120 HETEROSTYLED DIMORPHIC PLANTS. CHAP. Ill 



below the other, the uppermost just protruding from the throat 

 of the corolla. In Phlox subulata alone he has " seen both long 

 and short styles ; and here the short-styled plant has (irrespec- 

 tive of this character) been described as a distinct species (P. 

 nivalis, P. Ilentzii), and is apt to have a pair of ovules in each 

 cell, while the long-styled P. subuJata rarely shows more than, 

 one.''* Some dried flowers of both forms were sent me by him, 

 and I received others from Kew, but I have failed to make 

 out whether the species is heterostyled. In two flowers of 

 nearly equal size, the pistil of the long-styled form was twice as 

 long as that of the short-styled ; but in other cases the differ- 

 ence was not nearly so great. The stigma of the long-styled 

 pistil stands nearly in the throat of the corolla ; whilst in the 

 short-styled it is placed low down sometimes very low down 

 in the tube, for it varies greatly in position. The stigma is 

 more papillose, and of greater length (in one instance in the 

 ratio of 100 to 67), in the short-styled flowers than in the 

 long-styled. My son measured twenty pollen-grains from a 

 short-styled flower, and nine from a long-styled, and the 

 former were in diameter to the latter as 100 to 93; and this 

 difference accords with the belief that the plant is hetero- 

 styled. But the grains from the short-styled varied much in 

 diameter. He afterwards measured ten grains from a distinct 

 long-styled flower, and ten from another plant of the same form, 

 and these grains differed in diameter in the ratio of 100 to 90. 

 The mean diameter of these two lots of twenty grains was to 

 that of twelve grains from another short-styled flower as 100 to 

 75 : here, then, the grains from the short-styled form were con- 

 siderably smaller than those from the long -styled, which is the 

 reverse of what occurred in the former instance, and of what is 

 the general rule with heterostyled plants. The whole case is 

 perplexing in 'the highest degree, and will not be understood 

 until experiments are tried on living plants. The greater length, 

 and more papillose condition of the stigma in the short-styled 

 than in the long-styled flowers, looks as if the plant was hetero- 

 styled ; for we know that with some species for instance, Leu- 

 cosmia and certain Eubiacese the stigma is longer and more 

 papillose in the short -styled form, though the reverse of thia 

 holds good in Gilia, a member of the same family with Phlox. 

 The similar position of the anthers in the two forms is some- 



Troc. American Acad. of Arts and Sciences,' Juno 11. 1S70. j> 218. 



