1Stomatal crypts absent from leaf underside; leaf underside glabrous or with a persistent lanate pubescence and then with large persistent stipules 7-40 mm.
1'Stomatal crypts present on leaf underside; leaf undersurface lanate or at least pubescent in crypts; stipules usually small, or if larger then early caducous.
2Leaf undersurface glabrous. Stipules small and caducous.
2'Leaf undersurface densely lanate pubescent, but when removed no stomatal crypts present; stipules large and persistent, 7-40 mm long, 3-5 cm broad at base.
3Leaves elliptic to oblong or obovate-elliptic, 9.5-20.5 by 4.5-8.5 cm; primary veins 11-16 pairs. Panicles large and silvery pubescent
3'Leaves ovate, 5-9 by 2-4.5 cm; primary veins 7-11 pairs. Panicles small and subsericeous brown pubescent
4Leaves oblong-lanceolate, 5-18 cm long on flowering branches, thickly coriaceous, base cuneate
4'Leaves elliptic to oblong, 11-28 cm long, chartaceous, base rounded
5Leaf lower surface with a series of small glands along lower part of margin. Calyx broadly cupuliform.
5'Leaf lower surface without marginal glands on lower part. Calyx usually campanulate.
6Leaf apex acute or rounded but not acuminate; primary veins 10-17 pairs. Young branches with small, almost plane lenticels. Low tree of savanna, savanna forest and forest margins
6'Leaf apex acuminate, acumen 3-10 mm long; primary veins 16-22 pairs; young branches with extremely prominent large lenticels; large tree of rain-forest and hills
7Primary leaf veins 20-33 pairs (16-26 pairs in P. costata subsp. polyneura).
7'Primary leaf veins 20 pairs or fewer.
8Petioles 9-17 mm long
8'Petioles 3-6 mm long.
9Leaves chartaceous, primary veins prominulous above, 16-26 pairs
9'Leaves coriaceous, primary veins impressed for upper portion, 20-28 pairs
10Petioles 10-20 mm long; leaves with or without a metallic sheen above.
10'Petioles 3-10 mm long; leaves without metallic sheen.
11Leaves with metallic sheen above; petioles 14-20 mm long; leaves 4-9 cm broad. Borneo
11'Leaves without metallic sheen; petioles 10-12 mm long; leaves 6.5-12 cm broad. New Guinea
12Leaves rigidly coriaceous, often broadest well below mid point; midrib and often primary veins lightly impressed on upper surface
12'Leaves thinly coriaceous or chartaceous, usually broadest at or above middle (except in P. insularum); midrib and primary veins usually plane or prominulous.
13Leaves ovate, with long thin acumen, tapering from well below mid point; midrib impressed above. Plants of Pacific Islands (Fiji, Tonga, Samoa, Wallis Is.)
13'Leaves elliptic to oblong-lanceolate, tapering from middle or above; midrib usually plane or prominulous. Plants of Sunda shelf.
14Inflorescence predominantly axillary. Leaves broadly elliptic
14'Inflorescence terminal and subterminal. Leaves elliptic to narrowly oblong.
15Leaf apex rounded to acute. Thailand and Indochina
15'Leaf apex acuminate. Burma, Malay Peninsula, Indonesia and the Philippines