In their urge for survival, the seed-bearing trees hit…

““In their urge for survival, the seed-bearing trees hit upon countless different devices for carrying pollen from one flower to another, but essentially the methods fall into two main categories. The first is wind-pollination, which requires the presence of light, small, dry pollen grains, easily shaken from the stamens, or male flowers. To receive the tiny bits of pollen that are blown about by the wind, the stigmata of flowers must be long, or feathery, or sticky, or so constructed as to trap the fine dust. All conifers are pollinated this way, as are the poplar, ash, birch, oak, beech, and certain other species. But since this method is so haphazard, a disproportionately high percentage of pollen is wasted and these trees must produce immense quantities of pollen in order that even a tiny amount will be effective. Scientists have estimated that a single stamen of a beech tree, for example, may yield 2,000 grains, while the branch system of a vigorous young birch can produce 100 million grains a year. One pine or spruce cone alone releases between 1 and 2 million grains of pollen into the air: In Sweden, which is covered with spruce forests, an estimated 75,000 tons of pollen are blown from the trees each year.””

— Richard M. Ketchum