96 HETEEOSTYLED DIMOEPHIC PLANTS. Chap. HI. 



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 move- 

 ment 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. grandAjlorwn,, 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 

 necessarily leave pollen on the proper surface of the 

 elongated stigmas ; and when they visit tlie short- 

 styled flowers, they will leave pollen on the upturned 

 stigmatic 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. 



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

 perfectly ; for the stamens in the two forms stand at 

 difierent heights, so that pollen from the anthers of 

 the longer stamens will adhere to one part of an 

 insect'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 



