THE SEED PLANT A seed is a plant embryo and a food supply surrounded by a protective coat 1.Gymnosperm 2.Angiosperm Flowering Plants Non- Flowering Plants
The Gymnosperm gymno = naked sperm = seed angeion = case,capsule Any plant that produce seeds but does not form flowers is classified as a Gymnosperm.
Gymnosperms are vascular plants with true roots, stems and leaves. Most of them are trees or shrubs that live many years.
In gymnosperm, seeds develop without a protective wall. The seed of many gymnosperm are exposed to the air.They are on the surface of a cone scale. So gymnosperm are open seeded plant
There are now about 700 living species of gymnosperm.These are Conifers : Coniferophyta Cycads : Cycadophyta Ginkgoes ; Ginkgophyta
Coniferophyta : Conifers: Includes pine, spruce, yew, juniper, and other evergreens. Many have cones. About 600 species.
The largest group of gymnosperm is the conifers. The word conifer means “cone-bearing” Cones are structure that contain the seeds of the plant. Conifers are woody plant that live in areas of the world that are neither too hot nor too cold.
Most conifers such as pine, cedars, and hemlocks, are called evergreen because they appear to keep their leaves all year. The leaves or needles may remain for 2 to 12 years. Two exceptions are the larch and the bald cypress.lose their needles every fall.
Familiar trees such as pines, spruce, firs, and sequoias are conifers. They produce woody, seed-bearing structures called cones. The yew and juniper, produce seeds in cones that resemble berries.
Figure : Parts of a pine seed. Which part of the seed can grow into a pine tree?
Most conifers are trees, but some species of yews and junipers are shrubs. Conifers grow larger and older than any other trees. One of the largest is a redwood in California, 100 meters tall and 10 meters wide.
Conifers produce male and female cones on the same tree. The male cones contain pollen and the female cones contain ovules. The pollen is carried to the female cones by wind.
After the pollen and the ovule join, a seed develops. As the seed matures, part of the cone dries up and release the seeds. When a seed falls to the ground, the seed may develop into a new conifer.
Cycadophyta The Cycad
Cycadophyta : Palm-like plants called Cycads.About 100 species These tropical trees grow as tall as 18 meters. Cycads have large leaves.Like conifers, cycads have cones. But cycad trees are either male or female and the cones are located in the center of the leaves.
Ginkgophyta The Ginkgo
Figure : Left : A ginkgo tree has broad, fan-shaped leaves. Right :Zamia is a cycad
Ginkgophyta ; Ginkgoes: An ancient type of tree. Only one species survives They have fan-shaped leaves and can grow as tall as 30 meters
Like cycads,male and female cones are found on separate trees. After male and female sex cells join, yellowish seeds form.