Canada yew | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Gymnospermae |
Division: | Pinophyta |
Class: | Pinopsida |
Order: | Cupressales |
Family: | Taxaceae |
Genus: | Taxus |
Species: | T. canadensis |
Binomial name | |
Taxus canadensis | |
Natural range of T. canadensis | |
Synonyms [2] [3] | |
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Taxus canadensis, the Canada yew [2] or Canadian yew, is a conifer native to central and eastern North America, thriving in swampy woods, ravines, riverbanks and on lake shores. Locally called simply as "yew", this species is also referred to as American yew or ground-hemlock.
Most of its range is well north of the Ohio River. It is, however, found as a rare ice age relict in some coves of the Appalachian Mountains. The southernmost colonies are known from Ashe and Watauga Counties in North Carolina. [4]
It is usually a sprawling shrub, rarely exceeding 2.5 m tall. It sometimes forms strong upright central leaders, but these cannot be formed from spreading branches, only from the original leader of the seedling plant. The shrub has thin scaly brown bark. The leaves (needles) are lanceolate, flat, dark green, 1–2.5 cm (3⁄8–1 inch) long and 1–2.4 mm (0.039–0.094 inches) broad, [3] arranged in two flat rows either side of the branch.
The seed cones are highly modified, each cone containing a single seed partly surrounded by a modified scale which develops into a soft, bright red berry-like structure called an aril, open at the end. The seeds are eaten by thrushes, waxwings and other birds, which disperse the (highly toxic) [5] hard seeds undamaged in their droppings. The male cones are globose, 3 mm in diameter. It is a monoecious plant – one of the few in the genus.
All parts of Canadian yew, save the aril, are toxic; it is, however, thought to be of lower toxicity than T. baccata .[ citation needed ]
Native Americans in its native range used small quantities of yew leaf tea topically or internally for a variety of ailments – notably rheumatism. They are also been said to have used yew twigs in steam baths to help alleviate rheumatism. Again, the plant is quite toxic and modern herbalists prefer safer, more effective herbs. [ citation needed ]
Taxus canadensis is also being harvested in northern Ontario, Québec and Atlantic Canada as the plant is a source of the class of poisonous chemicals known as taxanes, which have been a focus for cancer research. [6] T. canadensis is much more abundant than the near-threatened Taxus brevifolia (Pacific yew), and the "greens" (new growth) can be harvested sustainably every five years, instead of stripping the bark and killing the plant.
The most abundant taxane in T. canadensis is 9-dihydro-13-acetylbaccatin III, which can be effectively converted to 10-deacetylbaccatin III, used in the production of paclitaxel. [7] Two additional taxanes have been identified from T. canadensis, including 7β,10β,13α-triacetoxy-5α-(3'-dimethylamino-3'-phenylpropanoyl)oxy-2α-hydroxy-2(3→20)abeotaxa-4(20),11-dien-9-one; and 2α,10β-diacetoxy-9α-hydroxy-5α-(3'-dimethylamino-3'-phenylpropanoyl)oxy-3,11-cyclotax-4(20)-en-13-one. [8]
Paclitaxel, sold under the brand name Taxol among others, is a chemotherapy medication used to treat ovarian cancer, esophageal cancer, breast cancer, lung cancer, Kaposi's sarcoma, cervical cancer, and pancreatic cancer. It is administered by intravenous injection. There is also an albumin-bound formulation.
Taxus is a genus of coniferous trees or shrubs known as yews in the family Taxaceae. Yews occur around the globe in temperate zones of the northern hemisphere, northernmost in Norway and southernmost in the South Celebes. Some populations exist in tropical highlands.
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.
Goldenseal, also called orangeroot or yellow puccoon, is a perennial herb in the buttercup family Ranunculaceae, native to North America. It may be distinguished by its thick, yellow knotted rootstock. The stem is purplish and hairy above ground and yellow below ground where it connects to the yellow rhizome. Goldenseal reproduces both clonally through the rhizome and sexually, with clonal division more frequent than asexual reproduction. It takes between 4 and 5 years for a plant to reach sexual maturity, i.e. the point at which it produces flowers. Plants in the first stage, when the seed erupts and cotyledons emerge, can remain in this state one or more years. The second vegetative stage occurs during years two and three and is characterized by the development of a single leaf and absence of a well developed stem. Finally, the third stage is reproductive, at which point flowering and fruiting occurs. This last stage takes between 4 and 5 years to develop.
An aril, also called an arillus, is a specialized outgrowth from a seed that partly or completely covers the seed. An arillode or false aril is sometimes distinguished: whereas an aril grows from the attachment point of the seed to the ovary, an arillode forms from a different point on the seed coat. The term "aril" is sometimes applied to any fleshy appendage of the seed in flowering plants, such as the mace of the nutmeg seed. Arils and arillodes are often edible enticements that encourage animals to transport the seed, thereby assisting in seed dispersal. Pseudarils are aril-like structures commonly found on the pyrenes of Burseraceae species that develop from the mesocarp of the ovary. The fleshy, edible pericarp splits neatly in two halves, then falling away or being eaten to reveal a brightly coloured pseudaril around the black seed.
Podocarpus macrophyllus is a conifer in the genus Podocarpus, family Podocarpaceae. It is the northernmost species of the genus, native to southern Japan and southern and eastern China. Common names in English include yew plum pine, Buddhist pine, fern pine and Japanese yew. Kusamaki (クサマキ) and inumaki (犬槇) are Japanese names for this tree. In China, it is known as luóhàn sōng (羅漢松), which literally means "arhat pine".
Sanguinaria canadensis, bloodroot, is a perennial, herbaceous flowering plant native to eastern North America. It is the only species in the genus Sanguinaria, included in the poppy family Papaveraceae, and is most closely related to Eomecon of eastern Asia.
Taxus baccata is a species of evergreen tree in the family Taxaceae, native to Western Europe, Central Europe and Southern Europe, as well as Northwest Africa, northern Iran, and Southwest Asia. It is the tree originally known as yew, though with other related trees becoming known, it may be referred to as common yew, European yew, or in North America English yew. It is a woodland tree in its native range, and is also grown as an ornamental tree, hedge or topiary. The plant is poisonous, with toxins that can be absorbed through inhalation, ingestion, and transpiration through the skin. Consuming any part of the tree, excluding the aril, can be deadly and the consumption of even a small amount of the foliage can result in death.
The Controlled Drugs and Substances Act is Canada's federal drug control statute. Passed in 1996 under Prime Minister Jean Chrétien's government, it repeals the Narcotic Control Act and Parts III and IV of the Food and Drugs Act, and establishes eight Schedules of controlled substances and two Classes of precursors. It provides that "The Governor in Council may, by order, amend any of Schedules I to VIII by adding to them or deleting from them any item or portion of an item, where the Governor in Council deems the amendment to be necessary in the public interest."
Pseudotaxus chienii, the whiteberry yew, 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.
Taxus cuspidata, the Japanese yew or spreading yew, is a member of the genus Taxus, native to Japan, Korea, northeast China and the extreme southeast of Russia.
Taxus brevifolia, the Pacific yew or western yew, is a species of tree in the yew family Taxaceae native to the Pacific Northwest of North America. It is a small evergreen conifer, thriving in moisture and otherwise tending to take the form of a shrub.
Phyllocladus aspleniifolius, commonly known as the celerytop pine, is an endemic gymnosperm of Tasmania, Australia. It is widespread and common in Tasmania, with the most abundance in the western highlands. Its ‘leaves’ appear similar to those of a celery plant, hence the common name.
Paclitaxel total synthesis in organic chemistry is a major ongoing research effort in the total synthesis of paclitaxel (Taxol). This diterpenoid is an important drug in the treatment of cancer but, also expensive because the compound is harvested from a scarce resource, namely the Pacific yew. Not only is the synthetic reproduction of the compound itself of great commercial and scientific importance, but it also opens the way to paclitaxel derivatives not found in nature but with greater potential.
Taxus wallichiana, the Himalayan yew, is a species of yew, native to the Himalaya and parts of south-east Asia. The species has a variety of uses in traditional medicine. It is currently classified as endangered by the IUCN.
Taxus floridana, the Florida yew, is a species of yew, endemic to a small area of under 10 km² on the eastern side of the Apalachicola River in mesophytic forests of northern Florida at altitudes of 15–40 m. It is listed as critically endangered. It is protected in reserves at the Torreya State Park and at the Nature Conservancy's Apalachicola Bluffs and Ravines Preserve, and has legal protection under the United States and Florida Endangered Species laws.
Torreya grandis is a species of conifer in either the family Taxaceae, or Cephalotaxaceae. Common names include Chinese Torreya and Chinese nutmeg yew, which refers to its edible seeds that resemble nutmeg and to its yew-like foliage, although it is not related to either nutmeg nor to the true yews belonging to the genus Taxus. Originating in the Jurassic period, about 170 million years ago, it is known as a "living fossil". T. grandis is a large tree that can attain height of 25 metres (82 ft), and possibly as high as 39 metres (128 ft). T. grandis is endemic to eastern and south-eastern China; it is found in the coastal provinces Fujian, Zhejiang, and Jiangsu, as well as in Anhui, Guizhou, Hunan, and Jiangxi inland. Its natural habitat are mountains and open valleys, often by streams, between 200 and 1,400 metres ASL. T. grandis is a precious tree species with multiple values. According to survey data, its economic life is more than a thousand years.
A mitotic inhibitor, microtubule inhibitor, or tubulin inhibitor, is a drug that inhibits mitosis, or cell division, and is used in treating cancer, gout, and nail fungus. These drugs disrupt microtubules, which are structures that pull the chromosomes apart when a cell divides. Mitotic inhibitors are used in cancer treatment, because cancer cells are able to grow through continuous division that eventually spread through the body (metastasize). Thus, cancer cells are more sensitive to inhibition of mitosis than normal cells. Mitotic inhibitors are also used in cytogenetics, where they stop cell division at a stage where chromosomes can be easily examined.
Taxus masonii is an extinct species of conifer in the yew family, Taxaceae, solely known from the middle Eocene sediments exposed in north central Oregon. The species was first described from a series of isolated fossil seeds in chert.
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.