Leaves ovate to elliptic or lanceolate, acute or acuminate, cuneate or rounded at base, sharply serrate with appressed glandular teeth, and often slightly 3-lobed, when they unfold pubescent on the lower and puberulous on the upper surface, at maturity thick and firm, dark green and glabrous above, pale and pubescent or glabrous below, 1′—4′ long, ½′—1½′ wide, with a prominent midrib and primary veins and conspicuous reticulate veinlets; before falling in the autumn turning bright orange and scarlet; petioles stout, rigid, pubescent, 1′—1½′ in length; stipules narrowly lanceolate, acute, ½′—¾′ long; leaves at the end of vigorous shoots ovate to obovate, acuminate, often 3-lobed above the middle, rounded or cuneate at base, 2½′—3½′ long and wide, with petioles often 2′ in length. Flowers ¾′ in diameter on slender pubescent or glabrous pedicels, ½′—¾′ long, in short many-flowered clusters; calyx-tube deciduous from the mature fruit, glabrous, puberulous or tomentose, the lobes rather longer than the tube, minutely apiculate, glabrous or tomentose, hoary-tomentose on the inner surface; petals orbicular to obovate, erose or undulate on the margins, abruptly contracted into a short claw, ¼′ wide, white or rose color; styles 2—4, glabrous. Fruit obovoid-oblong, ½′—¾′ long, yellow-green, light yellow flushed with red or sometimes nearly red; flesh thin and dry.
A tree, 30°—40° high, with a trunk 12′—18′ in diameter, and slender branchlets coated at first with long pale hairs soon deciduous or persistent until the autumn, becoming bright red and lustrous, and later dark brown, and marked by minute remote pale lenticels; often a shrub with numerous slender stems. Winter-buds 1/16′ long, chestnut-brown, the inner scales at maturity lanceolate, usually bright red, and nearly ½′ in length. Bark ¼′ thick, and covered by large thin loose light red-brown plate-like scales. Wood heavy, hard, close-grained, light brown tinged with red, with lighter colored sapwood of 20—30 layers of annual growth; used for mallets, mauls, the handles of tools, and the bearings of machinery. The fruit has a pleasant subacid flavor.
Distribution. Deep rich soil in the neighborhood of streams, often forming almost impenetrable thickets of considerable extent; Aleutian Islands southward along the coast and islands of Alaska and British Columbia to Sonoma and Plumas Counties, California; of its largest size in the valleys of western Washington and Oregon.
Occasionally cultivated as an ornamental plant in the eastern states, and in western Europe.
× Malus Dawsoniana Rehd., a hybrid of Malus fusca and a form of M. pumila, has been raised at the Arnold Arboretum from seeds collected in Oregon.
4. SORBUS L. Mountain Ash.
Trees or shrubs, with smooth aromatic bark, stout terete branchlets, large buds covered by imbricated scales, the inner accrescent and marking the base of the branchlet by conspicuous ring-like scars, and fibrous roots. Leaves alternate, pinnate in the American species, the pinnæ conduplicate in the bud, serrate, deciduous; stipules free from the petioles, foliaceous. Flowers in broad terminal leafy cymes; calyx-tube urn-shaped, 5-lobed, the lobes imbricated in the bud, persistent; petals rounded, abruptly narrowed below, white; stamens usually 20 in 3 series, those of the outer series opposite the petals; carpels 2—5, usually 3; styles usually 3, distinct; ovules 2 in each cell, ascending; raphe dorsal; micropyle inferior. Fruit a small subglobose red or orange-red pome with acid flesh, and papery carpels free at the apex. Seeds 2, or by abortion 1, in each cell, ovoid, acute, erect; seed-coat cartilaginous, chestnut-brown and lustrous; embryo erect; cotyledons plano-convex, flat; radicle short, inferior.
Sorbus is widely distributed through the northern and elevated regions of the northern hemisphere with three or four species in North America of which one is arborescent, and with many species in eastern Asia and in Europe. Of the exotic species, Sorbus Aucuparia L., the common European Mountain Ash, or Rowan-tree, with several of its varieties and hybrids, is often cultivated as an ornamental tree in Canada and the northern states and has become sparingly naturalized northward.
Sorbus is the classical name of the Pear or of the Service-tree.