12. Acer pictum Thunberg in Murray, Syst. Veg., ed. 14. 912. 1784.
色木枫 se mu feng
Trees to 20 m tall, andromonoecious. Bark gray. Branchlets slender, glabrous; winter buds subglobose, scales 4 pairs. Leaves deciduous; petiole 4-6 cm, slender, glabrous; leaf blade abaxially pale green, adaxially dark green, oblong, (8-)9-11(-12) × (4-)6-8(-12) cm, papery, abaxially glabrous except for yellowish or whitish hairs on veins or at vein axils, sometimes abaxially pubescent, adaxially glabrous, base truncate, subtruncate, or hastate, 3-, 5-, 7-, or 9-lobed; lobes triangular or ovate, margin entire, apex acuminate or subcaudate-acuminate. Inflorescence terminal, paniculate-corymbose, ca. 4 × 4 cm, glabrous, numerous flowered; peduncles 1-2 cm. Pedicel ca. 1 cm, glabrous. Sepals 5, greenish yellow, oblong, 2-8 mm, ciliate, apex obtuse. Petals 5, whitish, elliptic or elliptic-obovate, ca. 3 mm. Stamens 8, shorter than petals, glabrous. Ovary glabrous or glabrescent, rudimentary in staminate flowers; style very short, glabrous; stigmas revolute. Fruit yellowish when mature; nutlets flat, compressed, 1-1.3 cm × 8-10 mm; wing oblong, including nutlet 3-3.5 × 1-1.5 cm, wings spreading variously. Fl. Apr-May, fr. Sep. 2n = 26.
Forests, usually in valleys, also cultivated; sea level to 3300 m. Anhui, Gansu, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jilin, Liaoning, Nei Mongol, Shaanxi, Shanxi, Sichuan, SE Xizang, Yunnan, Zhejiang [Japan, Korea, Mongolia, E Russia].
One of us (Chang) believes that Acer pictum subsp. macropterum, subsp. mono, subsp. pictum, subsp. pubigerum, and subsp. tricuspis so closely resemble each other that they may be taken for one variable and widely distributed taxon. However, one of us (Chen) believes that some of the subspecies are good and differ in their distributions; while awaiting future results about their status, it is best to retain their subspecific status. de Jong notes that A. pictum is a very complex species requiring further study.