Sargent's rowan

Description

Sorbus sargentiana, Sargent's rowan is a species of flowering plant in the family Rosaceae, native to southwestern Sichuan and northern Yunnan in China, where it grows at altitudes of 2,000–3,200 m (6,560–10,500 ft). It is a small to medium-sized deciduous tree growing to 6–16 m (20–52 ft) tall, with a trunk up to 50 cm (20 in) in diameter, and a rounded crown. The bark is dark grey, and the shoots very stout, with large (1–2 cm), dark red, sticky resinous winter buds. The leaves are the largest of any rowan, dark green with impressed veining above, glaucous beneath, 20–35 cm (8–14 in) long and 15–20 cm (6–8 in) broad, with persistent 1 cm broad stipules. The pinnate leaves consist of 9–11 oblong-lanceolate leaflets 5–14 cm (2–6 in) cm long and 3.5–5 cm (1–2 in) broad, with an acute apex, serrated margins. The basal leaflets are slightly smaller than the apical leaflets. They change to a rich orange-pink to purple or dark red in mid-autumn (fall). The flowers are 5–7 mm in diameter, with five white petals and 20 yellowish-white stamens; they are produced 200–500 together in very large corymbs 12–25 cm (5–10 in) in diameter, in late spring to early summer. The fruit is a pome 5–8 mm diameter, bright orange-red to red, maturing in early autumn; it is juicy, and readily eaten as soon as it is ripe by thrushes, which disperse the seeds. It is grown as an ornamental tree for its bold foliage, huge clusters of fruit, and bright autumn colour. It has gained the Royal Horticultural Society's Award of Garden Merit. Sorbus is a genus of over 100 species of trees and shrubs in the rose family, Rosaceae. Species of Sorbus are commonly known as whitebeam, rowan (mountain-ash) and service tree. The exact number of species is disputed depending on the circumscription of the genus, and also due to the number of apomictic microspecies, which some treat as distinct species, but others group in a smaller number of variable species. Recent treatments classify Sorbus in a narrower sense to include only the pinnate leaved species of subgenus Sorbus, raising several of the other subgenera to generic rank. Sorbus is not closely related to the true ash trees which belong to the genus Fraxinus, although the leaves are superficially similar.