96 HETEROSTYLED DIMORPHIC PLANTS. Chap. III. 



by the ring of broad filaments, and would never have 

 received any pollen. As it is, the styles diverge and 

 pass out between the filaments. After this movement 

 the short stigmas lie within the tube of the corolla; 

 and their papillous surfaces being now turned upwards 

 are necessarily brushed by every entering insect, and 

 thus receive the required pollen. 



In the long-styled form of L. grandiflorum, the 

 almost parallel or slightly diverging anthers and 

 stigmas project a little above the tube of the somewhat 

 concave flower; and they stand directly over the open 

 space leading to the drops of nectar. Consequently 

 when insects visit the flowers of either form (for the 

 stamens in this species occupy the same position in 

 both forms), they will get their foreheads or proboscides 

 well dusted with the coherent pollen. As soon as they 

 visit the flowers of the long-styled form they will neces- 

 sarily leave pollen on the proper surface of the elon- 

 gated stigmas; and when they visit the short-styled 

 flowers, they will leave pollen on the upturned stig- 

 matic surfaces. Thus the stigmas of both forms will 

 receive indifferently the pollen of both forms; but we 

 know that the pollen alone of the opposite form causes 

 fertilisation. 



i 



In the case of L. perenne, affairs are arranged more 

 perfectly; for the stamens in the two forms stand at 

 different heights, so that pollen from the anthers of 

 the longer stamens will adhere to one part of an in- 

 sect's body, and will afterwards be brushed off by the 

 rough stigmas of the longer pistils; whilst pollen from 

 the anthers of the shorter stamens will adhere to a 

 different part of the insect's body, and will afterwards 

 be brushed off by the stigmas of the shorter pistils ; and 

 this is what is required for the legitimate fertilisa- 

 tion of both forms. The corolla of L. perenne is more 



