PINACEAE 



The Spruces 

 Characteristics of the Genus Picea Dietr. 



HABIT. Evergreen trees with sharp-pointed, pyramidal 

 crowns, and straight, tapering trunks; branches in regular 

 whorls. 



LEAVES. Spirally arranged, linear, sessile, stiff, and single; 

 extending from all sides of twigs; persistent 7-10 years, but 

 deciduous when dried; 4-angled or flattened; when falling, 

 leaving basal peglike projections (sterigmata) on the twig. 



FLOWERS. Monoecious, catkin-like, solitary; male, or pol- 

 len-bearing, auxiliary, yellow to red or purple, Y^-l inch long, 

 consisting of numerous spirally arranged scales, each bearing 

 two pollen sacs; female, or cone- and seed-producing, terminal, 

 erect, yellow-green or red, %-l|4 inches long, consisting of 

 numerous 2-ovuled, bracted scales. 



FRUIT. Woody, pendent cone; matures in one season; 

 borne mostly near top of crown; scales numerous, thin, un- 

 armed, persistent, much longer than bracts. Seed: 2 under 

 each fertile scale, small, compressed; highly buoyant with thin 

 wing. 



TWIGS. Roughened by sterigmata. Winter buds: ovoid or 

 conical, of overlapping scales, and usually not resinous. 



BARK. Thin and scaly (furrowed on old trunks in blue 

 spruce). 



WOOD. Light, soft, resilient, fine-textured, long-fibered and 

 straight-grained; small, scattered resin ducts; not resinous; 

 high satiny luster; strong for weight; highly important for paper 

 pulp, lumber, boxes, etc. 



SILVICAL CHARACTERS. Tolerant; no taproot and gen- 

 erally shallow-rooted. Natural enemies: fire, leaf aphis {Adelges 

 abietis) which causes conelike gall, spruce budworm {Harmologa 

 fumiferana), which often destroys young stands, and white pine 

 weevil (Pissodes strobi). 



HABITAT. Cool, moist sites; typically in swampy areas or 

 along the margins of streams and lakes. 



GENERAL. This genus contains about 40 species, largely 

 restricted to cooler regions in the Northern Hemisphere. In 

 North America there are 7 indigenous species. The Norway 

 spruce, Picea abies (L.) Karst., characterized by cones 4—7 inches 

 long, is commonly planted throughout the United States and 

 has become naturalized in the east. 



[48] 



