Each seed contains an embryo, nutritive tissue, and a seed coat, which comes from the integument. Gametophytes are not free-living, they derive their nutrition from the parent sporophyte. Gymnosperms Gymnosperm seeds are naked - there are no flowers or fruit. Pollen grains must be carried directly to micropyle of the ovule. Sperm travel through megasporangium in the pollen tube until they reach the archegonia, where they fertilize the eggs.
Gymnosperms comprise four divisions.
Only the conifers are ecologically or economically important. This is the largest and most familiar of the gymnosperms, and includes trees such as pine, spruce, bald cypress, and the giant redwoods. All conifers are woody, having secondary growth similar to woody angiosperms. Ovules are borne on ovuliferous scales in female cones. Conifers are the dominant plants in colder forests of the temperate regions, and are thus prominent in larger regions of the world.