species; and these leave little 

 doubt on my mind that the present plant is truly heterostyled. 

 Professor Gray informs me that in another species, O. coronopi- 

 Mia, belonging to the same section of the genus, ho can see no 

 sign of dimorphism. 



GiLiA (Leptosiphon) mickantha. 



A few flowers sent me from Kew had been somewhat injured, 

 so that I cannot say anything positively with respect to the 

 position and relative length of the organs in the two forms. 

 But their stigmas differed almost exactly in the same manner as 

 in the last species ; the papillsB on the long-styled stigma being 

 longer than those on the short-styled, in the ratio of 100 to 42. 

 My son measured nine pollen-grains from the long-styled, ami 

 the same number from the short-styled form; and the mean 

 diameter of the former was to that of the latter as 100 to 81. 

 Considering this difference, as well as that between the stigmas 

 of the two forms, there can be no doubt that this species is 

 heterostyled. So probably is GiUa nudicauUs, which likewise 

 belongs to the Leptosiphon section of the genus, for I hear from 

 Professor Asa Gray that in some individuals the style is very 

 long, with the stigma more or less exserted, whilst in others it 

 is deeply included within the tube ; the anthers being alway.i 

 seated in the throat of the corolla. 



Phlox subulata (Polbmoniage.*). 



Professor Asa Gray informs me that the greater number of 

 the species in this genus have a long pistil, with the stigma 

 more or less exserted ; whilst several other species, especially the 

 annuals, have a short pistil seated low down within the tube of 

 the corolla. In all the species the anthers are arranged one 

 9 



