紫矿 zi kuang

Erythrina monosperma Lamarck, Encycl. 2: 391. 1786; Butea frondosa Roxburgh ex Willdenow, nom. illeg. superfl.

Trees, 10-20 m tall. Trunk to 30 cm d.b.h. Bark grayish black. Petiole ca. 10 cm, robust; stipels subulate, ca. 1.5 mm; petiolules robust, ca. 8 mm; leaflets unequal, thickly leathery, rough on both surfaces, puberulent along veins abaxially, gla­brous adaxially, lateral veins 6 or 7 pairs, like midrib raised abaxially, reticulate veins distinct and with conspicuous areoles abaxially; terminal leaflet broadly obovate or suborbicular, 14-17 × 12-15 cm, base broadly cuneate, apex rounded or emar­ginate; lateral leaflets narrowly ovate or oblong, 11.5-16 × 8.5-10 cm, asymmetric, base rounded, apex obtuse or emarginate. Racemes or panicles axillary or at nodes of leafless branches; rachis, pedicels, and calyx outside densely brown or blackish brown velutinous. Calyx 1-1.2 cm, densely silvery gray on both surfaces or light brown pubescent inside. Corolla orange-red, becoming yellow later, ca. 3 × as long as calyx; standard nar­rowly ovate, recurved, 4-4.5 cm; wings narrowly falcate, ca. 4 cm, like keel with rounded auricles at base; keel broadly falcate, 5-5.5 cm, connate into an arcuate ridge, densely silvery gray velutinous. Anthers oblong. Ovary densely velutinous. Leg­umes 12-15 × 3.5-4 cm, adpressed silvery gray puberulent, apex rounded; stipe 12-15 mm. Seed reddish brown, broadly reniform or reniform-orbicular, compressed, ca. 2.7 × 3.3-3.6 cm. Fl. Mar-Apr.

Forests, wet places, near roads, also cultivated. SW Guangxi (Ningming), S and SW Yunnan (Gengma, Xishuangbanna) [Bhutan, Cambodia, India, Indonesia, Laos, Myanmar, Nepal, Sri Lanka, Thai­land, Vietnam].

This species is one of the main host plants of lac insects. The red resin from the bark is used medicinally as an astringent.