Wind and Water Pollination
Many flowers are pollinated without the aid of animals (insect, bird, or mammal). Some are pollinated as the currents of wind or water act as vectors. These flowers do not generally attract animal pollinators.
Wind pollinator flowers may be small, no petals, and no special colors, odors, or nectar. These plants produce enormous numbers of small pollen grains. For this reason, wind-pollinated plants may be allergens, but seldom are animal-pollinated plants allergenic. Their stigmas may be large and feathery to catch the pollen grains. Insects may visit them to collect pollen, but usually are ineffective pollinators and exert little natural selection on the flowers. Anemophilous, or wind pollinated flowers, are usually small and inconspicuous, and do not possess a scent or produce nectar. The anthers may produce a large number of pollen grains, while the stamens are generally long and protrude out of flower. There are also examples of ambophilous (pollinated by two different classes of pollinators) flowers which are both wind and insect pollinated.
Most conifers and about 12% of the world’s flowering plants are wind-pollinated. Wind pollinated plants include grasses and their cultivated cousins, the cereal crops, many trees, the infamous allergenic ragweeds, and others. All release billions of pollen grains into the air so that a lucky few will hit their targets.
Wind-pollinated flowers are typically:
- No bright colors, special odors, or nectar
- Most have no petals
- Stamens and stigmas exposed to air currents
- Large amount of pollen
- Pollen smooth, light, easily airborne
- Stigma feathery to catch pollen from wind
- May have staminate and pistillate flowers, may be monoecious or dioecious
- Usually single-seeded fruits, such as oak, grass, birch, poplar, hazel, dock, cat-tail, plantain, and papyrus
Water pollinated plants are aquatic. Pollen floats on the water’s surface drifting until it contacts flowers. This is called surface hydrophily, but is relatively rare (only 2% of pollination is hydrophily). This water-aided pollination occurs in waterweeds and pondweeds. In a very few cases, pollen travels underwater. Most aquatic plants are insect-pollinated, with flowers that emerge from the water into the air.
Many of the water-pollinated plants have become invasive throughout the United States. To learn more, visit these invasive species websites: