POLLINATION AND FERTILIZATION 165 



1. Water, as an agent in carrying pollen, is of importance 

 to a number of water plants. The pollen floats on the water 

 to the stigmas. From a horticultural point of view, this 

 method of transportation is of little importance. 



2. Plants depending on winds for pollination are said 

 to be anemophilous. A considerable amount of the pollen 

 carried by wind is scattered and wasted. Consequently, 

 anemophilous plants produce enormous quantities of it. 

 The pollen-grains are commonly small with dry surfaces, 

 which prevent their sticking together. In many cases, 

 pollen-grains possess air bladders which facilitate wind 

 transportation. Various modifications of the usual form of 

 pistil are frequently present in cases in which wind is de- 

 pended on to carry the pollen. An example of this is shown 

 in the many branched spreading style of the hazelnut which 

 is especially adapted to catch and hold pollen-grains floating 

 in the air. Many of the nut-trees, such as the walnut, butter- 

 nut, and pecan depend on wind pollination. 



3. Insects are the most important carriers of pollen. 

 The common fruit-trees depend largely on bees for pollina- 

 tion. Such plants encourage bees to visit them by producing 

 a supply of nectar, which is usually secreted by nectar- 

 glands located well down at the base of the pistil or in the 

 lower parts of the flower, so that the bees, in order to obtain 

 the nectar secreted by the glands, must scramble down into 

 the flowers and get well dusted with pollen in doing so. 

 Flowers depending on insects for pollination, unlike wind- 

 pollinated ones, generally produce pollen-grains of good 

 size, comparatively speaking, and frequently the outside of 

 the grains is somewhat sticky. Such pollen-grains stick to 

 the hairy legs, wings, body, and head of the bee. In going 

 from flower to flower, the bee not only picks up pollen but 

 distributes it, for as it goes in search of nectar it brushes 

 some of the pollen against the stigmas, where numerous 

 grains stick, and pollination is accomplished. Flowers de- 



