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. They are very important ecologically and provide many economically important products, such as lumber and paper. The largest of all organisms, the giant sequoias belong to this group. Division Cycadophyta - cycads Cycads have pinnately compound leaves and resemble large ferns or small palms.