Kopsia arborea Blume, Catalogus 13. (1823)

Species name meaning 'tree-like'.

Kopsia jasminiflora Pitard
Kopsia lancibracteolata Merr
Kopsia laxinervia Merr
Kopsia longiflora Merr
Kopsia officinalis Tsiang & P.T.Li
Kopsia pitardii Merr
Kopsia pruniformis Reichb.f. & Zoll. ex Bakh.f.
Kopsia scortechinii King & Gamble

It is a relatively short tree with oppositely arranged elliptic leaves with wavy margins. A useful guide is to look out for the old leaves which will turn reddish or purple (almost always present). The flowers are white with a faint yellow centre while the fruits is ovoid in shape and dark purple-blue when ripe, without any projections.

Tree to 14 m tall, to 30 cm dbh. Bark gray; inner bark pale brown. Branchlets glabrous or sparsely puberulent when young, sparsely lenticellate or not. Leaves: petiole 3-10 mm long, glabrous; blade 4.5-30.5 x 1.4-12.0 cm, 1.9-5.7 times as long as wide, subcoriaceous to coriaceous, elliptic, apex caudate to acuminate with a blunt tip, base acute or cuneate, glabrous above and beneath, midrib sunken to raised and with a central groove above, secondary veins 9-18 pairs with 4-13 mm spacing, 60-65 degrees from midrib, prominent above and beneath, clearly distinguishable from tertiary venation above and beneath, straight or ascending near margin, tertiary venation prominent or flat above and beneath, obscure or irregularly subperpendicular to midrib and oblique to secondary veins, intramarginal vein strongly looped. Inflorescence dichasial, 4.8-15.3 cm long with axes 2.0-12.5 cm long and branches 1.2-2.7 mm wide, glabrous to sparsely puberulent; peduncle 0.7-8.1 cm long, 2.1-2.7 mm wide, glabrous or puberulent in upper parts; pedicels 0-5 mm long, glabrous to densely puberulent, subtending bracts persistent, bracts present on pedicel. Sepals 1.8-6.3 x 0.6-1.9 mm, 1.0-3.7 times as long as wide, ovate, lanceolate or oblong, apex obtuse to acute, ciliate, glabrous to sparsely puberulent outside, glabrous or puberulent on upper half inside. Corolla completely white; tube 20.5-35.0 mm long, 1.6-2.2 mm wide, 1.3-2.7 times as long as lobes, 5.4-13.6 times as long as calyx, glabrous to sparsely pubescent around stamens and slightly beneath inside, glabrous or sparsely puberulent at top of tube outside; lobes 7.0-21.5 x 3.4-6.5 mm wide, 1.6-4.4 times as long as wide, elliptic or oblong, apex rounded to obtuse, ciliate or ciliate only at lobe base, inside glabrous or sparsely pubescent in upper quarter, outside glabrous. Stamens inserted 18.0-32.3 mm from corolla base which is 0.8-0.9 of corolla tube length in the rehydrated flowers measured; anthers 1.2-1.7 x 0.5-0.8 mm, 2.0-3.4 times as long as wide, apex 0.1-1.4 mm from corolla throat; filaments 0.8-1.2 mm long. Disk 0.7-2.1 mm long, 1.1-1.9 times as long as ovaries, glabrous, oblong, hourglass-shaped, or awl-shaped, apex shape variable and often quite complex, ranging from simply acuminate to rounded to horizontally V-shaped and flat on top or horizontally V-shaped and retuse on top. Ovaries 0.9-1.2 mm high, glabrous to sparsely pubescent all over; style 18-25 mm long; style head 0.8-1.1 mm long. Fruit oblique ellipsoid or subglobose, blue-black, 14.0-42.4 x 5.5-15.5 x 8-22 mm, only one carpel developing (see note), spur absent, glabrous. [from Harvard Papers in Botany, Vol. 9, No. 1, 2004, pp. 89-142]

Grows in a wide range of forest types as an understory tree and at forest margins on a wide range of soil types from sea level to 1500 m altitude.

A decoction of bark is used as an enema. The leaves and fruit are used to treat sore throat and tonsillitis.

Andaman and Nicobar Islands, southern China, Thailand, Vietnam, peninsular Malaysia, Borneo, Sumatra, Java, Lesser Sunda Islands, Sulawesi, Philippines, Queensland.

Local names
China: Rui mu.
English: Penang Sloe.