Pollen cell. In flowering plants the vegetative tube cell produces the pollen tube, and the generative cell divides to form the two sperm cells. Pollen is produced in the microsporangia in the male cone of a conifer or other gymnosperm or in the anthers of an angiosperm flower. Pollen grains come in a wide variety of shapes, sizes, and surface markings characteristic of the species (see electron micrograph, right). Pollen grains of pines, firs, and spruces are winged. The smallest pollen grain, that of the forget-me-not ("Myosotis" spp.), is around 6 µm (0.006 mm) in diameter. Wind-borne pollen grains can be
Pollen drift the distance it can travel and via what methods, and how to plant their fields to avoid unwanted cross-pollination. Corn pollen is particularly prone to pollen drift. Corn plants release their pollen for around a week, and an entire field may take up to two weeks to completely release its pollen; pollen release usually shows a spike two to three days after half the plants have released their pollen. Each individual plant can produce 4 to 5 million individual pollen grains. Its pollen is among the largest particles that can be found in the air, and is spherical in its