2. Platanus acerifolia (Aiton) Willdenow, Sp. Pl. 1: 474. 1797.
二球悬铃木 er qiu xuan ling mu
Platanus orientalis Linnaeus var. acerifolia Aiton, Hort. Kew. 3: 364. 1789; P. hybrida Brotero.
Trees deciduous, to 30 m tall. Young branchlets densely gray-yellow tomentose, old ones red-brown, glabrous. Stipules 1–1.5 cm; petiole 3–10 cm, densely yellow-brown pubescent; leaf blade broadly ovate, 12–25 × 10–24 cm, (3 or)5(or 7)-lobed, gray-yellow pubescent on both surfaces when young, glabrate and then pubescent only at vein axils abaxially, principal veins 3(or 5), arising from base or lateral 2(or 4) from midvein above base, base subcordate or truncate; lobes entire or coarsely 1- or 2-dentate at margin; central lobe broadly triangular, as long as wide. Flowers usually 4-merous. Male flowers: sepals ovate, pubescent; petals oblong, ca. 2 × as long as sepals; stamens longer than petals; anther connective peltate, pubescent. Fruiting branchlets with (1 or)2(or 3) infructescences. Infructescence capitate, ca. 2.5 cm in diam. Achenes with persistent style spiniform, 2–3 mm; basal hairs absent or very short, not exserted from infructescence. Fl. Mar–May, fr. Jun–Oct.
Cultivated in C, NE, and S China [of cultivated origin in SW Asia or Europe].
This widely planted tree is either a hybrid between Platanus occidentalis and P. orientalis or a cultivar of P. orientalis; the origin has been much discussed but remains uncertain.