Flower:

Male and female flowers are cone like structures called strobili, both borne on the same tree at or near the tips of one year old branches. Males are initially reddish purple becoming yellowish-brown. Females are erect and purple.

Leaves and stems:

Leaves are needle-like, dark green to light silvery blue, single in a close spiral up the branch, ¾ to 1½ inch long, squarish in cross section, stiff, the tip sharply pointed and very prickly to the touch. The needles typically persist 2 to 3 years in Minnesota.

Twigs are orangish to light brown, smooth, turning grayish brown after several seasons with the fallen needles leaving raised roughish leaf scars.

The bark is thin and gray or brownish with flaky scales, older bark can become furrowed. Trunks are typically 12 to 18 inches diameter at breast height (dbh) in Minnesota landscapes.

Fruit:

Fruit is an oblong cone, 2 to 4 inches long, straw-colored to light brown, the scales thin and papery with wavy edging and fringed with small, irregular teeth at the tip.

Notes:

Colorado spruce is native to the mountains of the southwestern US and, while heavily planted in both urban and rural landscapes across Minnesota, it has never been documented naturalized. Much of its appeal is due to its distinctive bright blue needles, though seed populations can also range into the dark greens. In spite of its popularity, it is not well adapted to Minnesota's warm, humid summers and mature trees suffer from several disfiguring diseases. Cytospora canker is a bacterial disease that attacks the vascular system, causing dieback of branches and is often accompanied by excessive sap bleeding. Rhizosphaera and Stigmina needlecast are fungi that infect the needles causing premature needle drop that are responsible for the rapid thinning and loss of lower branches. Colorado spruce is readily identifiable by its stiff, very prickly needles and the large cones with a fringed tip on the papery scales.