Sorbus sargentiana Koehne

A tree said to grow to 50 ft high in the wild; young growths stout, grey-brown or fawn by winter, about 1⁄2 in. thick, downy at first; winter-buds not unlike those of a horse-chestnut, ovoid, up to 7⁄8 in. long and 1⁄2 in. wide, often so densely varnished that the scales are scarcely distinguishable. Leaves pinnate, up to 12 in. or slightly more long (including petiole 2 to 3 in. long), with four to six pairs of leaflets; rachis red on the exposed side, slightly woolly at first beneath, narrowly grooved. Leaflets oblong-lanceolate, acuminately tapered to a sharp apex, up to 5 in. long and 13⁄4 in. broad, with very numerous closely set pairs of lateral veins (mostly twenty to twenty-five pairs), impressed above, prominent beneath, upper surface light green, the lower whitish and thinly downy, margins finely serrated except in the lower quarter. Stipules very large and leafy, persistent, broadly obovate-kidney-shaped, coarsely toothed, present both on extension growths and in the inflorescence. Flowers borne in early June, individually small (about 1⁄4 in. wide) but crowded in flattish, white-hairy inflorescences up to 10 in. wide. Petals fugitive, orbicular. Styles three or four. Fruits flattened-globose, about 5⁄16 in. wide, matt orange-scarlet, in flattish more or less circular clusters, up to 500 or even more in each.

A native of W. Szechwan, China, described from specimens collected by Wilson in 1908 and 1910 for the Arnold Arboretum, after whose then Director it is named. It was also introduced by Wilson, and the plants cultivated in Britain probably derive from his 1910 collection in the Mupin area (W.4207). All things considered, S. sargentiana is the finest of the rowan group and was awarded a First Class Certificate in 1956. The handsome leaves, with larger leaflets than in any other species except S. insignis, are mahogany-coloured when they unfold in late May, and colour brilliantly – usually orange-red – in early November. The display of fruits is truly spectacular, but cannot be fully appreciated unless the tree is given a prominent position in nearly full sun. Even in winter it is a striking sight, with its large, richly coloured buds, some so glutinous that they seem to be encased in aspic. Its only fault is the stiff, open and sparsely branched habit. The heavily scarred spurs are a remarkable feature; they may remain on the tree for twenty years or more, gaining a few inches in length each season. Young grafted plants are sometimes so well spurred that they look like well pruned cordon-apples and may fruit to excess without making extension growths. These can be induced, however, by removing the terminal buds from some of the spurs to encourage the lateral buds to grow out.

Perhaps the finest examples of S. sargentiana in Britain are the fine pair at Westonbirt in Gloucestershire, in Broad Drive. They measure 34 × 43⁄4 ft and 39 × 31⁄4 ft (1974).

From the Supplement (Vol. V)

specimens: Valley Gardens, Windsor Great Park, 28 × 23⁄4 ft (1981); Westonbirt, Glos., the larger tree is dead and the other measures 42 × 33⁄4 ft below graft union at 3 ft (1982); Trewithen, Cornwall, 30 × 51⁄4 ft below union (1985); Keir House, Perths., 33 × 31⁄4 ft (1985); Rowallane, Co. Down, 30 × 43⁄4 ft at 2 ft (1976).