Gymnosperms Have Naked Seeds

Gymnosperms Have Naked Seeds

There are four divisions of gymnosperms (seed plants that bear naked seeds): the familiar conifers and the little-known cycads, ginkgo, and gnetophytes. In conifers, pollen (male) and seed (fe- male) cones are produced by the sporophyte plant. On the underside of a pollen cone scale, there are two microsporangia that produce microspores; each becomes a microgametophyte, or pollen grain. On the upper surface of a seed cone scale, there are two ovules, where meiosis produces one megaspore that develops into the megagametophyte. After windblown pollination, the pollen grain develops a tube through which sperm reach the egg. After fertiliza- tion, the ovule matures to be the seed.