The pollen tube is the tube through which sperm from the pollen reaches the egg cell, and fertilises the plant to form seeds.
The pollen tube of most seed plants acts as a passageway. It transports sperm cells from the pollen grain, from the stigma (in flowering plants) to the ovules at the base of the pistil. Like ferns, other basal land plants, and many algae, some gymnosperms have flagellate sperm, which swim through a watery fluid to fertilize the egg cells.