228 



THE FLOWER 



viduals. Examples of dimorphic flowers are the pretty 

 httle bluets {Houstonia ccerulea), the partridge berry {Mit- 

 chella repens), the swamp loosestrife {Lythrum lineare), 



and the English 

 cowslip. Of tri- 

 morphic flowers 

 we have exam- 

 ples in the wood 

 sorrel, and the 

 spiked loosestrife 

 {Lythrum. salica- 

 ria) of the gar- 

 dens. These 

 flowers were a 

 great puzzle to 

 botanists until the celebrated naturalist, Charles Darwin, 

 proved by a series of careful experiments that the seed pro- 

 duced by pollinating a dimorphous flower with its own pollen, 

 or with pollen from a 

 flower of similar form, are 

 of very inferior quality to 

 those produced by im- 

 pregnating a long-styled 

 flower with pollen from 

 a short-styled one, and 

 vice versa. 



449-451. — Three forms oi Lythrum salicaria. 



332. Wind Pollination. 

 — But the problem is 

 only half solved when a 

 plant has been rendered 

 incapable of impreg- 

 nating itself. Cross- 

 pollination, that is, the 

 transfer of pollen from a 452. 

 separate flower or plant, 

 has been rendered necessary, and provision must now be 

 made for the transportation. In many cases, of which the 



- Feathery stigmas of a grass adapted 

 to wind pollination. 



