PTEROCARPUS Jacquin, Sel. Stirp. Amer. Hist. 283. 1763, nom. cons. [Draft]

紫檀属  zi tan shu

Zhang Dianxiang; Kai Larsen

Tall trees, mostly deciduous. Branches spreading, glabrous to pubescent. Leaves alternate, imparipinnate, stipulate; leaflets 5 or more, rarely 3, mostly alternate, rarely subopposite, estipellate, leathery, glabrous to pubescent, base narrow to rounded, margin entire, apex retuse to acuminate. Inflorescence a simple raceme to a lax, terminal or axillary panicle. Pedicel articulate. Flowers yellow; bract and bracteoles minute, caducous. Calyx often incurved, turbinate, 5-toothed; teeth short, upper 2 ± connate. Corolla papilionaceous, vexillum ovate to orbicular, distinctly clawed, crisped; wings and keels obliquely oblong to oblong, clawed. Stamens 10, monadelphous to diadelphous (5+5 or 9+1), staminal sheath split open dorsally; anthers versatile. Ovary shortly stipitate; ovules 2–6; style incurved, glabrous; stigma terminal. Pod indehiscent, ovoid to orbicular; persistent style turned laterally; 1- or 2-seeded.

About 30 species: pantropical with the exception of Australia, with the greatest diversity in Africa.

1. Pterocarpus indicus Willdenow, Sp. Pl. 3: 904. 1802.

紫檀  zi tan

[??add Pterocarpus wallichii Wight & Arnott; P. zollingeri Miquel].

Trees to 15–25 m tall. Branches spreading. Leaves alternate, imparipinnate, 15–30 cm, stipulate; stipules early caducous; leaflets 5–7, rarely 9–11, alternate, occassionally subopposite; petiolules 4–7 mm; rachis and petiolule glabrous; blade ovate-elliptic, 5–11 × 3.5–5.5 cm, thinly papery, glabrous, lateral veins 6-8 pairs, base truncate, margin entire, apex shortly blunt-acuminate. Inflorescence a raceme or panicle, mostly axillary, rarely terminal, 10–18 cm, puberulous. Pedicel slender, 7–9 mm, slender, jointed. Flowers yellow, 1–1.5 cm; bract small; bracteoles 2, linear-oblong, at base of calyx. Calyx turbinate, 4–6 mm, distinctly 5-toothed; teeth rounded, posterior 2 larger than others. Corolla vexillum ovate-orbicular to oblong, distinctly clawed, veined, crisped at margin; wings oblong, ca. as long as vexillum, clawed; keels narrowly oblong, smaller than wings, clawed. Stamens 10, diadelphous (9+1), sheath 8–9 mm, vexillary filament free to base, filaments of varying heights; anthers versatile. Ovary oblong, 7–8 mm, shortly stipitate, pubescent; ovules 2; style curved; stigma minute. Pod orbicular, 4–4.5 × 3.5–4.5 cm, shortly stalked, flat and indehiscent, prominently winged, 1-seeded. Seed brownish, narrow and oblique, reniform. Fl. Mar–Apr, fr. Apr–May.

China: provinces?? [India, Indonesia (to the Solomon Islands and New Hebrides), Malaysia, Myanmar, Thailand, Vietnam].