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Distinguishing the Spruce Trees of Colorado
by S. K. Wier
All spruces have single, four-sided needles (square in cross-section). Cones are lightweight; cone scales are thin and papery. The cones hang downwards, and fall intact from the tree after the seeds are mature. Cones do not have forked papery strips between the cone scales - that is a Douglas-fir cone.
Engelmann spruce:Needles square in cross-section and 1.0 inch in length or less (rarely to 1 1/8 inch); needles often fairly stiff; not soft; sharp pointed. Mature cones 2.5 inches or less in length; usually 1.5 to 2.0 inches.
Note description of bark for possible confusions with other evergreens, if the bark is used for identification. Engelmann spruce bark may be confused with bark of other trees found in the same location, especially Lodgepole pine.
Colorado Blue spruce:
Needles square in cross-section and usually over 1 inch in length (but not more than 1 1/2 inch); needles stiff and very sharp. You may have a painful experience if you grasp a Blue spruce twig firmly. Mature cones over 2.5 inches in length; often about 3 inches.Bark is almost always grey; orange-brown or red-brown tinges are uncommon and only found underlying grey bark on large older trees.
Some individuals of Engelmann spruce and Douglas fir can have the whitish-blue-green color associated with Blue spruce, on their new growth. This special color, usually associated with Blue spruce, can be a misleading indicator of which tree you are looking at.
Engelmann spruce hybridizes with Blue spruce, yielding trees with intermediate characteristics (though some botanists disagree). If you find a tree that appears to be an Engelmann spruce but whose needles are painfully sharp and stiff you may have found a hybrid.
Copyright © 1998, 1999, 2001, 2010 S. K. Wier
Reproduction, retransmission, or redistribution prohibited without prior written consent of the author. Individuals may print one copy for personal use.