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Adoketophyton Parvulum Strobilus
''Adoketophyton'' is a genus of extinct vascular plants of the Early Devonian (Pragian stage, around ). The plant was first described in 1977 based on fossil specimens from the Posongchong Formation, Wenshan district, Yunnan, China. These were originally named ''Zosterophyllum subverticillatum''; later the species was transferred to a new genus as ''Adoketophyton subverticillatum''. One cladistic analysis suggested that it is a lycophyte, related to the zosterophylls. Other researchers regard its placement within the vascular plants as uncertain. Description Like other Early Devonian plants, the sporophyte of ''Adoketophyton'' consisted of leafless stems (axes), approximately 1 to 2.5 mm in diameter. These branched equally or unequally (pseudomonopodially). Its vascular tissue was relatively simple, consisting of a central ( centrarch) cylinder of primary xylem with G-type tracheids. Fossils suggest that stems which did not bear sporangia initially had coiled (circinnate) t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tracheid
A tracheid is a long and tapered lignified cell in the xylem of vascular plants. It is a type of conductive cell called a tracheary element. Angiosperms use another type of tracheary element, called vessel elements, to transport water through the xylem. The main functions of tracheid cells are to transport water and inorganic salts, and to provide structural support for trees. There are often pits on the cell walls of tracheids, which allows for water flow between cells. Tracheids are dead at functional maturity and do not have a protoplast. The wood (softwood) of gymnosperms such as pines and other conifers is mainly composed of tracheids. Tracheids are also the main conductive cells in the primary xylem of ferns. The tracheid was first named after the German botanist Carl Gustav Sanio in 1863, from the German ''Tracheide''. Evolution Tracheids were the main conductive cells found in early vascular plants. In the first 140-150 million years of vascular plant evolution, tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Devonian Plants
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Early may refer to: History * The beginning or oldest part of a defined historical period, as opposed to middle or late periods, e.g.: ** Early Christianity ** Early modern Europe Places in the United States * Early, Iowa * Early, Texas * Early Branch, a stream in Missouri * Early County, Georgia Other uses * ''Early'' (Scritti Politti album), 2005 * ''Early'' (A Certain Ratio album), 2002 * Early (name) * Early effect, an effect in transistor physics * Early Records, a record label * the early part of the morning See also * Earley (other) Earley is a town in England. Earley may also refer to: * Earley (surname), a list of people with the surname Earley * Earley (given name), a variant of the given name Earlene * Earley Lake, a lake in Minnesota *Earley parser, an algorithm *Earley ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lycopodiophyta
The lycophytes, when broadly circumscribed, are a vascular plant (tracheophyte) subgroup of the kingdom Plantae. They are sometimes placed in a division Lycopodiophyta or Lycophyta or in a subdivision Lycopodiophytina. They are one of the oldest lineages of extant (living) vascular plants; the group contains extinct plants that have been dated from the Silurian (ca. 425 million years ago). Lycophytes were some of the dominating plant species of the Carboniferous period, and included tree-like species, although extant lycophytes are relatively small plants. The scientific names and the informal English names used for this group of plants are ambiguous. For example, "Lycopodiophyta" and the shorter "Lycophyta" as well as the informal "lycophyte" may be used to include the extinct zosterophylls or to exclude them. Description Lycophytes reproduce by spores and have alternation of generations in which (like other vascular plants) the sporophyte generation is dominant. Some lycophyte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stem Group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. It is thus a way of defining a clade, a group consisting of a species and all its extant or extinct descendants. For example, Neornithes (birds) can be defined as a crown group, which includes the most recent common ancestor of all modern birds, and all of its extant or extinct descendants. The concept was developed by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms relative to their extinct relatives in his "Die Stammesgeschichte der Insekten", and the "crown" and "stem" group terminology was coined by R. P. S. Jefferies in 1979. Though formulated in the 1970s, the term was not commonly used until its reintroduction in 2000 by Graham Budd and Sören Jensen. Contents of the crown gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraphyletic
In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In contrast, a monophyletic group (a clade) includes a common ancestor and ''all'' of its descendants. The terms are commonly used in phylogenetics (a subfield of biology) and in the tree model of historical linguistics. Paraphyletic groups are identified by a combination of Synapomorphy and apomorphy, synapomorphies and symplesiomorphy, symplesiomorphies. If many subgroups are missing from the named group, it is said to be polyparaphyletic. The term was coined by Willi Hennig to apply to well-known taxa like Reptilia (reptiles) which, as commonly named and traditionally defined, is paraphyletic with respect to mammals and birds. Reptilia contains the last common ancestor of reptiles a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adoketophyton Parvulum Strobilus
''Adoketophyton'' is a genus of extinct vascular plants of the Early Devonian (Pragian stage, around ). The plant was first described in 1977 based on fossil specimens from the Posongchong Formation, Wenshan district, Yunnan, China. These were originally named ''Zosterophyllum subverticillatum''; later the species was transferred to a new genus as ''Adoketophyton subverticillatum''. One cladistic analysis suggested that it is a lycophyte, related to the zosterophylls. Other researchers regard its placement within the vascular plants as uncertain. Description Like other Early Devonian plants, the sporophyte of ''Adoketophyton'' consisted of leafless stems (axes), approximately 1 to 2.5 mm in diameter. These branched equally or unequally (pseudomonopodially). Its vascular tissue was relatively simple, consisting of a central ( centrarch) cylinder of primary xylem with G-type tracheids. Fossils suggest that stems which did not bear sporangia initially had coiled (circinnate) t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wheat
Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeological record suggests that wheat was first cultivated in the regions of the Fertile Crescent around 9600 BCE. Botanically, the wheat kernel is a type of fruit called a caryopsis. Wheat is grown on more land area than any other food crop (, 2014). World trade in wheat is greater than for all other crops combined. In 2020, world production of wheat was , making it the second most-produced cereal after maize. Since 1960, world production of wheat and other grain crops has tripled and is expected to grow further through the middle of the 21st century. Global demand for wheat is increasing due to the unique viscoelastic and adhesive properties of gluten proteins, which facilitate the production of processed foods, whose consumption is inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strobilus
A strobilus (plural: strobili) is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but some botanists restrict the use of the term cone to the woody seed strobili of conifers. Strobili are characterized by a central axis (anatomically a stem) surrounded by spirally arranged or decussate structures that may be modified leaves or modified stems. Leaves that bear sporangia are called ''sporophylls'', while sporangia-bearing stems are called '' sporangiophores''. Lycophytes Some members of both of the two modern classes of Lycopodiophyta (Lycopodiopsida and Isoetopsida) produce strobili. In all cases, the lateral organs of the strobilus are microphylls, bearing sporangia. In other lycophytes, ordinary foliage leaves can act as sporophylls, and there are no organized strobili. Diphasiastrum complanatum strobilus (01).jpeg, Strobili of ''Diphasiastrum'' Lycopodium saururus.JPG, St ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fern
A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except the lycopods, and differ from mosses and other bryophytes by being vascular, i.e., having specialized tissues that conduct water and nutrients and in having life cycles in which the branched sporophyte is the dominant phase. Ferns have complex leaves called megaphylls, that are more complex than the microphylls of clubmosses. Most ferns are leptosporangiate ferns. They produce coiled fiddleheads that uncoil and expand into fronds. The group includes about 10,560 known extant species. Ferns are defined here in the broad sense, being all of the Polypodiopsida, comprising both the leptosporangiate (Polypodiidae) and eusporangiate ferns, the latter group including horsetails, whisk ferns, marattioid ferns, and ophioglossoid ferns. Ferns first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sporangium
A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cycle. Sporangia can produce spores by mitosis, but in nearly all land plants and many fungi, sporangia are the site of meiosis and produce genetically distinct haploid spores. Fungi In some phyla of fungi, the sporangium plays a role in asexual reproduction, and may play an indirect role in sexual reproduction. The sporangium forms on the sporangiophore and contains haploid nuclei and cytoplasm. Spores are formed in the sporangiophore by encasing each haploid nucleus and cytoplasm in a tough outer membrane. During asexual reproduction, these spores are dispersed via wind and germinate into haploid hyphae. Although sexual reproduction in fungi varies between phyla, for some fungi the sporangium plays an indirect role in sexual reprod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylem
Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived from the Ancient Greek word (''xylon''), meaning "wood"; the best-known xylem tissue is wood, though it is found throughout a plant. The term was introduced by Carl Nägeli in 1858. Structure The most distinctive xylem cells are the long tracheary elements that transport water. Tracheids and vessel elements are distinguished by their shape; vessel elements are shorter, and are connected together into long tubes that are called ''vessels''. Xylem also contains two other type of cells: parenchyma and fibers. Xylem can be found: * in vascular bundles, present in non-woody plants and non-woody parts of woody plants * in secondary xylem, laid down by a meristem called the vascular cambium in woody plants * as part of a stelar arrangement n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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