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Umkomasiales
Corystosperms are a group of extinct seed plants (often referred to as "seed ferns") belonging to the family Corystospermaceae (also called Umkomasiaceae) assigned to the order Corystospermales or Umkomasiales. They were first described based on fossils collected by Hamshaw Thomas from the Burnera Waterfall locality near the Umkomaas River of South Africa. Corystosperms are typified by a group of plants that bore forked ''Dicroidium'' leaves, ''Umkomasia'' cupulate ovulate structures and ''Pteruchus'' pollen organs, which grew as trees that were widespread over Gondwana during the Middle and Late Triassic. Other fossil Mesozoic seed plants with similar leaf and/or reproductive structures have also sometimes been included within the "corystosperm" concept ''sensu lato'', such as the "doyleoids" from the Early Cretaceous of North America and Asia. A potential corystosperm ''sensu lato'', the leaf genus ''Komlopteris'', is known from the Eocene of Tasmania, around 53-50 million years ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seed Ferns
Pteridospermatophyta, also called pteridosperms or seed ferns, are a polyphyletic grouping of extinct Spermatophyte, seed-producing plants. The earliest fossil evidence for plants of this type are the Lyginopteridales, lyginopterids of late Devonian age. They flourished particularly during the Carboniferous and Permian periods. Pteridosperms declined during the Mesozoic Era and had mostly disappeared by the end of the Cretaceous Period, though ''Komlopteris'' seem to have survived into Eocene times, based on fossil finds in Tasmania. With regard to the enduring utility of this division (botany), division, many palaeobotanists still use the pteridosperm grouping in an informal sense to refer to the seed plants that are not angiosperms, coniferoids (conifers or cordaites), Ginkgoaceae, ginkgophytes (ginkgos or czekanowskiales), cycadophytes (cycads or Bennettitales, bennettites), or gnetophytes. This is particularly useful for extinct seed plant groups whose systematic relationship ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicroidium
''Dicroidium'' is an extinct genus of fork-leaved seed plants. It is the archetypal genus of the corystosperms, an extinct group of seed plants, often called " seed ferns", assigned to the order Corystospermales or Umkomasiales. Species of ''Dicroidium,'' which grew as large trees, were widely distributed and dominant over Gondwana during the Triassic (). Their fossils are known from South Africa, the Arabian Peninsula, Australia, New Zealand, South America, Madagascar, the Indian subcontinent and Antarctica. Description Within the form genus classification system used in paleobotany, the genus ''Dicroidium'' refers specifically to the leaves. Some authors have suggested dividing ''Dicroidium'' up into several genera, including ''Dicroidiopsis, Diplasiophyllum, Zuberia'', ''Xylopteris'', ''Johnstonia'' and ''Tetraptilon,'' but this is rejected by other authors. The leaves of ''Dicroidium'' bifurcate (fork) at their base, which is characteristic of all species. The leaves are h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seed Plant
A seed plant or spermatophyte (; New Latin ''spermat-'' and Greek ' (phytón), plant), also known as a phanerogam (taxon Phanerogamae) or a phaenogam (taxon Phaenogamae), is any plant that produces seeds. It is a category of embryophyte (i.e. land plant) that includes most of the familiar land plants, including the flowering plants and the gymnosperms, but not ferns, mosses, or algae. The term ''phanerogam'' or ''phanerogamae'' is derived from the Greek (), meaning "visible", in contrast to the term "cryptogam" or " cryptogamae" (, and (), 'to marry'). These terms distinguish those plants with hidden sexual organs (cryptogamae) from those with visible ones (phanerogamae). Description The extant spermatophytes form five divisions, the first four of which are classified as gymnosperms, plants that have unenclosed, "naked seeds": * Cycadophyta, the cycads, a subtropical and tropical group of plants, * Ginkgophyta, which includes a single living species of tree in the genus '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
