Maine Tree Species Fact Sheet

Common Names: Hemlock (Eastern Hemlock, Canadian Hemlock)
Botanical Name: Tsuga canadensis
Tree Type: Coniferous

Physical Description:

Growth Habit: The hemlock is a large tree with a medium growth rate.  It grows only where there is moist, cool air and can be grown in full-sun or full-shade.  The bark is divided into narrow, rounded ridges covered with thick scales, and varies in color from cinnamon-red to gray.  The needles are 1/3-2/3 inches long, dark yellow-green with a lustrous upper surface and whitish under surface.  They are flat, tapering and generally rounded at the apex and become progressively shorter towards the tip of the twig.  The light brown, oblong cones are approximately 3/4 inches in length, pendant and suspended on short slender stalks.

Height: Hemlock reaches an average height of 60-70 feet, with a trunk diameter of 2-3 feet.

Shape: The hemlock has small evergreen needles and thin wispy horizontal stems that turn down at the ends and form a pyramidal tree.

Fruit/Seed Description/Dispersal Methods:

Hemlock is monoecious with male and female strobili born on the same branch.  Male strobili release pollen to the wind in spring, beginning in April.  Fertilization occurs over a 6-week period following pollination, and cones ripen over the summer opening in the fall to release seeds to the wind.  Seed dispersal begins in October and continues through the winter.

Range Within Maine:

Hemlock is found in scattered stands in nearly every part of the state.  It grows best on moist, cool sites.   This species is hardy in Zones 4-7.

Distinguishing Features:

The terminal shoot is pendulous and bends away from prevailing winds, often towards the east.

Interesting Facts:

Hemlock wood is coarse, brittle when very dry, light, strong and difficult to work.  It is used for framing, sheathing, roof boards, timbers and pulp.  The bark was once valuable for tanning.

Relationship to Wildlife:

Numerous animals, especially deer, and some bird feed on hemlock.

Landscape Use:

Hemlock can be repeatedly sheared for a dense tree or dense hedge effect.  It is not appropriate to use it as a windbreak in exposed sites or as a roadside screen planting where it can be damaged from winter salt spray.  Hemlock does not tolerate poorly drained soils or wet sites.

Common Problems or Pests of the Tree in Maine:

Hemlock is bothered by several insects, diseases and problems including the hemlock woolly adelgid, molds, damping-off fungi and root rots, hemlock borer, hemlock looper, white grubs of the strawberry weevil, hemlock scale, gypsy moth and drought.

References:

A Boundary Waters Compendium: www.rook.org/earl/bwca/nature/trees/pinusstrob.html

The Peterson Field Guide Series: A Field Guide to Eastern Forests. Kricher, John C. Houghton Mifflin Co. 1988.

Forest Trees of Maine, Twelfth Edition.  Maine Forest Service/Department of

Conservation. 1995.

The Ohio State University Plant Dictionary:

http://www.hcs.ohio-state.edu/hcs/TMI/Plant;ost/pi_robus.html

TreeGuide, Inc.  www.treeguide.com

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