Norway Spruce
Picea abies
Pine family (Pinaceae)

Description: This coniferous tree is 50-120' tall, forming an unbranched straight bole and a crown that is conical to oblongoid in shape. Toward the base of a mature tree, the trunk is 1-3' across. The trunk bark is gray and rough-textured, becoming scaly with age. Both crustose lichens and algae often colonize its bark. Numerous lateral branches originate along the entire length of the bole. These lateral branches are slightly incurved and ascending. Along the length of each lateral branch, there are several drooping branchlets that divide into divergently branched twigs. The bark of these branches and branchlets is slightly rough and gray, while the twigs are pale yellow to reddish brown. Along the smaller branches, branchlets, and twigs are short needle-like leaves about -1" long. These needle-like leaves are medium to dark green, 4-angular, and slightly flattened with blunt tips; they are stiff-textured and curve slightly toward the tips of each branch or twig. Along the sides of each leaf, there are pairs of faint white lines that are formed by rows of stomata (air pores). At the base of each leaf, there is a short peg-like extension of the twig from which the leaf breaks off when it turns brown from age. Individual leaves are evergreen, persisting on a tree for 3-7 years. They have a pine-like fragrance.



Norway Spruce is monoecious, forming separate male and female cones on the same tree during mid- to late spring. Male pollen cones are produced from the axils of the needle-like leaves; they are -1" in length, oblongoid-ovoid in shape, and purplish red to whitish pink. Female seed cones are produced from the tips of twigs; they are initially pink to reddish pink and oblongoid-ovoid in shape, but change color and become longer after the blooming period. At this stage, both male and female cones are more or less erect. Afterwards, fertile seed cones become green and hang downward; they are covered with overlapping appressed scales. At maturity, these seed cones become brown to gray-brown and slightly woody from their thin scales; they are 4-7" in length and cylindrical in shape. Individual scales are about -1" in length and -" across; they are obovate-rhombic in shape, glabrous, and irregularly toothed to toothless along their outer margins. Hidden behind each scale, is a pair of winged seeds (not always fully developed). Each seed body is 3-5 mm. in length, while its membranous wing is 10-15 mm. in length. The winged seeds are distributed by the wind. The root system consists of shallow lateral roots. This tree can reproduce vegetatively by "layering" when its lower branches become inserted in moist soil.


Cultivation: The preference is partial to full sun, well-drained moist conditions, and an acidic fertile soil consisting of sandy loam or other soil types. A cool, moist, and humid climate is also preferred, although this tree can tolerate a temperate climate that is more warm and dry.  Growth is relatively fast for a conifer during the early stages of development.. Under favorable conditions in North America, this tree will live 100-200 years, if not longer. Where the soil has a low pH, it is vulnerable to acid rain.

Range & Habitat: The non-native Norway Spruce has naturalized only in the NW corner of Illinois in Jo Daviess County, where it is rare. It was introduced into North America from Europe, where it is native.  In Illinois, this tree has naturalized in a woods (Mohlenbrock, 2002), where it is apparently successfully reproducing. Norway Spruce is far more common in cultivation, where it used as a landscape tree, a windbreak tree, and a plantation tree (for Christmas trees and other commercial markets).

Faunal Associations: A number of insects feed on the foliage, bore through bark, or suck plant juices from Norway Spruce and other spruce trees (Picea spp.).  These insects include the caterpillars of such moths as Choristoneura fumiferana (Spruce Budworm), Elaphria versicolor (Variegated Midget), Endothenia albolineana (Spruce Needle Miner), and Feralia comstocki (Comstock's Sallow); see the Moth Table for a more complete listing of these species. Another group of insect feeders include the wood-boring larvae of such long-horned beetles as Monochamus marmorator (Balsam Fir Sawyer), Monochamus titillator (Southern Pine Sawyer), and Semanotus litigiosus (Fir Tree Borer); see the Long-Horned Beetle Table for a more complete listing of these species. Other miscellaneous insect feeders include Adelges abietis (Eastern Spruce Gall Adelgid), Chionaspis pinifoliae (Pine Needle Scale), Physokermes piceae (Spruce Bud Scale), the aphids Cinara pinicola and Cinara pruinosa, the plant bug Psallovius piceicola, the weevils Hylobius pales (Pales Weevil) and Pissodes approximatus (Northern Pine Weevil), and the root-feeding larvae of Strigoderma arboricola (False Japanese Beetle). An arachnid invertebrate species, Oligonychus ununguis (Spruce Spider Mite), also feeds on these trees.



Among vertebrate animals, the seeds of spruces are eaten by such birds as the Red Crossbill, White-Winged Crossbill, Red-Breasted Nuthatch, Slate-Colored Junco, and Pine Siskin; the Red Squirrel also consumes the seeds. Norway Spruce is one one of the least preferred sources of food of White-Tailed Deer, although Cottontail Rabbits occasionally browse on seedlings of this tree during the winter. Because of their dense branching structure and evergreen foliage, spruce trees are used as nesting habitat by such birds as the Golden-Crowned Kinglet, Blackburnian Warbler, and Blackpoll Warbler; this generally occurs in boreal areas to the north or northeast of Illinois. Some birds like to roost in spruces, particularly during the winter, because of the protective cover that they provide.


Photographic Location: Near the veterinarian building of the University of Illinois in Urbana, Illinois.



Comments:
The wood of Norway Spruce is used to make furniture, musical instruments (pianos & violins), pulp, and in general construction. It is light-colored, light-weight, rather soft, and reasonably strong. Norway Spruce has the longest seed cones of any spruce (Picea sp.) in Illinois; they exceed 4" in length, while the seed cones of other spruces within the state (which are largely cultivated) are less than 4" in length. Spruces resemble firs (Abies spp.), but their mature seed cones hang downward from their branches. In contrast, the mature seed cones of firs are erect. Spruces produce their leaves individually along their twigs and branches, while pines (Pinus spp.) produce their leaves in clusters (typically 2-5 leaves per cluster). Thus, spruces are fairly easy to distinguish from firs and pines. Like Norway Spruce, other spruces in Illinois are rarely observed in the wild. The coniferous trees in this group are more typical of boreal regions or mountainous areas where the climate is more cool and damp.


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