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Tsuga canadensis (Eastern hemlock): Information.
Identifying characteristics: The eastern hemlock is a 60- to 70-foot evergreen conifer with a dense, pyramidal crown and a trunk diameter of 2 to 3 feet. The leading shoots are typically drooping and the horizontal branches of open-grown trees often extend nearly to the ground. The leaves are flat, linear and one- to two-thirds of an inch long, persisting on the tree for 2 to 3 years. The leaves are spirally arranged but appear two-ranked, with those on the upper surface of the twig shorter and often upside-down on a twisted petiole. The leaves are dark green above, with two white lines formed by the stomata on the underside. The cones are produced on the previous season's growth near the tips of the branches. They are small, with thin, papery scales, which are noticably two-toned, being darker where scales overlapped. Trees take 20 to 40 years to begin seed production, eventually producing heavy crops every 2 to 3 years and lighter crops in between. Seeds are egg-shaped, winged and less than 0.1 inches long. The bark is gray and scaly on young trees, later becoming deeply furrowed and ridged. Hemlock bark was once an important source of tannin. Similar species: Ecology: Distribution: This species is native to the northeastern US and southeastern Canada and will grow well in Iowa only when planted in cool, moist, sheltered positions in eastern and central Iowa. Habitat: The location of this particular group of trees on the ISU campus is ideal, mimicking the microclimate of the cool, shaded, moist valleys and canyons where these trees would naturally occur. Hemlocks are fast-growing, but require abundant moisture. The leaf litter formed by fallen leaves produces, over the years, an acid soil which may discourage competition from some plants. Needle blight is a disease that may cause some leaves to turn brown and die, but this species is subject to very few diseases in Iowa. Uses: Wood: The moderately soft, moderately strong wood is lightweight, coarse and splintery. It is often knotty due to the persistent branches and is occasionally used in rough, general construction and for pulp. It sparks and pops considerably when burned and is therefore not suitable for use as firewood. Wildlife: Forming a dense, evergreen cover, the eastern hemlock is an important shelter tree in winter for white-tailed deer, ruffed grouse and wild turkey. Deer may browse the trees in winter and chickadee, pine siskin and crossbills depend on this species for cover and seeds. The deadly beverage that Socrates drank was not from this tree but a plant of the parsley family. Native Americans made a medicinal tea from the leaves of the eastern hemlock and used the inner bark as a poultice. Horticulture: This tree is sensitive to drying winds and drought, and is therefore generally not recommended for planting in Iowa.

Tsuga canadensis (Eastern hemlock): Information.

Identifying characteristics:
The eastern hemlock is a 60- to 70-foot evergreen conifer with a dense, pyramidal crown and a trunk diameter of 2 to 3 feet. The leading shoots are typically drooping and the horizontal branches of open-grown trees often extend nearly to the ground. The leaves are flat, linear and one- to two-thirds of an inch long, persisting on the tree for 2 to 3 years. The leaves are spirally arranged but appear two-ranked, with those on the upper surface of the twig shorter and often upside-down on a twisted petiole. The leaves are dark green above, with two white lines formed by the stomata on the underside. The cones are produced on the previous season's growth near the tips of the branches. They are small, with thin, papery scales, which are noticably two-toned, being darker where scales overlapped. Trees take 20 to 40 years to begin seed production, eventually producing heavy crops every 2 to 3 years and lighter crops in between. Seeds are egg-shaped, winged and less than 0.1 inches long. The bark is gray and scaly on young trees, later becoming deeply furrowed and ridged. Hemlock bark was once an important source of tannin.

Similar species:

Ecology:
Distribution: This species is native to the northeastern US and southeastern Canada and will grow well in Iowa only when planted in cool, moist, sheltered positions in eastern and central Iowa.

Habitat: The location of this particular group of trees on the ISU campus is ideal, mimicking the microclimate of the cool, shaded, moist valleys and canyons where these trees would naturally occur. Hemlocks are fast-growing, but require abundant moisture. The leaf litter formed by fallen leaves produces, over the years, an acid soil which may discourage competition from some plants. Needle blight is a disease that may cause some leaves to turn brown and die, but this species is subject to very few diseases in Iowa.

Uses:
Wood: The moderately soft, moderately strong wood is lightweight, coarse and splintery. It is often knotty due to the persistent branches and is occasionally used in rough, general construction and for pulp. It sparks and pops considerably when burned and is therefore not suitable for use as firewood.

Wildlife: Forming a dense, evergreen cover, the eastern hemlock is an important shelter tree in winter for white-tailed deer, ruffed grouse and wild turkey. Deer may browse the trees in winter and chickadee, pine siskin and crossbills depend on this species for cover and seeds. The deadly beverage that Socrates drank was not from this tree but a plant of the parsley family. Native Americans made a medicinal tea from the leaves of the eastern hemlock and used the inner bark as a poultice.

Horticulture: This tree is sensitive to drying winds and drought, and is therefore generally not recommended for planting in Iowa.