The two species can be distinguished by their needles and cones. Western hemlock has needles of varying lengths that only grow out of the sides of the branch, so they lay flatter — as opposed to the circular branches of mountain hemlock, with needles pointing in all directions.

In the Landscape: Some consider the Mountain Hemlock to be the best native conifer for a small garden. It can be used as a specimen tree in a container or to create a focal point in a rock garden. It creates a picturesque scene when planted in clumps or drifts.

Poison-hemlock grows throughout the United States. It is very toxic and sheep, cattle, swine, horses, and other domestic animals are poisoned by eating small amounts of green or dried plant. It is also extremely poisonous to humans.

75 to 100 feet
GENERAL BOTANICAL CHARACTERISTICS : Mountain hemlock is a native, slow-growing, coniferous, evergreen tree usually 75 to 100 feet (23-30 m) tall and 2.5 to 3.5 feet (0.8-1 m) in diameter [59]. However, it takes on a variety of growth forms to adapt to subalpine conditions.

The relatively short growing season (frost-free period) ranges from 95 to 148 days in southwestern British Columbia (9,45) and from 49 to 63 days in the central Sierra Nevada (64).

Plant mountain hemlock in full sun to part shade in well-drained soil. Occasional watering. It can grow well in a container for many years.

Several articles recommend burning hemlock after pulling, but the smoke may contain toxins that could cause severe illness and even death.

Native to Europe, western Asia, and North America, poison hemlock (Conium maculatum) is now naturalized in almost every state in the United States. Infestations occur along roadsides, field margins, ditches, marshes, meadows, and low-lying areas, but poison hemlock prefers shaded areas with moist soil.

Hemlock has narrow, flat needles that are usually only one inch long. Fir has longer (3 inches on average) and more flat needles compared with hemlock. Upper surface of needles is usually green and shiny, while bottom side is covered with whitish stomata arranged in two rows.

Elevation: The elevational range of western hemlock is from sea level to 7,000 feet (2,130 m). On the coast, western hemlock develops best between sea level and 2,000 feet (610 m); in the Rocky Mountains, it develops best between 1,600 and 4,200 feet (490-1,280 m) [57].

It does not usually perform well in eastern states. Hardy to USDA Zone 5 Native to southern Alaska along the Pacific coast to British Columbia and in mountains to central California, also southeast of B.C. in the Rocky Mountains of northern Montana, Idaho.

T. mertensiana typically initiates clumps within its range, but such clumps often also support Abies amabilis or Cupressus nootkatensis. On drier sites, such as in the Rocky Mountains, clumps are commonly initiated by Pinus albicaulis, and a “skirt” of young Abies lasiocarpa then grows up around it.

The crown is narrowly conical, sometimes with a tilted or drooping lead shoot, with spreading, hanging branches. Bark is charcoal gray to reddish brown, deeply fissured, square-cracked, and scaly.

Seed cones are smaller, 1.2 to 2.4 inches (30 – 60 mm) long, 0.47 to 1 inch (12 – 25 mm) broad when open, with 50 to 80 scales. Tsuga mertensiana subsp. mertensiana var. jeffreyi — Jeffrey’s mountain hemlock. Mixed with var. mertensiana, rare. Leaves greener, less glaucous above, paler below; seed cones indistinguishable from the type.