Leaves more or less cordate at the broad base, deeply 5-lobed by narrow sinuses acute in the bottom, the lobes acute or acuminate, the terminal lobe often 3-lobed, the others usually furnished with small lateral lobules, the lower lobes much smaller than the others, prominently 3—5-nerved, puberulous when they unfold, especially on the upper surface along the principal veins, and at maturity subcoriaceous, dark green and lustrous on the upper surface, pale on the lower surface, 8′—12′ in diameter; turning in the autumn bright orange color before falling; petioles stout, 10′—12′ in length, with enlarged bases united and encircling the stem and often furnished on the inside with small tufts of white hairs. Flowers bright yellow, fragrant, ¼′ long, on slender pubescent often branched pedicels ½′—¾′ in length, the staminate and pistillate together in graceful pendulous slightly puberulous racemes 4′—6′ long, appearing in April and May after the leaves are fully grown; sepals petaloid, obovate, obtuse and a little longer and broader than the spatulate petals; stamens 9—10, with long slender filaments hairy at base, exserted in the staminate flower and included in the pistillate flower, and orange-colored anthers; ovary hoary-tomentose, reduced in the staminate flower to a minute point; styles united at base only; stigmas long and exserted. Fruit fully grown by the 1st of July and ripening late in the autumn; nutlets covered with long pale hairs, their wings 1½′ long, ½′ wide, slightly divergent and glabrous with the exception of a few hairs on the thickened edge; seeds dark-colored, rugose and pitted, ¼′ long.
A tree, 80°—100° high, with a tall straight trunk 2°—3° in diameter, stout often pendulous branches forming a compact handsome head, and stout branchlets smooth and pale green at first, becoming bright green or dark red in their first winter, covered more or less thickly with small longitudinal white lenticels, and in their second summer gray or grayish brown. Winter-buds obtuse; terminal ¼′ long, with short broad slightly spreading dark red ciliate outer scales rounded on the back, those of the inner ranks green and foliaceous, and at maturity 1½′ long, colored and puberulous; axillary buds minute. Bark of the trunk ½′—¾′ thick, brown faintly tinged with red or bright reddish brown, deeply furrowed and broken on the surface into small square plate-like scales. Wood light, soft, not strong, close-grained, rich brown tinged with red, with thick lighter colored often nearly white sapwood of 60—80 layers of annual growth; more valuable than the wood produced by other deciduous-leaved trees of western North America, and in Washington and Oregon used in the interior finish of buildings, for furniture, and for axe and broom-handles.
Distribution. Banks of streams or on rich bottom-lands or the rocky slopes of mountain valleys; coast of Alaska south of latitude 55° north, southward along the islands and coast of British Columbia, through Washington and Oregon west of the Cascade Mountains, and southward along the coast ranges and the western slopes of the Sierra Nevada to the San Bernardino Mountains, and to Hot Spring Valley, San Diego County, California; on the Sierra Nevada usually between altitudes of 2000° and 5000° and on the southern mountains rarely above 3000°; most abundant and of its largest size in the humid climate and rich soil of the bottom-lands of southwestern Oregon, forming extensive forests; in California usually much smaller, especially on the coast ranges.
Generally planted in the Pacific States for shade and as a street tree, and occasionally in the Eastern States as far north as Long Island, New York, and in western Europe; not hardy in Massachusetts.
6. [Acer saccharum] Marsh. Sugar Maple. Rock Maple.
Leaves rarely in whorls of 3, heart-shaped by a broad sinus, truncate or sometimes cuneate at base, 3—5-lobed, the lobes usually acute sparingly sinuate-toothed usually 3-lobulate at apex, with 3—5 conspicuous nerves, and reticulate veinlets, when they unfold coated below with pale pubescence, glabrous or more or less pubescent on the nerves below (var. Schneckii Rehd.) and at maturity, 4′—5′ in diameter, often rather coriaceous, dark green and opaque on the upper surface, green or pale (var. glabrum Sarg.) on the lower surface; turning in the autumn brilliant shades of deep red, scarlet and orange or clear yellow; petioles slender, glabrous, 1½—3′ in length. Flowers appearing with the leaves on slender more or less hairy pedicels ¾′—3′ long, in nearly sessile umbel-like corymbs from terminal leaf-buds and lateral leafless buds, the staminate and pistillate in the same or in separate clusters on the same or on different trees; calyx broad-campanulate, 5-lobed by the partial union of the obtuse sepals, greenish yellow, hairy on the outer surface; corolla 0; stamens 7—8, with slender glabrous filaments twice as long as the calyx in the staminate flower and much shorter in the pistillate flower; ovary obtusely lobed, pale green, covered with long scattered hairs, in the staminate flower reduced to a minute point; styles united at base only, with 2 long exserted stigmatic lobes. Fruit ripening in the autumn, glabrous, with broad thin and usually divergent wings ½′—1′ long; seeds smooth, bright red-brown, ¼′ long.
A tree, 100°—120° high, with a trunk often 3°—4° in diameter, rising sometimes in the forest to the height of 60°—70° without branches, or in open situations developing 8°—10° from the ground stout upright branches forming while the tree is young a narrow egg-shaped head, ultimately spreading into a broad round-topped dome often 70°—80° across, and slender glabrous branchlets green at first, becoming reddish brown by the end of their first season, lustrous, marked by numerous large pale oblong lenticels, and in their second winter pale brown tinged with red. Winter-buds acute, ¼′ long, with purple slightly puberulous outer scales, and inner scales becoming 1½′ long, narrow-obovate, short-pointed at apex, thin, pubescent, and bright canary yellow. Bark of young stems and of large branches pale, smooth or slightly fissured, becoming on large trunks ½′—¾′ thick and broken into deep longitudinal furrows, the light gray-brown surface separating into small plate-like scales. Wood heavy, hard, strong, close-grained, tough, light brown tinged with red, with thin sapwood of 30-40 layers of annual growth; largely used for the interior finish of buildings, especially for floors, in the manufacture of furniture, in turnery, shipbuilding, for shoe-lasts and pegs, and largely as fuel. Accidental forms with the grain curled and contorted, known as curly maple and bird’s-eye maple, are common and are highly prized in cabinet-making. The ashes of the wood are rich in alkali and yield large quantities of potash. Maple sugar is principally made from the sap of this tree.
Distribution. Newfoundland and Nova Scotia, westward to the Lake of the Woods, Ontario, and southward through eastern Canada and the northern states, and along the Appalachian Mountains to northern Georgia; in central Alabama and Mississippi, and westward in the United States to Minnesota, northeastern South Dakota (coulées of Little Minnesota River, Roberts County), central and northwestern Iowa, eastern Kansas, central Oklahoma, and eastern Louisiana; most abundant northward; ascending in North Carolina the Alleghany Mountains to altitudes of 3000°; the var. glabrum rare and local in the north from Prince Edwards Island and Lake St. John, Quebec, to Iowa and southward to Pennsylvania, Ohio and central Tennessee; more abundant southward; apparently the only form but not common in South Carolina, Alabama, Mississippi, Louisiana and southern Arkansas; the var. Schneckii with leaves glaucous or glaucescent below and more or less densely pubescent with spreading hairs, on the under side of the midrib and veins and on the petioles, southern Indiana and Illinois to western Kentucky and western and middle Tennessee, northwestern Georgia (near Rome, Floyd County), and to eastern Missouri southward to Williamsville, Wayne County.