Isolona pleurocarpa Diels

Tree up to 15-30 m high; d.b.h. to 40(-60) cm, fluted; bark thick, black with grey markings;; young branches drying black, glabrous; old branches dark grey, rugulose longitudinally, glabrous. Petioles 4-8(-12) mm long, ca. 1 mm in diameter, glabrous, leaf lamina inserted on side, broadly grooved adaxially. Leaf lamina 8.5-15.5 cm long, 3-6 cm wide, length:width ratio 2.5-3.5, narrowly elliptic to elliptic or narrowly obovate to obovate, subcoriaceous to papyraceous, glabrous, light green abaxially, dull dark green adaxially, base decurrent to narrowly cuneate, apex acuminate, acumen 1-1.5 cm long; midrib proximally depressed above, glabrous on both sides; secondary veins 9-12 pairs, uniformally curving upwards, glabrous on both sides. Rhipidium 1, on leafy branches. Flowering pedicels 10-20(-23) mm long, ca. 1 mm in diameter, glabrous. Lower bracts 2-6, ca. 1 mm long, ca. 1 mm wide, glabrous; margins with short appressed hairs. Upper bract inserted in the basal half of the pedicel, ca. 1 mm long, ca. 1 mm wide, glabrous; margins with short appressed hairs. Sepals 2-3 mm long, 2-3 mm wide, length:width ratio 0.6-1, depressed ovate to broadly ovate, base truncate, apex acuminate, glabrous, green, appressed against tube, falling in fruit; margins with short appressed hairs. Corolla bright green-white when immature, yellow with red tube at anthesis; tube (6-)9-15 mm long, lobe:tube ratio 1.6-3, verruculose when dried, glabrous; lobes 10-23 mm long, 5-10 mm wide, length:width ratio 1.6-3.5, narrowly ovate to ovate, narrowed at base, apex acute, glabrous, papyraceous, the margins undulate-wavy when dried. Receptacle ca. 4 mm in diameter. Stamens 1.7-1.9 mm long; connective shield ca. 0.2 mm long, glabrous, those of innermost row stretched and pressing against ovary wall. Ovary ca. 2.2 mm long, ca. 2 mm wide; stigma ca. 2.5 mm in diameter, sparsely covered with short erect hairs. Fruiting pedicels ca. 3 cm long, 3-4 mm in diameter, woody, rugulose in longitudinal lines, glabrous. Fruits ca. 5 cm long, ca. 4 cm in diameter, length:width ratio ca. 1.25, globose, apicule absent, conspicuously longitudinally 6-8 ribbed, rugulose all over, glabrous, green when immature. Seeds not seen.