POLLINATION 205 



Primrose, Cowslip (see p. 176), and some species of Sorrel 

 (Oxalis) . 



(b) Long, intermediate, and short-styled forms (tri- 

 morphic),e. g. Purple Loosestrife (Lythrum Salicaria) , and 

 some species of Sorrel {Oxalis). 



As the pollen-grains are unable by their own efforts to 

 reach the stigmas, they must be carried by external agents, 

 the chief of which are the wind and animals. Flowers 

 differ in several important respects, according to the agent 

 employed in the transference of pollen. 



1. Flowers pollinated by the Wind (anemophilous : 

 Gr. anemos = wind, philos = loving) have usually the 

 following characteristics : 



The flowers are small, not showy, unscented, and without 

 honey ; the anthers are large and on long slender filaments ; 

 and sometimes, as in catkins, the whole inflorescence is 

 easily shaken by the wind. The pollen is abundant, dry, 

 and powdery. The stigmas are large and feathery, and 

 expose a large surface to catch the pollen ; but much of the 

 pollen never reaches the stigmas and is wasted. Many of 

 our forest trees are wind-pollinated, e. g. Pine, Larch, 

 Poplar, Hazel, Oak, Birch, Beech; also the Grasses and 

 Sedges, Docks, Plantains, Stinging Nettle, and Crowberry. 



2. Flowers pollinated by Animals (zoophilous : Gr. zdon 

 = an animal) are the more familiar and attractive species. 

 The most important pollinators are Insects, and the 

 flowers so pollinated are said to be entomophilous (Gr. 

 entomon = insect) . Flowers possess several features which 

 render them attractive to insects. They are usually 

 brightly coloured, often scented, and have nectaries. The 

 pollen is sticky, readily adheres to the bodies of insects, 

 and is often collected by thern as food. The stigmas are 

 small and frequently placed in a position favouring pollina- 

 tion by the insect visitor. Small animals like snails may 

 bring about pollination when crawling over certain flowers, 



