白木乌桕 bai mu wu jiu

Stillingia japonica Siebold & Zuccarini, Abh. Math.-Phys. Cl. Königl. Bayer. Akad. Wiss. 4(2): 145. 1845; Excoecaria japonica (Siebold & Zuccarini) Müller Argoviensis; Sapium japonicum (Siebold & Zuccarini) Pax & K. Hoffmann; Shirakia japonica (Siebold & Zuccarini) Hurusawa; Triadica japonica (Siebold & Zuccarini) Baillon.

Treelets to 8 m tall, glabrous; branches slender, smooth, gray-brown. Stipules membranous, linear-lanceolate, ca. 1 cm; petiole 1.5-3 cm, bilateral flattened into attenuate winged shape, without glands; leaf blade ovate, ovate-rectangular, or elliptic, 7-16 × 4-8 cm, papery, base obtuse, truncate, or sometimes shallowly cordate, usually oblique, margin entire, sparsely glandular abaxially in upper half near margin, with 2 glands at base of midrib; midrib elevated abaxially, lateral veins 8-10 pairs. Inflorescences terminal, 4.5-11 cm, female flowers at base, male ones at upper part, or sometimes male throughout. Male flowers: pedicels 1-2 mm; bracts ovate to ovate-lanceolate, 2-2.5 × 1-1.2 mm, margins irregularly serrulate, basal glands ovoid, bracts 3- or 4-flowered; calyx cup-shaped, 3-lobed, lobes irregularly serrulate; stamens (2 or)3, usually exceeding calyx; anthers globose, slightly shorter than filaments. Female flowers: bracts 3-partite almost to base, lobes lanceolate, 2-3 mm, usually central ones larger, lateral lobes each 1-glandular; pedicels stout, 6-10 mm; calyx lobes 3, triangular, nearly as long as wide; ovary ovoid, smooth, 3-celled; styles connate at base; stigma 3, revolute. Capsules triangular-globose, 10-15 mm in diam.; columella deciduous. Seeds oblate, 6-9 mm in diam., with tawny maculate stripes. Fl. May-Jun, fr. Jul-Sep.

Moist forests; 100-400 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hunan, Hubei, Jiangsu, Jiangxi, Shandong, Sichuan, Zhejiang [Japan, Korea].

Initial observations suggest that the Chinese material of Neo-shirakia japonica can be divided into two forms, one of relatively limited distribution matching the type from Japan and the other more widespread differing in leaf shape and enlarged basal glands and probably representing a third species.