Blue Spruce ,Colorado Spruce
The Blue Spruce or Colorado Spruce (Picea pungens), is a species of spruce native to western North America, from southeast Idaho and southwest Wyoming, south through Utah and Colorado to Arizona and New Mexico. It grows at high altitudes from 6,000 to 10,000 feet in altitude, though unlike Engelmann Spruce in the same area, it does not reach the alpine tree-line. It is most commonly found growing along stream sides in mountain valleys, where moisture levels in the soil are greater than the often low rainfall in the area would suggest.
It is a medium-sized evergreen tree growing to 80 to 100 feet tall, and sometimes as much as 150 feet tall, and with a trunk diameter of up to 59 inches around. The bark is thin and scaly, flaking off in small circular plates. The crown is conic in young trees, becoming cylindrical in older trees. The leaves are needle-like, 0.6 to 1.2 inches long, stout, rhombic in cross-section, dull gray-green to bright greenish-blue, with several lines of stomata.
The cones are pendulous, slender cylindrical, 2.33 to 4.33 inches long and 0.75 inches broad when closed, opening to 1.55 inches broad. They have thin, flexible scales, with a wavy margin. They are reddish to violet, maturing pale brown 5-7 months after pollination. The seeds are black with a slender, pale brown wing.
Blue Spruce is one of the most popular garden conifers, grown for its strongly greenish-blue foliage. Numerous cultivars selected for particularly bright blue foliage have been selected by the horticultural trade, some of them also slow-growing dwarf forms suitable for planting in small gardens. It is also sometimes used as a Christmas tree, though the very sharp needles make it a poor choice for families with children.
Blue Spruce trees are often used by homeowners and landscape architects for home security purposes. The sharp needles may deter unauthorized persons from entering private properties, and may prevent break-ins if planted under windows and near drainpipes. The aesthetic characteristics of the Blue Spruce, in conjunction with its home security qualities, make it a considerable alternative to artificial fences and walls.
The National Christmas Tree in Washington, D.C. is a Blue Spruce planted on the Ellipse in 1978. Blue Spruce is the State Tree of Colorado and Utah.