Spruces have needles less than 20mm (3/4 inch) long with square cross-sections. They never occur in bunches, just one needle per node. They can be confused with Balsam Fir (Abies balsamea) but Firs have needles with flattened cross-sections. If you can roll a needle in your fingertips then it is a spruce.
Balsam Fir and Spruce Needles and Branchlets
Michigan has two native spruces, Black Spruce (Picea mariana) and White Spruce (P. glauca). Norway Spruce (P. abies) is now naturalized into the state.
Black Spruce Branchlets
Black Spruce pegs and cones
Black Spruce has needles shorter than 16mm (5/8 inch) and densely pubescent, meaning furry, first year branchlets. The needle bases, which sit on a peg-like projection, are difficult to see. These peg-like projections stick out at 90 degrees to the twig. If cones are present, they are about as wide as they are long. In southern Michigan, Black Spruce grows only in cool bogs. North of Bay City, it will also grow in upland forests and interdunal swales. Even in the north, it prefers a damp habitat and often occurs with Tamarack (Larix laricina) and White Cedar (Thuja occidentalis). The common name refers to the dark needles this tree normally has.
White Spruce needles and cone
White Spruce has needles that are normally longer than 16mm (5/8 inch) and hairless first year branchlets. The needle bases are easily seen. The peg-like projections point forward at approximately 60 degrees from the twig. Cones are two to three times longer than wide. The tree’s native range is north of West Branch. It grows in similar habitats as Black Spruce but will also thrive in drier locations. The common name refers to the waxy layer on the young needles.
Norway Spruce needles and cone
The native range of Norway Spruce is central and northern Europe. It is escaping throughout Michigan. The branchlets droop and its cones are large, approximately 130mm (5 inch) long. Norway Spruce is commonly planted and beginning to escape into natural areas. Its needles are stiff and have rows of minute openings properly called stomata.
Norway Spruce stomata
Copyright 2014 by Donald Drife
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This is one of the best documented descriptions of the distinctions between the two species. Thank you very much for such fine attention to detail. I’ve been looking for some time now, stumbled on your site, and was so happy to discover such a succinct summary.
I too have searched the internet for help distinguishing White Spruce from Norway Spruce. These photographs and written descriptions are the best I have found. What is still unclear to me is the stomata on the Norway Spruce needles. When I look at the photos, both the White Spruce and Norway Spruce needles appear to have small dots along their length. Also, what about smell? Another website suggested crushing the needles of White Spruce produces a skunk-like smell, whereas crushing the needles of the Norway Spruce produces a pleasant smell. Can anyone else verify this?
According to Barnes Michigan Trees White Spruce needles have a disagreeable odor. Stomata is not a good key character for distinguishing Norway from White Spruce.