: After a pollen grain lands on a compatible receptive surface (the stigma in flowering plants or the micropyle in gymnosperms), it germinates. A tube emerges and grows through the maternal tissue.
: The evolution of the pollen tube allowed plants to reproduce without needing external water for sperm to swim through, a major leap in the colonization of land. Specialized Structures in Gymnosperms mature orgasm tubes
: In more primitive seed plants like cycads, the mature pollen tube is haustorial—it grows into the nucellus tissue to absorb nutrients. Eventually, it releases motile, flagellated sperm cells into a "fertilization chamber" near the egg. : After a pollen grain lands on a
The development of a mature pollen tube is a critical stage in the life cycle of seed plants. It acts as a conduit, delivering male gametes (sperm) to the female gametophyte to achieve fertilization. Specialized Structures in Gymnosperms : In more primitive
: The active transport of nutrients and the vegetative nucleus toward the growing front.