The spruce is a species of evergreen coniferous tree that grows primarily in the colder regions of the Northern Hemisphere. Seven types of spruces grow native in the United States and Canada. Identify a tree as a spruce by its various attributes, with the features different from one species to the next. No spruce trees grow native in the southeastern or central portion of the country, with most species in the northernmost states or in the West.
Some of the spruce species can attain great heights, with the kinds that exist in the western section of the United States typically much larger than those growing across Canada and in the Northeast. The sitka spruce is easily the tallest when full grown, achieving heights as tall as 200 feet in some specimens. The blue spruce of the Rocky Mountains and the Brewer spruce of the Pacific Northwest grow in the 80- to 100-foot range. White spruce and red spruce can top out at 75 feet, while the smallest of the American spruce trees is the 30- to 40-foot-tall black spruce.
The needles on spruce branches vary between species, with their size and color the most obvious differences. White spruce needles are an inch long and typically develop on the upper side of the tree's branches. White spruce needles are green and if you crush them, you may notice an unpleasant odor that the University of Connecticut Plant Database website says is reminiscent of a skunk's spray. The Sitka spruce has silvery, prickly needles as long as 1 1/2 inches, while those of blue spruce give the tree its name with their silver-blue shade. Red spruce has 1/2-inch-long needles that in cross-section have the shape of a square with rounded corners.
Using the cones of spruce trees as a means of identification can be quite revealing, as distinct discrepancies exist among these seed-bearing fruits of the tree. Brewer's spruce has a 2- to 5-inch greenish-purple cone that eventually changes to brown. The cones of black, red and white spruce trees are a bit smaller compared to the cones of western species. Those of red spruce, for example, rarely exceed 2 inches long, while the cones of Englemann's spruce are about 3 inches long. The Norway spruce, a common ornamental introduced from Europe, has cones as long as 7 inches.
Where you discover a spruce tree growing can help you to identify its species. The white and black spruces share a similar range, from New England through the Great Lakes states and across most of Canada and well into Alaska. Red spruce grows through New England and into the Appalachian Mountains. Sitka spruce is native to coastal Alaska southward along the Pacific Coast to northern California. Blue spruce, also called Colorado spruce, is native to the Rocky Mountain states.
Most spruce trees grow in moist and fertile soil. The crowns develop to look like a church spire, pointed at their very tops. Any twigs lacking needles have a rough feel to them and appear warty. Spruce bark normally looks scaly. The spruce is the kind of tree that can often grow in pure stands, with many spruces of the same type in one area.