Northern Ontario Plant Database

Plant Description

Taxus canadensis Marshall

En: Canada yew, ground hemlock
Fr: li du Canada, buis de sapin, sapin trainard
Oj: baagoodag

Taxaceae (Yew Family)

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General: A low, evergreen shrub, to 2 m tall, with numerous, graceful, spreading branches; colonies form vegetatively through layering of branches. Warning: Leaves, stems, and seeds contain taxol, a poisonous alkaloid used in the production of anti-cancer drugs. Seeds and wilted needles are poisonous to horses and cattle, but not to deer or moose.

Stems/twigs: Young twigs and branches are green, smooth (glabrous), and flexible, but older stems are brown and woody.

Needles: Evergreen; attached spirally to twigs by their decurrent petioles, but arranged in flat planes due to the twisting of the petioles to either side of the branches. Needles are linear, flat, soft, and 1-2.5 cm long by 1-2.5 mm wide. The upper needle surface is dark green; the lower surface is green with a single, prominent vein. Needle margins are entire and curved under slightly (barely revolute); needles end in an abrupt, sharply pointed (mucronate), soft tip.

Reproductive structures/cones: Unisexual, with separate male and female reproductive structures borne on the same plant (monoecious). Cones are situated on the under surface of branches in the needle axils. The small male (staminate) cones are composed of a stalked, globose cluster of 8-10 stamens borne in a cup-shaped cone of thin, small bracts. Female cones are reduced to a single, small ovule (the embryonic seed) subtended by a few bracts. Pollination and fertilization occur in the spring. The mature seed is hard, ovoid, slightly flattened, olive-green to brown, and surrounded by a fleshy, red aril, 5-10 mm long, which is open at one end. Yew arils are edible but slimy; all other parts of the plant, including the seeds, are considered toxic.

Habitat and Range: Rich, moist, shaded understories of coniferous or mixedwood forests, thickets, and ravines. Canada yew is native to boreal northeastern North America, with a range that extends from western Newfoundland to eastern Manitoba, with a small disjunct population in central Labrador. It occurs throughout forested regions of Ontario, but rarely occurs north of 50°N (Soper & Heimburger 1982).

Similar Species: Young balsam fir (Abies balsamea (L.) Mill.) plants may be mistaken for Canada yew. Both balsam fir and Canada yew have needles arranged in flat planes, but fir has blunt-tipped needles attached directly to the twig by flat, round bases that are not decurrent. Also, balsam fir is resinous, while the wood of Canada yew lacks resin ducts.