Trees produce seeds just as smaller plants do. Their flowers or cones are fertilized by the wind, or insects or birds. But a parent tree takes up large amounts of water from the area around it, and its leaves prevent sunlight from reaching the ground beneath, so it is important that all the seeds do not fall directly beneath the tree. Some trees produce fruits that are eaten by birds or animals and carried far away in their digestive systems. Others bear seeds that have “wings” and can be blown far away by the wind.

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.

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. 

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