Sorbus erythrosepala Kainul., Sjöman, Aldén, 2023

Kainulainen, Kent, Sjöman, Henrik & Aldén, Björn, 2023, Sorbus erythrosepala Kainul., Sjöman, Aldén, sp. nov. (Rosaceae), a new rowan from Yunnan, China, Adansonia (3) 45 (21), pp. 337-342 : 338

Sorbus erythrosepala Kainul., Sjöman, Aldén , sp. nov.

( Figs 1C ; 2 ; 3 )

Sorbus erythrosepala sp. nov. is morphologically similar to S. filipes Hand. -Mazz. in having lax inflorescences with pink flowers; longpedunculate and ± pendulous infructescences and white to pink fruits, but it differs from the latter in having leaves that are sparsely pubescent and dull (vs glabrous and glossy), and leaflets that are longer (to c. 35 mm vs c. 20 mm) and more numerous (up to 15 vs 8-13). Furthermore, its mature fruits are usually white (sometimes with pink blotches and usually with pink to crimson calyx lobes) whereas fruits of Sorbus filipes are usually pinkish.

TYPE SPECIMEN. — China. Yunnan, Diqing Prefecture, mountain above Napa Hai , 27°55’N, 99°34’E, 3600 m alt., degraded Pinus densata forest with bamboo, 15.IX.1993 (fr.) , B. Aldén , M. Lidén , L. R. Fu , S. Z. Yun, and H. Zetterlund KGB 71 (holo-, GB [GB-0209594]!) . ETYMOLOGY. — The specific epithet refers to the red sepals, which are distinctly contrasting on the otherwise white fruits.

DESCRIPTION

Shrub, to 2.5 m tall. Branchlets pubescent when young, glabrous when old. Bark brown to dark grey with pale yellow lenticels. Buds ovoid, brownish red, ± glossy, yellowish brown pubescent. Leaves pinnately compound, together with rachis 12-22 × 4.5-7 cm; petiole 1.5-2.5 cm long; stipules persistent, ovate, furcate, c. 5 × 3 mm; rachis slightly winged, sulcate, sparsely pubescent; leaflets 8-15 pairs, opposite, oblong to oblong-ovate, 1.5-3.5 × 0.7-1.5 cm, surfaces sparsely pubescent, dull green adaxially, pale greyish-green abaxially; lateral veins 8-10 pairs, margins serrate; base ± oblique, cuneate to rounded, apex acute to rounded. Inflorescences corymbose, 3-30 flowered, pedicels sparsely pubescent. Flowers 10-15 mm in diam.; hypanthium campanulate, reddish pink, glabrous; sepals brownish pink (apex greenish), fleshy, broadly triangular, 2-3 × 3-4 mm, margins entire, abaxially glabrous, adaxially rufous pubescent towards apex; petals pink with reddish venation, ± glabrous, orbiculate to obovate, 5-6 × 5-6 mm, incurved at anthesis; stamens 12-20; carpels entirely adnate to hypanthium, styles 3-5, c. as long as stamens, puberulous basally. Fruits subglobose, 12-16 mm in diam., glabrous, soft, white (sometimes with pink blotches and usually with pink to crimson sepals), sepals persistent and incurved on fruits. Mesocarp white. Seeds brown, striate, flattened, ± obovate, the tapering (hilar) end being curved, 4-5 × 2-3 mm.

Figures

FIG. 1. — Sorbus species collected during the KGB-expedition to Yunnan: A, Sorbus filipes Hand.-Mazz. (KGB 555, 1993-10-02, Bei Ma Shan); B, S. macrantha Merr. (KGB 552, 1993-10-02, Bei Ma Shan); C, S. erythrosepala sp. nov. (KGB 71, 1993-09-15, Napa Hai). Photographs: B. Aldén.

FIG. 2. — Holotype of Sorbus erythrosepala sp. nov. (GB-0209594), reproduced with permission from Herbarium GB.

FIG. 3. — Sorbus erythrosepala sp. nov., photos of cultivated material (KGB 71) at Gothenburg Botanical Garden:A, flower buds; B, open flowers;C, branch with immature fruits; D, ripe fruits; E, buds; F, shrub in autumn colours with pendulous infructescenses. Photographs: K. Kainulainen.