AP BIOLOGY

Detailed explanation-1: -All conifers are pollinated by wind. Pollen may be produced in enormous quantities, particularly by species of true pine (Pinus), which can blanket the surface of nearby lakes and ponds with a yellow scum of pollen (the pollen can cause allergies in humans).

Detailed explanation-2: -Wind-pollinated plants don’t normally have flowers, but when they do they are small, don’t have perfumes or nectar, produce large amounts of light pollen, have stamens and stigmas exposed to air currents to either catch or distribute pollen and don’t normally have flower petals.

Detailed explanation-3: -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.

Detailed explanation-4: -One mechanism by which conifers promote cross-pollination is by increasing the distance their pollen grains travel. Each pollen grain is attached to two or three air-filled sacs, or sacci, which develop from the outer layer of the pollen wall.