P. nìgra.
1. Pìcea nìgra, Link. (Black or Double Spruce.) Leaves about ½ in. long, erect, stiff, somewhat 4-sided, very dark green or whitish-gray; branchlets pubescent. Cones persistent, 1 to 1½ in. long, ovate or ovate-oblong, changing from dark purple to dull reddish-brown; scales very thin, roundish, with toothed or uneven edges. A conical-shaped tree, 40 to 80 ft. high; wild in the North and along the Alleghanies; often cultivated. Bark dark brown; branches horizontal; wood light reddish.
Var. rubra has larger, darker leaves, and larger, brighter-colored cones.
P. álba.
2. Pìcea álba, Link. (White or Single Spruce.) Leaves ½ to ¾ in. long, rather slender, needle-shaped, sharp-pointed, incurved, pale- or glaucous-green; branchlets smooth. Cones deciduous, 2 in. long, oblong-cylindrical, with entire, thin-edged scales. Tree 25 to 100 ft. high, of beautiful, compact, symmetrical growth when young, and such light-colored foliage as to make it a fine species for cultivation. Wild in the North, and cultivated throughout. There are varieties with bluish-green (var. cærulea) and with golden (var. aurea) foliage in cultivation.
P. excélsa.
3. Pìcea excélsa, Link. (Norway Spruce.) Leaves ¾ to 1 in. long, rigid, curved, dark green. Cones 5 to 7 in. long, and pendent at maturity, with the scales slightly incurved. A large tree, 70 to 120 ft. high, of vigorous growth, with numerous, stout, drooping branches; abundant in cultivation. A score of named varieties are sold at the nurseries, some quite dwarf, others so very irregular in shape as to be grotesque.
