A deciduous tree, sometimes 30 or more ft high, usually 15 to 20 ft, with rather erect branches. Young wood at first green, becoming reddish brown and, when older, beautifully striped with white jagged lines. Leaves up to 7 in. long, a little less wide, with three conspicuous, tapering, forward-pointing lobes at the terminal part; margins finely and sharply double-toothed; lower surface covered with minute reddish down when young, which mostly wears off towards the end of the season; stalks 11⁄2 to 2 in. long, the enlarged bases of each pair clasping the shoot. Flowers yellow, produced in May on slender, pendulous racemes 4 to 6 in. long; each flower is 1⁄3 in. diameter, and borne on a stalk 1⁄4 to 1⁄2 in. long. Fruit in pendent racemes, glabrous; wings 3⁄4 in. long, each pair forming a crescent 11⁄2 to 2 in. across.
Native of eastern N. America; introduced in 1755. This maple is remarkable chiefly for the exceedingly handsome striping of its younger branches and stem. For a long time it was the only species known in cultivation with this character, but during the past eighty years or so several species have been introduced from Japan and China showing the same colouring, of which A. rufinerve, capillipes, and davidii are the best known. These and certain other species are placed in the section Macrantha, in which the characteristic snake-bark is associated with other distinctive botanical characters, notably the racemose inflorescence. It is most likely to be confused with A. rufinerve (q.v. for the marks of difference).
A. pensylvanicum is not so common in gardens as it was before the introduction of its Asiatic allies but still very worthy of cultivation. The leaves, large and handsome at maturity, have a pinkish tinge on opening, and usually turn yellow in autumn. It remains one of the most distinct and desirable of maples. It has been planted along two rides in the Forestry Commission's plantations at Alice Holt, Surrey, and thrives very well there; although only twelve years planted, some are over 20 ft tall.
cv. 'Erythrocladum'. – In this variety the young shoot turns a bright crimson after the fall of the leaf. This, added to the other attractions of the species, makes this variety one of the most attractive of small hardy trees. There are examples at Knightshayes Court, Devon, and Maidwell Hall, Northants. Put into commerce by Späth's nurseries, Berlin, in 1904.
From the Supplement (Vol. V)
A. 'Silver Vein'. – A hybrid between A. pensylvanicum 'Erythrocladum' (seed parent) and Forrest's form of A. davidii (at the time of the cross erroneously labelled A. laxiflorum), which was raised at the Chandlers Ford nursery of Messrs Hillier from a cross made in 1961 by Peter Douwsma of Australia, then working in the nursery. It is chiefly remarkable for the very conspicuous silver striations of its bark, which persist for a long time even on the lower part of the trunk. Habit spreading as in A. davidii; leaves three-lobed as in the seed parent (Roy Lancaster, The Plantsman, Vol. 1, p. 68 (1979)).