Anemophily

Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Unlike entomophilous and zoophilous species, whose pollen is spread by insects and vertebrates respectively, anemophilous species do not develop scented flowers, nor do they produce nectar.

Male and female reproductive organs are generally found in separate flowers, the male flowers having a number of long filaments terminating in exposed stamens, and the female flowers having long, feather-like stigmas.

Pollen from anemophilous plants tends to be smaller and lighter in weight than pollen from entomophilous ones, with very low nutritional value to insects. However, insects sometimes gather pollen from staminate anemophilous flowers at times when higher protein pollens from entomophilous flowers are scarce. Also anemophilous pollens may also be inadvertently captured by bees' electrostatic field. This may explain why, though bees are not observed to visit ragweed flowers, its pollen is often found in honey made during the ragweed floral bloom. Other flowers that are generally anemophilous are observed to be actively worked by bees, with solitary bees often visiting grass flowers, and the larger honeybees and bumblebees frequently gathering pollen from corn tassels and other grains.

Almost all pollens that are allergens are anemophilous. Ragweed, the bane of many hayfever sufferers, is anemophilous. Its pollen has been found at sea hundreds of miles from its source. Spring hayfever often traces to pollens from birches.

Other common anemophilous plants are mosly grass species, conifers, sweet chestnuts, and members of the hickory family.