Isolona hexaloba Engl.

Tree up to 25-30 m high; d.b.h. to 50 cm, fluted; bark smooth, brown or grey greenish; young branches drying black, glabrous, old branches light grey, glabrous. Petioles 2-4 mm long, 2-3 mm in diameter, glabrous, leaf lamina inserted on side, grooved adaxially. Leaf lamina 10-28 cm long, 3-11 cm long, length:width ratio 2.3-4, narrowly ovate to ovate or narrowly elliptic to elliptic, coriaceous, shiny dark green above, light green below, glabrous, base acute or rarely obtuse, apex acuminate, acumen 1-2 cm long; midrib proximally depressed adaxially, glabrous on both sides; secondary veins 8-16 pairs, uniformally curving upwards, loop forming towards margins, glabrous. Rhipidia 1-2, on leafy branches. Flowering pedicels (7-)13-25(-30) mm long, ca. 0.5 mm in diameter, glabrous, green. Lower bracts 2-4, ca, 0.5 mm long, ca. 0.4 mm wide, glabrous, margins covered with short appressed hairs. Upper bract at the base of the pedicel, 2-5 mm long, 1 mm wide, glabrous, margins covered with short erect hairs. Sepals 1-3 mm long, 2-4 mm wide, length:width ratio 0.5-1, transversely elliptic to elliptic, base truncate, apex shortly acuminate, glabrous, green, pressed against tube, falling in fruit; margins with short erect hairs. Corolla white to yellow or green when immature to dark red at anthesis; tube 4-10 mm long, 4-7 mm in diameter, lobe:tube ratio 1-5, glabrous; lobes 6-25 mm long, 4-12 mm wide, length:width ratio 1.3-2, elliptic or ovate, narrowed at base, apex acute to rounded, glabrous, coriaceous, spreading horizontally. Receptacle 4-6 mm in diameter. Stamens 1.8-2 mm long; connective shield ca. 0.1 mm long, glabrous, those of innermost row elongated over ovary wall. Ovary ca. 1 mm long, ca. 0.5 mm wide; stigma ca. 2 mm in diameter, glabrous, light red at anthesis. Fruiting pedicels 20-25(-29) mm long, 3-5 mm in diameter, woody. Fruits 3-7 cm long, 2.5-4 cm in diameter, broadly ovoid, lumpy, irregularly and transversely ribbed, glabrous, light green to dark purple-red when mature; pericarp 3-4 mm thick. Seeds 8-15 mm long, 4-6 mm in diameter, transversely ellipsoid; testa rugose, light brown; raphe thickened, darker brown; hilum 3-5 mm long, 2-3 mm wide, elliptical.