''Taxus canadensis'', the Canada yew or Canadian yew, is a

conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...

native to central and eastern

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

, thriving in swampy woods, ravines, riverbanks and on lake shores. Locally called simply "yew", this species is also referred to as American yew or ground-hemlock. Most of its range is well north of the

Ohio River The Ohio River is a long river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing southwesterly from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illino ...

. 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 Watauga can refer to: ;Places *Watauga, Kentucky * Watauga County, North Carolina * Watauga, South Dakota * Watauga, Tennessee * Watauga, Texas ;Bodies of Water * Watauga Lake in Tennessee * The Watauga River in North Carolina and Tennessee ;Shi ...

Counties in

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...

Description and ecology

It is usually a sprawling

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

, 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 Bark may refer to: * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Places * Bark, Germany * Bark, Warmian-Masurian Voivodeship, Poland Arts, ...

. The

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

( needles) are lanceolate, flat, dark green, long and broad, arranged in two flat rows either side of the branch. The seed cones are highly modified, each cone containing a 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 gymnosperm and angiospe ...

partly surrounded by a modified scale which develops into a soft, bright red

berry A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit, although many pips or seeds may be present. Common examples are strawberries, raspb ...

-like structure called an

aril An aril (pronounced ), 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 see ...

, open at the end. The seeds are eaten by

thrushes The thrushes are a passerine bird family, Turdidae, with a worldwide distribution. The family was once much larger before biologists reclassified the former subfamily Saxicolinae, which includes the chats and European robins, as Old World flycat ...

waxwing The waxwings are three species of passerine birds classified in the genus ''Bombycilla''. They are pinkish-brown and pale grey with distinctive smooth plumage in which many body feathers are not individually visible, a black and white eyestripe, ...

s and other

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

s, which disperse the (highly toxic) hard seeds undamaged in their droppings. The male cones are globose, 3 mm in diameter. It is a

monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is conne ...

plant – one of the few in the genus.

Uses and traditions

All parts of Canadian yew, save the aril, are

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

; it is, however, thought to be of lower toxicity than '' T. baccata''. Tribes in its native range used small quantities of yew leaf tea topically or internally for a variety of ailments – notably

rheumatism Rheumatism or rheumatic disorders are conditions causing chronic, often intermittent pain affecting the joints or connective tissue. Rheumatism does not designate any specific disorder, but covers at least 200 different conditions, including art ...

. Tribes are also been said to have used yew twigs in

steam baths A steam bath is a steam-filled room for the purpose of relaxation and cleansing. It has a long history, going back to Greek and Roman times. History The origins of the steam bath come from the Roman bath, which began during the height of the R ...

to help alleviate

. Again, the plant is quite toxic and modern

herbalists Herbal medicine (also herbalism) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern remed ...

prefer safer, more effective herbs. ''Taxus canadensis'' is also being harvested in northern

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

Québec Quebec ( ; )According to the Government of Canada, Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is ...

and

Atlantic Canada Atlantic Canada, also called the Atlantic provinces (french: provinces de l'Atlantique), is the region of Eastern Canada comprising the provinces located on the Atlantic coast, excluding Quebec. The four provinces are New Brunswick, Newfoundlan ...

as the plant is a source of the class of poisonous chemicals known as

taxane Taxanes are a class of diterpenes. They were originally identified from plants of the genus ''Taxus'' (yews), and feature a taxadiene core. Paclitaxel (Taxol) and docetaxel (Taxotere) are widely used as chemotherapy agents. Cabazitaxel was FDA ap ...

s, which have been a focus for

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

research. ''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 10-Deacetylbaccatins are a series of closely related natural organic compounds isolated from the yew tree (Genera ''Taxus''). 10-Deacetylbaccatin III is a precursor to the anti-cancer drug docetaxel (Taxotere). 10-deacetylbaccatin III 10-O-acet ...

, used in the production of

paclitaxel Paclitaxel (PTX), sold under the brand name Taxol among others, is a chemotherapy medication used to treat a number of types of cancer. This includes ovarian cancer, esophageal cancer, breast cancer, lung cancer, Kaposi's sarcoma, cervical cancer ...

. 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. Taxus canadensis 5443106

References

External links

* {{Taxonbar, from=Q1723511 canadensis Least concern plants Flora of West Virginia Trees of the Northeastern United States Plants described in 1785 Trees of Eastern Canada