FLO WEES AND INSECTS 



129 



least two forms of flowers, wliicli differ from one another 

 in the relative lengtlis of their stamens and styles. In the 

 accompanying illustrations of Honslonia (see Fig. 135) it 

 is to be noticed that in one flower the stamens are short 

 and included in the tube, and the style is long and pro- 

 jecting, with the four stigmas exjiosed well above tlie 

 tube. In the 

 otlier flower the 

 relative lengths 

 are exactly re- 

 V e r s e d , t h e 

 stylo Ij e i n g 

 short and in- 

 cluded in the 

 tube, and tlie 

 stamens long 

 and projecting. 

 It appears that 

 the pollen f I'om 

 the sliort sta- 

 mens is most 

 effective upon 

 the stigmas of 

 the short styles, 

 and that the 

 jiollen from the 

 long stamens is 

 most efl'ective 

 upon the stig- 

 mas of tlie long styles ; and as short stamens and long 

 styles, or long stamens and short styles, are associated in 

 the same flower, the pollen must be transferred to some 

 other flower to find its ajipropriate stigma. Tliis means 

 that there is a dilference between the pollen of the short 

 stamens and that of the long ones. 



In some cases there are three forms of flowers, as in one 



Fig. 1.3.5. 

 flower 



Flowers of Houdoiiia, showing two forms of 

 In 1 there are short stamens and a long style ; 

 in 2 long stamens and short style. An insect visiting 1 

 wiJl receive a band of pollen abont the front part of its 

 body ; upon visiting 2 this band will nib against the 

 stigmas, and a fresli pollen band will be received upon 

 the hinder part of the body, which, npon visiting another 

 flower like No. 1, will brush against the stigmas. — 

 After Gray. 



