448 



HUTCHINSON'S POPULAR BOTANY 



even when the nectar-gland only was removed. Mr. Sugden noticed also 

 that black bees, which visited the free and unmutilated flowers in large 

 numbers, hardly ever touched an anther or pistil, so that they were of 

 no use as pollinating agents. The visits of wild bees and the common 

 honey-bee were equally profitless to the flowers ; and even when a humble- 

 bee hit pollen in its 

 plunges to get at the nec- 

 tar, it left the plant after 

 trying a single flower. "With 

 humming-birds the case was 

 quite different. Every time 

 one of these little creatures 

 thrust his arrowy beak into 

 a flower of the first stage, 

 his head would strike the 

 anthers and become dusted 

 with pollen. On visiting a 

 flower in the second stage 

 i.e. after the withering of 

 the crown of anthers the 

 bird's head would come in 

 contact with the exposed 

 stigma, with the inevitable 

 result that some of the pollen 

 would be left upon it. 



Of the plants which lay 

 themselves out for cross- 

 fertilization, but which do 

 not invite the co-operation 

 of small animals, some em- 

 ploy water as their agent, 

 and others the wind. Ex- 

 ternal aid for the purpose 

 in question may therefore 

 be of three kinds, and the 

 plants which require those 

 agencies to bring their re- 

 productive elements to- 

 gether may be grouped 

 under one or another of the following heads : ZoophUce, or animal-lovers ; 

 Hydrophttce, or water-lovers ; and Anemophilce, or wind-lovers. 



Wind- and water-pollinated plants are rigid economists, except in the 

 matter of pollen.. They have no attractive odours, no bright petals, no 

 nectar. Birds and insects may be allured by these things, but not so wind 



Photo by] 



FIG. 552. ASPEN (Populus tremula). 



IE. Step. 



The simple (lowers are borne i 

 to allow pollination by the lea 



long catkins, which appear be/ore the leaves 

 es. Those shown in ttie photo are the male 

 catkins. 



