ENCYCLOPEDIA INTERNATIONAL

Wind pollination is characteristic of plants which have inconspicuous flowers and which usually lack fragrance and insect-attracting nectar. An abundant amount of dry, light pollen is produced with is carried by the wind, often great distances, to receptive stigmas. Masses of such pollen in the air area a prime cause of human allergy reactions, such as hay fever. Grasses, ragweed, pine, birch, and oak are examples of wind-pollinated plants.

THE NEW ENCYCLOPEDIA BRITANNICA

Pollination by wind, although prevalent in the conifers and cycads, is less common in flowering plants. Plants that depend on wind pollination produce copious quantities of light, powdery pollen that can be blown a considerable distance; but even so, and individual stigma is likely to be hit by only one or two grains. To facilitate exposure to the wind, the flowers often bloom before the leaves come out in the spring, or they may grow high up on the tree or plant. Stigmas tend to be long and lobed to provide a large area for catching pollen grains, and plants of one species frequently grow in dense populations. Wind flowers are usually inconspicuous and devoid of the fragrance, colours, and nectar that attract insects.