PERFECT FLOWERS 



57 



PARTRIDGE BERRY 

 (Dimorphic) 



some flowers and pis- 

 tils in others failing to 

 perfect. This is true, 

 also, of certain of the 

 primroses and foreign 

 species of the flax 

 ( Li n u m grandifiorum 

 and Linum flavium). 



Then there are flowers, called "trimorphic flow- 

 ers," which bear stamens and pistils of three dif- 

 ferent lengths ; but they so arrange matters among 

 themselves that the pollen from the long, the 

 medium, and the short stamens shall take effect 

 upon the long, the medium, and the short pistils, 

 respectively. The pickerel-weed (Pontederia) , the 

 purple spiked loosestrife (Ly thrum Salicaria), and 

 the wood-sorrel (Oxalis) furnish us with excellent 

 studies in trimorphism. 



STAMENS AND PISTILS DEVELOPING AT DIFFERENT 

 TIMES 



(Called "Dichogamy") 



If, as we have seen, the position of the anthers 

 and the stigmas assists greatly in the cross-fertilisa- 

 tion of the flowers, the time of their development 

 with reference to one another proves to be still more 

 effective. 



