Gymnosperms

=**Gymnosperms**=

Gymnospermae is a group of seed-bearing plants with ovules on scales. Unlike angiosperms, gymnosperms bear their seeds directly on the surfaces of cones rather than within a layer of tissue that protects the seed. Gymnosperms can live relatively anywhere, including the dry and cold climates where seedless plants cannot survive. There are four main types of gymnosperms: cycads, conifers, gnetophytes, and gingkoes.
 * General:**

//Conifers//, including pines and spruces, are the most common type of gymnosperms with over 500 different species. Some can live for thousands of years and grow to be more than 100 meters tall. Some conifers require flaming hot fire to germinate so the cone will bursts open exposing the seeds. Although, new fresh needles gradually replace old needles, some conifers can keep their needles for 2-14 years. These fallen pine needles cause soil to be acidic thereby determining the surrounding flora. The low surface area of needles prevents water loss because the water cannot evaporate as easily. The needles also have a waxy layer to help retain water.

//Cycads// are palm-like plants that reproduce with very large cones. They live in tropical and subtropical environments and have been around since the dinosaurs.

//Ginkgoes// are another type of gymnosperm that were common to the age of the dinosaurs. They are also highly resistant to air pollution.


 * Divisions of Gymnosperms:**



Gymnosperm embryos are protected in seeds. Cones are sporophyte structures in which gametophytes grow and mature. Pollen grains contain entire male gametophytes, which are carried by wind, insects, and other critters to the female reproductive structure. Unlike other plants, gymnosperms do no require water for fertilization of gametes. The Gymnosperm lifecycle alternates between gametophyte and sporophyte stages.
 * Reproduction:**