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Taxaceae
Taxaceae (), commonly called the yew family, is a coniferous family which includes six extant and two extinct genera, and about 30 species of plants, or in older interpretations three genera and 7 to 12 species. Description They are many-branched, small trees and shrubs. The leaves are evergreen, spirally arranged, often twisted at the base to appear 2-ranked. They are linear to lanceolate, and have pale green or white stomatal bands on the undersides. The plants are dioecious, or rarely monoecious. The catkin like male cones are long, and shed pollen in the early spring. They are sometimes externally only slightly differentiated from the branches. The fertile bracts have 2-8 pollen sacs. The female 'cones' are highly reduced. Only the upper or uppermost bracts are fertile and bear one or rarely two seeds. The ovule usually exceeds the scale, although ovules are sometimes rarely enclosed by it. They may be found on the ends of branches or on the branches. They may grow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conifer
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extant conifers are perennial woody plants with secondary growth. The great majority are trees, though a few are shrubs. Examples include cedars, Douglas-firs, cypresses, firs, junipers, kauri, larches, pines, hemlocks, redwoods, spruces, and yews.Campbell, Reece, "Phylum Coniferophyta". Biology. 7th. 2005. Print. P. 595 As of 1998, the division Pinophyta was estimated to contain eight families, 68 genera, and 629 living species. Although the total number of species is relatively small, conifers are ecologically important. They are the dominant plants over large areas of land, most notably the taiga of the Northern Hemisphere, but also in similar cool climates in mountains further south. Boreal conifers have many wintertime ada ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pinales
The order Pinales in the division Pinophyta, class Pinopsida, comprises all the extant conifers. The distinguishing characteristic is the reproductive structure known as a cone produced by all Pinales. All of the extant conifers, such as cedar, celery-pine, cypress, fir, juniper, larch, pine, redwood, spruce, yew and '' Araucaria araucana'' ("Monkey tail tree" or "Monkey puzzle tree") are included here. Some fossil conifers, however, belong to other distinct orders within the division Pinophyta. Multiple molecular studies indicate this order being paraphyletic with respect to Gnetales, with studies recovering Gnetales as either a sister group to Pinaceae or being more derived than Pinaceae but sister to the rest of the group. Taxonomy History Brown (1825) first discerned that there were two groups of seed plants, distinguished by the form of seed development, based on whether the ovules were exposed, receiving pollen directly, or enclosed, which do not. Shortly afterwa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torreya
''Torreya'' is a genus of conifers comprising six or seven species placed in the family Taxaceae, though sometimes formerly placed in Cephalotaxaceae. Four species are native to eastern Asia; the other two are native to North America. They are small to medium-sized evergreen trees reaching 5–20 m, rarely 25 m, tall. Common names include nutmeg yew. The genus is one example of the Arcto-Tertiary Geoflora in paleoecology. The pattern of highly disjunct distribution of geographic ranges of the species within such a genus spans temperate plant zones of continents in the Northern Hemisphere. This geographic pattern is attributed to genus origins in much warmer times of the Tertiary Period, when zones of temperate climate were found in poleward latitudes whereby land connections facilitated range expansions and migrations of plants between Asia and North America and sometimes between Europe and North America. The leaves are spirally arranged on the shoots, but twisted at the base ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxus
''Taxus'' is a genus of coniferous trees or shrubs known as yews in the family Taxaceae. They are relatively slow-growing and can be very long-lived, and reach heights of , with trunk girth averaging . They have reddish bark, lanceolate, flat, dark-green leaves long and broad, arranged spirally on the stem, but with the leaf bases twisted to align the leaves in two flat rows either side of the stem. The oldest known fossil species are from the Early Cretaceous. Morphology The seed cones are highly modified, each cone containing a single seed long partly surrounded by a modified scale which develops into a soft, bright red berry-like structure called an aril, long and wide and open at the end. The arils are mature 6–9 months after pollination, and with the seed contained are eaten by thrushes, waxwings and other birds, which disperse the hard seeds undamaged in their droppings; maturation of the arils is spread over 2–3 months, increasing the chances of successful ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Austrotaxus
''Austrotaxus spicata'', the New Caledonia yew or southern yew, is a species of yew, the sole species in the genus ''Austrotaxus''. It is related to the other yews in the genera ''Taxus'' and '' Pseudotaxus''. It is endemic to New Caledonia, occurring in the central and northern parts of the island at 300-1,350 m altitude. It is a dioecious coniferous shrub or small tree, reaching 5–20 m (rarely 25 m) tall with reddish bark. The leaves are lanceolate, flat, 8–12 cm long (up to 17 cm on young plants) and 4 mm broad, dark green above, with two paler green stomatal bands below; they are arranged spirally on the stem. The seed cones are drupe-like, 20–25 mm long, with a fleshy aril almost completely surrounding the single seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalotaxus
''Cephalotaxus'', commonly called plum yew or cowtail pine, is a genus of conifers comprising 11 species, treated in either the Cephalotaxaceae, or in the Taxaceae when that family is considered in a broad sense. The genus is endemic to eastern Asia, though fossil evidence shows it had a wider Northern Hemisphere distribution in the past. The species are evergreen shrubs and small trees reaching (rarely to ) tall. Taxonomy Molecular studies place ''Cephalotaxus'' as the most basal member of the Taxaceae, having a very ancient divergence from them during the late Triassic. Description The leaves are spirally arranged on the shoots, but twisted at the base to lie in two flat ranks (except on erect leading shoots); they are linear, long and broad, soft in texture, with a blunt tip; this helps distinguish them from the related genus ''Torreya'', which has spine-tipped leaves. The species can be either monoecious or dioecious; when monoecious, the male and female cones ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxales
The plant order Taxales was until recently treated as a distinct order in the division Pinophyta, class Pinopsida, and included only those species in the family Taxaceae, known commonly as yews. Under this interpretation, all other conifers were classified separately in the order Pinales. Recent genetic and micromorphological studies, however, have shown the Taxaceae are closely related to the other conifers, particularly so to the family Cephalotaxaceae. The order Taxales is therefore no longer recognised as distinct, and the family Taxaceae is now included in the order Cupressales. See Pinophyta
Conifers are a group of cone-bearing seed plants, a subset of gymnosperm ...
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Pseudotaxus
''Pseudotaxus chienii'', the whiteberry yewThomas, P. & Yang, Y. 2013''Pseudotaxus chienii''.The IUCN Red List of Threatened Species. Version 2015.2. Downloaded on 04 September 2015. (), is a species of plant in the yew family, Taxaceae. It is the sole species in the genus ''Pseudotaxus'', but closely related to the other yews in the genus ''Taxus''. It is endemic to southern China, occurring in northern Guangdong, northern Guangxi, Hunan, Southwest Jiangxi and southern Zhejiang. Like other yews, it is a small coniferous shrub or small tree, reaching 2–5 m tall with reddish bark. The leaves are lanceolate, flat, 1–2.6 cm long and 2–3 mm broad, dark green above, with two white stomatal bands below; they are arranged spirally on the stem, but with the leaf bases twisted to align the leaves in two flat rows either side of the stem. The conspicuous white stomatal bands on the harder, stiffer (less soft) leaves readily distinguish it from the yews in the genus '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined. By the beginning of the Jurassi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxine
Taxine alkaloids, which are often named under the collective title of taxines, are the toxic chemicals that can be isolated from the yew tree. The amount of taxine alkaloids depends on the species of yew, with ''Taxus baccata'' and '' Taxus cuspidata'' containing the most. The major taxine alkaloids are taxine A and taxine B although there are at least 10 different alkaloids. Until 1956, it was believed that all the taxine alkaloids were one single compound named taxine. The taxine alkaloids are cardiotoxins with taxine B being the most active. Taxine alkaloids have no medical uses but Paclitaxel and other taxanes that can be isolated from yews have been used as chemotherapy drugs. Provenance Taxine can be found in Taxus species: '' Taxus cuspidata, T. baccata'' (English yew), '' Taxus x media, Taxus canadensis, Taxus floridana,'' and '' Taxus brevifolia'' (Pacific or western yew). All of these species contain taxine in every part of the plant except in the aril, the fles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conifer Cone
A conifer cone (in formal botanical usage: strobilus, plural strobili) is a seed-bearing organ on gymnosperm plants. It is usually woody, ovoid to globular, including scales and bracts arranged around a central axis, especially in conifers and cycads. The cone of Pinophyta (conifer clade) contains the reproductive structures. The woody cone is the female cone, which produces seeds. The male cone, which produces pollen, is usually herbaceous and much less conspicuous even at full maturity. The name "cone" derives from Greek ''konos'' (pine cone), which also gave name to the geometric cone. The individual plates of a cone are known as ''scales''. The ''umbo'' of a conifer cone refers to the first year's growth of a seed scale on the cone, showing up as a protuberance at the end of the two-year-old scale. The male cone (microstrobilus or pollen cone) is structurally similar across all conifers, differing only in small ways (mostly in scale arrangement) from species to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sommerxylon
''Sommerxylon'' is a genus described from petrified trunks of Gymnosperms that lived in the Triassic, found in the Caturrita Formation on Linha São Luiz in the municipality of Faxinal do Soturno in the region of Paleorrota. It is named in honor of Dr. ''Margot Guerra Sommer''. Description Pith composed of parenchyma cells and sclerenchyma cells, primary xylem is endarch, secondary xylem with points with halos that dominate, thick radial walls of tracheids, absence of resin canals and axial parenchyma, indicate its relationship to the family Taxaceae Taxaceae (), commonly called the yew family, is a coniferous family which includes six extant and two extinct genera, and about 30 species of plants, or in older interpretations three genera and 7 to 12 species. Description They are many-bran .... References Kaokoxylon zalesskyi (Sahni) Maheshwari en los niveles superiores de la Secuencia Santa MariaO complexo Dadoxylon-Araucarioxylon, Carbonífero e PermianoTécnica de co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
