川滇花楸 chuan dian hua qiu

Shrubs or small trees, 4–6 m tall. Branchlets reddish brown to grayish brown when young, dark blackish gray when old, terete, densely rust-brown pubescent when young, gradually glabrescent; buds ovoid, 4–7 mm, apex shortly acuminate or acute; scales several, brown, rust-brown pubescent. Leaves imparipinnate, together with rachis 10–18 cm; petiole 1.2–2 cm; stipules caducous, subulate, 3–6 mm, membranous; rachis abaxially rust-brown pubescent, slightly winged, sulcate adaxially; leaflet blades 9–13-paired, at intervals of 6–12 mm, grayish green abaxially, oblong or oblong-elliptic, 1.5–2.5 × 6–10 mm, abaxially rust-brown pubescent along midvein, adaxially glabrous, base broadly cuneate or rounded, margin sparsely serrate apically, with 5–10 minute sharp teeth per side, usually entire basally, apex acute. Compound corymbs 5–7 × 2–5 cm, many flowered; rachis and pedicels rust-brown pubescent. Pedicel 1.5–3 mm. Hypanthium campanulate, rusty brown pubescent. Sepals triangular-ovate, 1–2 mm, apex ± obtuse. Petals white, ovate or subrounded, 3–3.5 × 2.5–3 mm, adaxially puberulous, apex obtuse. Stamens 20, ca. 1/2 as long as petals. Styles 5, slightly shorter or nearly as long as stamens, glabrous. Fruit pink, globose, 7–8 mm in diam.; sepals persistent. Fl. Jun–Jul, fr. Sep–Oct. 2n = 34*, 68*.

Mountain slopes, roadsides, mixed forests along river banks, grasslands, bamboo thickets; 2800--4400 m. SW Sichuan, SE Xizang, NW Yunnan.

The type specimen is from an apomictic microspecies known only in cultivation, but almost indistinguishable specimens are diploid and frequent in the wild. In Sichuan, SE Xizang, and Yunnan there are similar apomictic microspecies with nearly identical fruits but larger leaflets. These are probably of hybrid origin with one parent being Sorbus vilmorinii and the other S. rehderiana or S. monbeigii. These trees have leaves 13–23(–40) cm, with 9–18 pairs of leaflets to 37(–75) × 15(–17) mm.