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Picea pungens

(Colorado spruce)

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Picea pungens, first described in 1879 by Georg Engelmann (1809–1884) is commonly known as Blue spruce, Colorado Blue spruce, White spruce, Silver spruce, or Parry spruce; as épinette bleue  in French Canadian and as pino real in Spanish. It is the state tree of Colorado.

10721_1Description. Colorado spruce is an evergreen coniferous species of tree which will grow to mature heights of 165 feet (50 m) tall with a trunk 5 feet (150 cm) in diameter at breast height.

  • Crown is broadly conic in shape.
  • Bark is gray-brown in color.
  • Branches grow slightly to strongly drooping; non-pendant twigs are stout and yellow-brown in color, usually glabrous.
  • Buds are dark orange-brown, 0.24 to 0.48 inch (6 – 12 mm) in size, the apex rounded to acute.
  • Foliage is needle-like, 0.6 to 1.2 inches (1.6 – 3 cm) long, 4-angled in cross section, rigid, blue-green in color, bearing stomata on all surfaces, with a spine-tipped apex.
  • Pollen cones are red in color, growing in whorls of 3 to 5 at the proximal end of new shoots, primarily borne in upper crown.
  • Seed cones are also borne in the tree’s upper crown. They are pale green or red when fresh, ripening to pale buff brown, 2 to 5 inches (5 -12 cm) long with elliptic to diamond-shaped scales, widest below middle. Seed cones mature in August; seed shed is from September into winter.
natural range of Picea pungens
natural range of Picea pungens

Distribution. This species is native to USA — the states of Idaho, Wyoming, Utah, Colorado, New Mexico and Arizona, growing in the montane zone at elevations varying from 5800 to 8800 feet (1830 – 2740 m) above sea level in the northern range of the species, and to 6800 to 9800 feet (2130 – 3050 m) in southern areas. It prefers areas where the climate is cool and summer-wet, with mean winter minimum temperatures of 12° to 48°F (-11.1° – 8.9°C) and mean summer maximum temperatures of 70° to 72° F (21.1° – 22.2°C). Average annual precipitation varies from 18 to 24 inches (460 – 610 mm), with half of the annual precipitation falling during the growing season. It is the most drought-tolerant species of Picea in North America. It is hardy to USDA Zone 3 (cold hardiness limit between -40° to -30° (-39.9° to -34.4°C).

 

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