A tree 80 to 100, occasionally 150 ft high, assuming as a young tree in cultivation a pyramidal form, with slightly ascending branches; young shoots pale yellowish brown, clothed with stiff, erect down. Leaves arranged all round the twig, but thinly beneath; they are 3⁄4 to 11⁄8 in. long, quadrangular, bluntish at the tips, flexible, dull, slightly glaucous-green, with three or four lines of stomata on all four surfaces. Cones 11⁄2 to 3 in. long, 3⁄4 to 1 in. in diameter; tapered towards the top, pale shining brown when mature; scales with a truncate apex and jagged margins.
Native of the mountains of western N. America from Alberta and British Columbia (where it attains its greatest size), south to New Mexico and Arizona. This handsome spruce is very hardy, and thrives better in N. Continental Europe and New England, where the winters are severe, than it does in places with a mild climate and late spring frosts. It is comparatively rare in gardens, the tree grown under the name being frequently the glaucous form of P. pungens. The two species, although so much confused, are really very distinct. P. engelmannii is easily recognised by its downy shoots; its soft and flexible, not spine-tipped leaves; also by its shorter cones.
The finest specimens of P. engelmannii grow at Dawyck in Peeblesshire; they were collected as seedlings in the Rocky Mountains by F. R. S. Balfour in 1902 and the taller of the two measures 89 × 71⁄4 ft (1974).
f. glauca Beissn. – Leaves with a pronounced glaucous hue. There is an example at Dawyck, measuring 63 × 41⁄4 ft (1966). F. R. S. Balfour considered that this form would be more suitable for Scotland than the much commoner glaucous forms of P. pungens, which grow best in a hot, dry climate.