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Trimerophyte
Trimerophytopsida (or Trimeropsida) is a class of early vascular plants from the Devonian, informally called trimerophytes. It contains genera such as ''Psilophyton''. This group is probably paraphyletic, and is believed to be the ancestral group from which both the ferns and seed plants evolved. Different authors have treated the group at different taxonomic ranks using the names Trimerophyta, Trimerophytophyta, Trimerophytina, Trimerophytophytina and Trimerophytales. Taxonomy At first most of the early land plants other than the bryophytes (i.e. the polysporangiophytes) were placed in a single class Psilophyta, established in 1917 by Kidston and Lang. As additional fossils were discovered and described, it became apparent that the Psilophyta were not a homogeneous group of plants. In 1968 Banks first proposed splitting this taxon into three groups, which he put at the rank of subdivision; he clarified his proposal in 1975. One of the three groups was the Trimerophytina. The subd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polysporangiophyte
Polysporangiophytes, also called polysporangiates or formally Polysporangiophyta, are plants in which the spore-bearing generation (sporophyte) has branching stems (axes) that bear sporangia. The name literally means 'many sporangia plant'. The clade includes all land plants (embryophytes) except for the bryophytes (liverworts, mosses and hornworts) whose sporophytes are normally unbranched, even if a few exceptional cases occur. While the definition is independent of the presence of vascular tissue, all living polysporangiophytes also have vascular tissue, i.e., are vascular plants or tracheophytes. Extinct polysporangiophytes are known that have no vascular tissue and so are not tracheophytes. Early polysporangiophytes History of discovery Paleobotanists distinguish between micro- and megafossils. Microfossils are primarily spores, either single or in groups. Megafossils are preserved parts of plants large enough to show structure, such as stem cross-sections or branching patte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psilophyton
''Psilophyton'' is a genus (biology), genus of extinct vascular plants. Described in 1859, it was one of the first fossil plants to be found which was of Devonian age (about ). Specimens have been found in northern Maine, USA; Gaspé Bay, Quebec and New Brunswick, Canada; the Czech Republic; and Yunnan, China. Plants lacked leaves or true roots; spore-forming organs or Sporangium, sporangia were borne on the ends of branched clusters. It is significantly more complex than some other plants of comparable age (e.g. ''Rhynia'') and is thought to be part of the group from within which the modern ferns and seed plants evolved. Description Almost all the species of ''Psilophyton'' have been found in rocks of Emsian age (around ). One exception is ''P. krauselii'', from the Czech Republic, which is younger, being from the upper part of the Middle Devonian (around ). ''Psilophyton dawsonii'' is the best-known species. Compressed and mineralized specimens have been found in sever ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian Plants
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. The arthropod groups of myriapods, arachnids and hexapods also became well-established early in this period, after starting their expansion to land at least from the Ordovician period. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fishes. The placoderms began dominating al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euphyllophyta
The euphyllophytes are a clade of plants within the tracheophytes (the vascular plants). The group may be treated as an unranked clade, a division under the name Euphyllophyta or a subdivision under the name Euphyllophytina. The euphyllophytes are characterized by the possession of true leaves ("megaphylls"), and comprise one of two major lineages of extant vascular plants. As shown in the cladogram below, the euphyllophytes have a sister relationship to the lycopodiophytes or lycopsids. Unlike the lycopodiophytes, which consist of relatively few presently living or extant taxa, the euphyllophytes comprise the vast majority of vascular plant lineages that have evolved since both groups shared a common ancestor more than 400 million years ago. The euphyllophytes consist of two lineages, the spermatophytes A spermatophyte (; ), also known as phanerogam (taxon Phanerogamae) or phaenogam (taxon Phaenogamae), is any plant that produces seeds, hence the alternative name seed plant. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hostinella
''Hostinella'' is a form genus, used for bare dichotomously branching stems (axes) which have not been found in association with spore-forming organs or sporangia and so cannot be assigned to a more precise genus or species. Specimens assigned to this genus have been found in Bathurst Island, Canada, in the Bertie Formation of Upper Silurian age (around ), where the stems are approximately 1.2 mm in diameter; and in Lower Devonian Senni beds (from around ) where the axes have a straited external appearance and contain xylem with tracheids (diameter: 40 µm). It is known to co-occur with ''Krithodeophyton ''Krithodeophyton'' is a genus of lower Devonian plant with branching axes. It is considered to be a barinophyte. Phylogeny The phylogenetic position of the barinophytes remains disputed. Kenrick and Crane in 1997 called the group the Barinophy ...''. References Silurian plants Early Devonian plants Prehistoric plant genera Silurian first appearances E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type (biology)
In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes the defining features of that particular taxon. In older usage (pre-1900 in botany), a type was a taxon rather than a specimen. A taxon is a scientifically named grouping of organisms with other like organisms, a set that includes some organisms and excludes others, based on a detailed published description (for example a species description) and on the provision of type material, which is usually available to scientists for examination in a major museum research collection, or similar institution. Type specimen According to a precise set of rules laid down in the International Code of Zoological Nomenclature (ICZN) and the International Code of Nomenclature for algae, fungi, and plants (ICN), the scientific name of every taxon is almost al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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