Blue spruce

Picea pungens
Foliage and young cones
Conservation status
Least Concern  (IUCN 2.3)
Scientific classification
Kingdom:	Plantae
Division:	Pinophyta
Class:	Pinopsida
Order:	Pinales
Family:	Pinaceae
Genus:	Picea
Species:	P. pungens
Binomial name
Picea pungens Engelm.

Picea pungens (Colorado Blue Spruce or Blue Spruce) 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 1,750-3,000 m altitude, though unlike Engelmann Spruce in the same area, it does not reach the alpine tree-line. It is most commonly found growing along streamsides in mountain valleys, where moisture levels in the soil are greater than the often low rainfall in the area would suggest.

Mature cone

Immature cone

It is a medium-sized evergreen tree growing to 25-30 m tall, exceptionally to 46 m tall, and with a trunk diameter of up to 1.5 m. The bark is thin and scaly, flaking off in small circular plates 5-10 cm across. The crown is conic in young trees, becoming cylindric in older trees. The shoots are stout, orange-brown, usually glabrous, and with prominent pulvini. The leaves are needle-like, 15-30 mm long, stout, rhombic in cross-section, dull gray-green to bright glaucous blue (very variable from tree to tree in wild populations), with several lines of stomata; the tip is viciously sharp.

The cones are pendulous, slender cylindrical, 6-11 cm long and 2 cm broad when closed, opening to 4 cm broad. They have thin, flexible scales 20-24 mm long, with a wavy margin. They are reddish to violet, maturing pale brown 5-7 months after pollination. The seeds are black, 3-4 mm long, with a slender, 10-13 mm long pale brown wing.

Blue Spruce does not normally hybridize with other spruces, though hybrids with Engelmann Spruce have been found very rarely.

The tree in the center of the The Ellipse in Washington DC is a Colorado Blue Spruce.