anemophily

Type of pollination in which the pollen is carried on the wind. Anemophilous flowers are usually unscented, have either very reduced petals and sepals or lack them altogether, and do not produce nectar. In some species they are borne in catkins. Male and female reproductive structures are commonly found in separate flowers. The male flowers have numerous exposed stamens, often on long filaments; the female flowers have long, often branched, feathery stigmas.

Many wind-pollinated plants, such as hazel Corylus americana, bear their flowers before the leaves so that transport of pollen is not impeded. Since air movements are random, vast amounts of pollen are needed: a single birch catkin, for example, may produce over 5 million pollen grains.