Figure 28.4 Pollination Is a Hallmark of the Seed Plants In most seed plants, a pollen tube grows from the pollen grain to the female gametophyte, where sperm are released and fertilize the egg within the ovule. Once fertilization takes place, the ovule can develop into a seed (see Figure 28.5). (A) Scanning electron micrograph of a pollen tube growing in the flower of an angiosperm, the prairie gentian. (B) The process of pollination is diagrammed for a generalized angiosperm flower.