SPRUCE (Picea), an important genus of evergreen coniferous trees of the pine family (Pinaceae), called also spruce-fir, includ ing about 4o species, natives of the cold and temperate regions of the Northern hemisphere. They are pyramidal trees, with whorled branches; thin, scaly bark; linear, spirally-arranged leaves, each jointed near the stem on a separate woody base; and ovoid, oblong or cylindrical spreading cones, which become pend ent when mature. The spruces are readily distinguished from the pines by their solitary instead of fascicled leaves and from the firs in having pendent cones with persistent scales instead of up right cones with deciduous scales.
In an economic sense the most valuable species is the Norway spruce (P. excelsa or P. Abies), native to northern Europe and Asia and well known in plantations in the British Isles and eastern North America, though hardly attaining in cultivation the great height and noble form which it displays in its native woods. In favourable situations it becomes the tallest and one of the state liest of European trees, sometimes rising to a height of 170 ft. and attaining a trunk diameter of 5 to 6 ft. at the base. It has a nearly straight, tapering trunk, throwing out in somewhat irregular whorls its widespreading branches densely clothed with dark clear green foliage. The boughs and their side branches, as they increase in length, have a tendency to droop, the lower tier, even in large trees, often sweeping the ground—a habit that gives a peculiarly picturesque effect. The slender, sharp, slightly curved leaves are scattered thickly around the shoots; the upper ones pressed toward the stem, and the lower directed sideways, giving a somewhat flattened appearance to the individual sprays. The cylindrical cones, 4 to 7 in. long, grow chiefly at the ends of the upper branches.
The Norway spruce is very widely distributed, growing on most of the mountain ranges of Europe from the Pyrenees northward and extending to 68° N., while in Asia it extends eastward to the Lena river and from the Altai mountains to beyond the arctic circle. On the Swiss Alps it is one of the most prevalent and striking of the forest trees. In the lower districts of Sweden it is the predominant tree in most of the great forests; in Norway it constitutes a considerable part of the dense woods of the south ern valleys, flourishing on mountain slopes up to 3,00o ft. and
clothing the shores of some of the fjords to the water's edge.
While less valuable than the pine, the Norway spruce is an im portant timber tree. When produced in close forests the white wood is of compact and even grain and suitable for a great variety of uses. Immense quantities of spruce lumber are imported into Great Britain from north-western Europe. Great quantities also of younger trees are imported as poles, used for scaffolding, lad ders and mining timber. In Norway the wood is very extensively made by hydro-electric power into wood pulp.
As an ornamental tree Norway spruce has been commonly planted in Great Britain since about 1600. It is also grown as a "nurse" for other trees, for shelter for wall-fruit, for cover for game, and for small stakes and poles. As a picturesque tree for park and other ornamental plantation it ranks among the best of the conifers, bearing the smoke of cities better than most of the fir-group, though subject to blight, which gives it an unhealthy appearance after a certain age. In North America the Norway spruce is extensively planted in the eastern States and Canada.
In North America there are seven native species of spruce; of these, three are found in the eastern United States and Canada, two occur in the Rocky Mountain region and two are confined to the Pacific coast. The white spruce (P. glauca or P. alba) is found from Maine to Minnesota northward to Labrador and Hudson bay and north-westward to Bering strait in Alaska. It grows to a height of 15o ft. and a trunk diameter of 4 ft., with cylindrical cones 2 in. long. The white spruce is very valuable for lumber and especially for wood pulp, being the chief species utilized in the Canadian wood pulp industry. The red spruce (P. rubra) occurs from Nova Scotia to New York and southward in the mountains to Tennessee. It is the dominant spruce in the Adiron dack region, attaining a height of 6o to 10o ft., with brownish-red, ovoid cones, about 14 in. long; it is extensively used for lumber and pulp wood. The black or bog spruce (P. mariana), native to swamps from Newfoundland to Alaska and southward to Virginia and Minnesota, commonly 20 to 3o ft. but sometimes 90 ft. high, with small globose cones, is utilized for pulp wood and is the source of spruce gum.