118 HETEROSTYLED DIMORPHIC PLANTS. Chap. III. 



differences are not well pronounced in the two forms. 

 Linum grandiflorum shows us that a plant may be hetero- 

 styled in function in the highest degree, and yet the two 

 forms may have stamens of equal length, and pollen-grains 

 of equal size. In the present species of Cordia, the stamens 

 of both forms are of nearly equal 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 the 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 be- 

 neath 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. 



Gilia (Ipomopsis) pulchella vel aggregata (Polemoni- 



aceje). 



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 por- 

 tions of the genus, is most marked in O. aggregata" * 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 pos- 

 sible to compare, except by calculation, the absolute length 

 of the organs from different plants. Moreover the rela- 

 tive 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 & of an inch. I sus- 

 pect 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 the same scale. In another pair of 



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

 p. 275. 



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