118 HETEROSTYLED DIMORPHIC PLANTS. CIIAP. Ill 



length, those of the short-styled being rather the longest; and 

 the anthers of both are seated in the mouth of the corolla. Nor 

 could I detect any difference in the size of the pollen-grains, 

 when dry or after being soaked in water. The stigmas of tho 

 long-styled form stand clear above the anthers, and the whole 

 pistil is longer than that of the short-styled, in about the ratio 

 of 3 to 2. 



The stigmas of the short-styled form are seated beneath the 

 anthers, and they are considerably shorter than those of the 

 long-styled form. This latter difference is the most important 

 one of any between the two forms. 



GlLIA (IPOMOPSIS) P0LCHELLA VEL AGGEEOATA (POLEMONI- 

 ACE.2E). 



Professor Asa Gray remarks with respect to this plant : " the 

 tendency to dimorphism, of which there are traces, or perhaps 

 rather incipient manifestations in various portions of the genus, 

 is most marked in (jf. a-igregatn.' * He sent me some dried 

 flowers, and I procured others from Kew. They differ greatly 

 in size, some being nearly twice as long as others (viz. as 30 to 

 17), so that it was not possible to compare, except by calculation, 

 the absolute length of the organs from different plants. More- 

 over, the relative position of the stigmas and anthers is variable : 

 in some long-styled flowers the stigmas and anthers were ex- 

 serted only just beyond the throat of the corolla; whilst in 

 others they were exserted as much as T % of an inch. I suspect 

 also that the pistil goes on growing for some time after the 

 anthers have dehisced. Nevertheless it is possible to class the 

 flowers under two forms. In some of the long-styled, the length 

 of pistil to that of the short-styled was as 100 to 82 ; but this 

 result was gained by reducing the size of the corollas to tho 

 same scale. In another pair of flowers the difference in length 

 between the pistils of the two forms was certainly greater, but 

 they were not actually measured. In the short-styled flowers 

 whether large or small, the stigma is seated low down within 

 the tube of the corolla. The papillae on the long-styled stigma 

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

 40. The filaments in some of the short-styled flowers were, to 

 those of the long-styled, as 100 to 25 in length, the free, or 



' Proc. American Acad. of Arts and Sciences,' June 14, 1870, p 275 



