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-Definition.!* : gymnospern are group of vascular -cycads.!* was much more extensive than at -conifers.!* :appeared first toward the end of plants. present. In fact, gymnosperms were dominant in the Late Carboniferous epoch [320 to 286 the Mesozoic. Paleozoic seed ferns resembled million years ago]. Some of the earliest -Discovery.!* : In 1825 the scotish botanist Robert some progymnosperms in that they were small conifers [class Cordaitopsida] were trees Brown trees with fernlike leaves ,There has been one with long, strap-shaped leaves. Trunks were report of a pollination droplet in a Carboniferous similar to those of extant conifers, with pteridosperm ovule and a report of a pollen tube dense, compact wood; small thick-walled -Information.about.gynospern.!* : the seeds of many emerging from a pollen grain in the micropyle of a tracheids; gymnospern are borne in cons and are not visible , this seed-fern ovule, suggesting that transport of the Reproductive axes were slender, bearing are not like fruits. Some of the division of gymnospern sperm through a pollen tube was in existence as narrow bracts in the axils of which were are not closete releated to others, having been far back as the Paleozoic. It is generally conceded small, budlike shoots with helically arranged distintict groups for hundres million of years. that from the pteridosperms arose members of the scales. By the late Paleozoic there came into division Cycadophyta. The first cycads appeared in existence another group of extinct conifers, the the Voltziales , distinguished gymnospern from other major group of seed plants. General.features.!* Permian period ,Other Permian and narrow vascular rays. Reproductive axes were megasporophylls, from China, are more like those generally homologous with those of the -Diversity.size.and.structure.!*:Among the gymnosp- of Cycas. Cycad remains, especially leaves, are Cordaitales, but they were more compact. erms are plants with stems that may barely project abundant in Mesozoic rocks. For this reason Reproductive organs of seed ferns were above the ground and others that develop into the paleobotanists often refer to the Mesozoic era as borne upon the foliage; single ovules and largest of trees. Cycads resemble palm trees, with the "age of cycads." The earliest well-known seeds were borne in place of pinnae, while fleshy cycads stems, male organs often occurred as compound sometimes branched, with leaves not borne close pollen organs composed of partially or wholly -distribution.and.abundance.!* : gymnosperms have together, unlike the situation in extant cycads in united been gradually displaced by the more recently evolved which leaves are densely crowded at the apex of gymnosperms, the ovule consisted of one angiosperms, they are still successful in many parts of the plant. megasporangium .It is generally conceded stems and leathery, feat herlike leaves. appear to have had slender the world and occupy large areas of the Earth's surface, microsporangia. As in other that from the pteridosperms arose members Gymnosperms that occupy areas of the -exant cycads : Extant cycads are now limited in world with severe climatic conditions are adapted to geographic distribution to the warmer parts of the conserving water; leaves are covered with a heavy, earth. waxy cuticle, and pores. Mesozoic was another group of gymnosperms, the Coexisting with the cycads during the cycadeoids,Although they are superficially similar in habit to the cycads. of the division Cycadophyta.