The red spruce is a close ally of P. mariana, but appears to be extremely uncommon in cultivation. It is, apparently, on the average a considerably larger tree than P. mariana, being usually 70 to 80 ft high; it has similar although less persistently downy young shoots. The leaves are quadrangular, 1⁄2 to 3⁄4 in. long, with stomatic lines on all four surfaces; they differ from those of P. mariana in being of a dark yellowish, rather than glaucous, green, and somewhat more slender. Cones reddish brown, up to 2 in. long and thus larger than those of P. mariana; the scales, too, are entire, or only slightly toothed at the apex. But the most marked distinction between the two is in the duration of the cones on the branches. In P. rubens they begin to fall as soon as the scales open, but in P. mariana they persist sometimes twenty or thirty years. In the wild P. rubens has a much more restricted distribution than P. mariana, being confined to eastern N. America, where it extends from Prince Edward Island southward to the mountains of N. Carolina. Introduced in 1755. It has not much to recommend it for gardens beyond its interest. Bot. Mag., t. 9446.
The oldest known examples of P. rubens grow in the Rhinefield Drive near Lyndhurst in the New Forest; they were planted in 1861 and the best measures 83 × 53⁄4 ft (1971). Others are: National Pinetum, Bedgebury, Kent, pl. 1925, 50 × 41⁄4 ft (1970), and several others slightly smaller; Wakehurst Place, Sussex, 59 × 33⁄4 ft (1970); Bicton, Devon, 60 × 4 ft (1968).