Black Spruce (Picea mariana)

Black Spruce

The Black Spruce (Picea mariana), also known as the "Bog Spruce" or "Swamp Spruce," is a monoecious conifer and evergreen in the Pine Family (Pinaceae). The genus name is from the Latin for "pine" or, more specifically, "pine pitch." The species name refers to Maryland. The lumber from this tree is primarily used for pulp. Younger Black Spruce are cut and sold for Christmas Trees. Chemical products like spruce beer, spruce gum, medical salves and aromatic distillations are made from the sap. It may also be used for fuel.

This tree can grow to a height of 82 feet (25 meters) but is usually shorter. The trunk diameter is as much as one foot (30 centimeters). The crown is open and irregularly conical. The branches are horizontal or droop somewhat, particularly lower on the tree. Lower branches may be leafless to about half the height of a mature tree. The small diameter of the trunk limits the use of this tree for lumber.

The evergreen needles on this tree are blue-green with white linear highlights. The lengths of these needles vary from ¼ inch (6 millimeters) to ⅝ inch (15 millimeters) making them the shortest needles on the spruces around French Hill Pond. Like other spruces, the needles are four-angled and sharp-pointed. Although the needles spread out from the brown twigs from all sides, their short lengths make the branches appear flatter than other spruces. The foliage is darker than other spruces, which accounts for the common name.

Black Spruce Needles

The outer bark is gray to black, scaly and thin. The inner bark is brown but cutting the inner bark will reveal a yellow-brown beneath.

Black Spruce Bark

The cones of the Black Spruce are round or egg-shaped and ⅝ inch (15 millimeters) to about 1¼ inches (30 millimeters) long. They are the smallest, on average, of the spruce cones in the area of French Hill Pond. The scales are fan-shaped and irregularly toothed. The color is a purple-brown, darker than other spruce cones. The cones are usually clustered near the top of the tree. The photograph below shows two Black Spruce cones. The upper cone is nearly round and the lower cone is more egg-shaped. The upper scale on the measuring tape is in inches, the lower scale in centimeters. The seeds are small, brown and winged. One pound (0.45 kilograms) of Black Spruce seeds will contain 404,800 seeds. This tree will also reproduce by rooting a new tree where the branches touch the ground.

Black Spruce Cones

The minium root depth of a Black Spruce is 16 inches (41 centimeters).

Black Spruces will hybridize with Red Spruces. These hybrids will be found in the area of French Hill Pond making identification a bit confusing.

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