Most spruce species are found in and west of the Rocky Mountains.
The term spruce has at least three separate and distinct meanings. Firstly, spruce in scientific terminology refers to the 40 species of the genus Abies. The pine family, of which spruces are a part, contains 11 general species in total and 210 species. Second, firs are commonly used by laypeople to refer to any evergreen conifer. And thirdly, fir trees are used to designate artificial Christmas trees of any kind.
Douglas firs are the most common type of Christmas tree, although they are not a true spruce.
In scientific categorization, spruces are actually in a separate category from other trees in the pine family, which includes pines, spruces, larches, etc. They can be distinguished by their leaves, often called needles. The needles of a true spruce grow from the branch and leave scars on the branch when they fall. The cones grow vertically, with each scale containing two seeds. When the cones fall, they leave a small vertical attachment on the branch. Other pines have different leaf and cone arrangements.
A fir Christmas tree can feature a tree skirt.
There are 12 species of spruce native to the United States, most are found primarily in the Rocky Mountains and west of it. The top ten Westerners include four that can grow to 200 feet (60 m), including California spruce, noble pine, Pacific silver pine, and white pine. The wood of western spruces is of inferior quality to that of pines and spruces. In the eastern United States, as well as Canada, balsam fir is found, which is one of the most popular choices for Christmas trees and other ornamental uses. Balsam spruce characteristically grows to a height of 12 to 18 m (40 and 60 ft).
Fir trees also grow in other parts of the world, including Central America, Europe, North Africa and Asia. An example of a species native to Europe and Asia is the silver spruce. Used for ornamental purposes as well as wood, it grows up to 150 feet (45 m). Its wood is not only used for carpentry, but also as a source of turpentine and pitch.
People may be surprised to learn that Douglas pine is not a true pine, although it is, of course, in the pine family. Douglas fir comprises about six species of pine trees found in western North America and eastern Asia. The tree species most commonly called by this name is, like balsam fir, a popular Christmas tree.