Pollen tube through wind, water or pollinators. The last step before fertilization is the growth of the pollen tube to transfer non-motile sperm to the protected egg. Pollen tubes are unique to plants and their structure had evolved over plant history. The pollen tube formation is complex and the mechanism is not fully understood, but is of great interest to scientists. Pollen is produced by the stamen, the male reproductive organ of the flower. Each pollen grain contains a vegetative cell, and a generative cell that divides to form two sperm cells. The pollen is delivered by the opening of anthers for
Bee pollen in the chambers of honeybee hives, and sometimes in wood and mud created by female ground-nesting bees, such as the leafcutting bee. With the leafcutting bee, when the pollen ball is complete, a single female lays an egg on top of the pollen ball, and seals the brood cell. It differs from field gathered pollen as honey bee secretions induce a fermentation process, where biochemical transformations break down the walls of flower pollen grains and render the nutrients more readily available. Forager bees that gather pollen do not eat it themselves, since they stop producing the proteolytic enzymes necessary to