PLANT TRANSITION TO DRY LAND. “Plants faced precisely the same problem: that of the pteridophytic life cycle with its free-living gametophytes and swimming sperm in need of freestanding water, being dragged from their supportive environment by the increasingly complex sporophytic adaptations to life on land.”
https://academic.oup.com/bioscience/article/65/6/626/304981/Seeds-and-Fruits-Underwriting-the-Diversity-of