pollens

Pollen is the fine powder produced by the male structures of seed plants. In angiosperms, pollen is produced in the anthers of flowers; in gymnosperms, in the microsporangia of cones. Each pollen grain contains the male gametophyte and is adapted for transfer to a female reproductive organ, enabling fertilization if it reaches a compatible stigma or ovule.

Pollen grains have a resistant outer wall called the exine, made largely of sporopollenin, and an inner wall called the intine. The grain contains the vegetative cell and, in many species, a generative cell that divides to form sperm cells. Upon landing on a compatible stigma, the pollen grain germinates and grows a pollen tube toward the ovule, delivering sperm for fertilization.

Dispersal occurs through wind (anemophily), water, or animal pollinators (entomophily, zoophily). Wind-pollinated species tend to produce large quantities of small, smooth pollen, while animal-pollinated species have stickier or sculptured grains that attach to pollinators. Pollen viability and germination depend on species, climate, and storage; pollen remains identifiable in sediments for palynology studies of past environments.

For humans, pollen is a common allergen and a factor in seasonal illnesses. Pollen counts are used in forecasts and public health advisories. Ecologically and economically, pollen-mediated fertilization underpins many crops and wild plant communities, making pollination a critical process in food production and biodiversity.