Northern Ontario Plant Database
Tsuga canadensis (L.) Carrière
En: eastern hemlock, Canadian hemlock, black hemlock
Pinaceae (Pine Family)
General: A tall, slow-growing, shade-loving conifer, 30–50 m tall, with graceful branches; the terminal shoot (leader) drooping. Bark grayish-brown and smooth when young, furrowed and reddish-brown on mature trees. Twigs smooth (glabrous), older twigs bearing persistent leaf stalk (petiole) bases.
Needles: Spirally arranged but appearing 2-ranked, simple, evergreen, petioled. Leaf blades linear, 0.8–1.3 mm long, flat, dark green above, with 2 silvery lines below (overlying rows of stomata); blunt to rounded at the apex, margins nearly entire, bearing a few minute teeth toward the tip of the needle.
Cones: Unisexual, bearing male and female cones on the same tree (plants monoecious). Male cones tiny, emerging from the axillary buds of the previous year's needles; female cones terminal, stalked, pendant; mature seed cones 1.3–2 cm long, ovoid, brown, with rounded, entire scales; maturing the first year, each cone scale bearing 2 winged seeds; seed body 1.5–2 mm long, the thin, asymmetrically attached wing, 6–8 mm long.
Habitat and Range: Rich, shaded mixedwood forests, preferring moist to very moist sites with good drainage and acidic soils, particularly on sandy, rocky, or glacial till soils. A north-temperate species of eastern North America, its range extends throughout the southern boundary of northern Ontario.
Internet Images: The Tsuga canadensis webpage from the Trees of Wisconsin website. Click on the smaller images to view larger, more detailed photos.
The leaves and cones, and twig of Tsuga canadensis, from the Univ. of Wisconsin's Dendrology website.
Images of lower surface of needles, male, pollen-bearing cones, and mature seed cone from the University of New Brunswick forestry photo gallery.
The eastern hemlock, Tsuga canadensis, webpage from Walter Muma's OntarioTrees.com website.
The Tsuga canadensis webpage from the Virginia Tech Dendrology website.
The Tsuga canadensis webpage from the USDA Silvics of North America website.
Similar Species: The flat, nearly 2-ranked needles of Tsuga canadensis may be mistaken for Abies balsamea, the balsam fir, but the latter species has longer, sessile needles, 2–3 cm long, and larger erect seed cones, 5–10 cm long, which are borne at the top of the crown on the previous year's growth. The axis of the fir cones is persistent, but the cone scales dehisce with the seeds. See also the Abies balsamea webpages from the Trees of Wisconsin Abies and Virginia Tech Dendrology [ websites.
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