''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 sin ...

native to central and eastern

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, 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 The Ohio River () is a river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing in a southwesterly direction from Pittsburgh, Pennsylvania, to its river mouth, mouth on the Mississippi Riv ...

. It is, however, found as a rare ice age

relict A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a r ...

in some coves of the Appalachian Mountains. The southernmost colonies are known from Ashe and Watauga Counties in

North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

Description and ecology

It is usually a sprawling

shrub A shrub or 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 by their multiple ...

, 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: Common meanings * 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) Arts and entertainment * ''Bark'' (Jefferson Airplane album), ...

. The

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

( 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 In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...

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 of berries in the cul ...

-like structure called an

aril An aril (), also called 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 ova ...

, open at the end. The seeds are eaten by thrushes,

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 (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

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 comparable with gynomonoecy, andromonoecy and trimonoecy, and contras ...

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''. Native Americans 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 a ...

. They are also been said to have used yew twigs in steam baths to help alleviate

. Again, the plant is quite toxic and modern

herbalists Herbal medicine (also called herbalism, phytomedicine or phytotherapy) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. Scientific evidence for the effectiveness of many herbal treatments ...

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

Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...

Québec Quebec is Canada's largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, New Brunswick to the southeast and a coastal border ...

and

Atlantic Canada Atlantic Canada, also called the Atlantic provinces (), is the list of regions of Canada, region of Eastern Canada comprising four provinces: New Brunswick, Newfoundland and Labrador, Nova Scotia, and Prince Edward Island. As of 2021, the landma ...

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 app ...

s, which have been a focus for

cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...

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, used in the production of

paclitaxel 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 b ...

. 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 Plants described in 1785 Trees of Northern America