The scalelike leaves are arranged in whorls around the hollow, photosynthetic stem. Spores are produced inside cone-shaped clusters of leaves at the shoot tip. Sori are clusters of sporangia that release spores that develop into small heart-shaped gametophytes. They produce microspores which give rise to pollen grains which serve as carriers of the sperm to the eggs. They also produce megaspores which develop within the ovules which will eventually produce seeds when the sperm fertilizes the egg.
Gymnosperms have water-conserving traits, including thick cuticles.
Pollination is the arrival of a pollen grain on the female reproductive parts, after which a pollen tube grows toward the egg. Fertilization, which is delayed for up to a year, results in a zygote that develops into an embryo within the conifer seed. Gymnosperm Diversity A. Conifers are woody trees and shrubs that produce needlelike leaves and bear seeds exposed on cone scales. Most species have coevolved with pollinators attracted to the pollen and nectar. This group has dominated the land for 100 million years, living a very diverse habitats.