深灰枫 shen hui feng

Acer caesium subsp. giraldii (Pax) A. E. Murray; A. giraldii Pax.

Trees to 25 m tall, andromonoecious. Bark gray. Branchlets glabrous, usually glaucous; winter buds ovoid, margin ciliate. Leaves deciduous; petiole purplish green, 10-15 cm, glabrous; leaf blade abaxially glaucous, adaxially green, 11-21 × 11-14 cm, papery, lateral veins 7-9 pairs, distinct abaxially, base cordate, 5-lobed, rarely 3-lobed; lobes triangular, 1-1.5 cm, margin serrulate, apex acuminate. Inflorescence terminal, corymbose; peduncles ca. 6 cm. Sepals 5, yellowish green, ca. 5 × 3 mm. Petals 5, white, oblanceolate, ca. 5 × 1.5 mm. Stamens 8, 3-5 mm. Disk glabrous, extrastaminal. Ovary pubescent. Fruit yellowish; nutlets convex, ca. 8 mm in diam.; wing including nutlet 4-5.5 cm, wings spreading erectly. Fl. May-Jun, fr. Sep. 2n = 26, 52.

Alpine forests; 2000-3700 m. SE Gansu, SW Henan, W Hubei, Ningxia, S Shaanxi, Sichuan, SE Xizang, NW Yunnan [N India, Nepal, Pakistan].

One of us (de Jong) prefers to distinguish Acer caesium subsp. giraldii by its thicker branchlets and conspicuous, glaucous-white winter color, with leaves somewhat smaller, mainly 3-lobed; it appears to be a good taxon, comparable with A. sterculiaceum subsp. franchetii as a northern taxon of A. sterculiaceum.