| 1 | Upper surface of leaves very finely and closely striate. Inflorescences racemose on leafless stems, usually ferrugineous-tomentose |
| 1' | Upper surface of leaves not striate. |
| 2 | Leaves triplinerved, the main basal pair of nerves extending almost to the leaf-apex. |
| 2' | Leaves not triplinerved. |
| 3 | Woody climber. Drupes ellipsoidal, 40-45 mm long. Sepals and petals streaked with reddish lines or spots |
| 3' | Erect shrub or small tree. Drupes rotund in outline, c. 4 mm long. Sepals and petals not marked with lines or spots 22. |
| 4 | Inflorescences with accrescent rotund bracts becoming up to 1.5 cm long and persisting at fruiting stage, often obscuring the 5 mm long pubescent drupes. Leaves peltate, tomentose to puberulous. Slender climber |
| 4' | Inflorescences without accrescent bracts. |
| 5 | Inflorescences composed of umbelliform cymes or disciform capitula. Drupe with style-scar near base, 4-11 mm long. Endocarp compressed, ± obovate in outline with a sometimes perforate lamelliform condyle surrounded by a horseshoe-shaped seed cavity, dorsally ornamented with projections of various forms or transverse ridges |
| 5' | Inflorescences not of umbelliform cymes or disciform capitula. |
| 6 | Seed and seed cavity straight or broad and concave or deeply cupular. |
| 6' | Seed and seed cavity elongate and strongly curved, semi-annular to horseshoe-shaped. |
| 7 | Seed and seed cavity deeply cup-shaped, surrounding the thickly clavate, sometimes 2-lobed, deeply intrusive condyle. Drupes subglobose. Leaves palmately nerved at base. |
| 7' | Seed and seed cavity either straight, ± ellipsoidal and endocarp with condyle absent, inconspicuous or forming a longitudinal groove, or seed dorsiventrally flattened and concave and endocarp with condyle forming a ventral cavity, concavity or inflated chamber. |
| 8 | Lower surface of leaves with domatia in axils of main nerves. Drupes 9-11 mm ø |
| 8' | Leaves without domatia. Drupes over 25 mm ø. |
| 9 | Drupes 40-45 mm ø, glabrous. Endocarp covered with branched spines. Leaves glabrous |
| 9' | Drupes 28-30 mm ø, tomentellous. Endocarp not spiny. Leaves tomentellous (usually whitish) on lower surface |
| 10 | Seed ± ellipsoidal filled by large embryo with thick cotyledons, endosperm absent. Leaves penninerved, sometimes with some subbasal nerves. |
| 10' | Seed largely filled with endosperm which surrounds the very thin embryo. Leaves palmately nerved at base or with basal nerves diverging from midrib slightly above the base. |
| 11 | Drupes narrowed at base into a pronounced stipe, 5-10 radiating from margin of a disciform carpophore. Endocarp 3-6 cm long, bony, covered dorsally with a coarse open network of ridges, ventrally smooth. Inflorescences fasciculate on protuberances on old wood. Leaves densely reticulate |
| 11' | Drupes with base not narrowed into a stipe, 3-6 on a knob-like carpophore. Endocarp either papyraceous to crustaceous and ± smooth to wrinkled or bony and verrucose. |
| 12 | Drupes subcompressed-ellipsoidal, tomentellous with style-scar near base, 2.5-6 cm long. Inner sepals connate into a fleshy tube |
| 12' | Drupes subglobose or broadly ellipsoidal, glabrous puberulous or tomentellous with style-scar below the apparent apex, 0.8-3 cm long. Sepals all free |
| 13 | Lower surface of leaves with hollow domatia in axils of main nerves, leaf papillose on upper surface around insertion of petiole. Drupes 2.2-5.5 cm long with style-scar on one side, borne on a clavate carpophore up to 4 cm long. Endocarp covered with a fibrous layer, condyle inconspicuous or absent |
| 13' | Lower surface of leaves without domatia or only present in basal nerve-axils. Drupes with terminal style-scar. |
| 14 | Basal nerves of the leaf diverging from the midrib several mm above the base. Endocarp rather smooth, subellipsoidal, 2.0-2.5 cm long, the condyle forming a ventral narrow longitudinal groove. Inflorescence a lax panicle. Wood yellow |
| 14' | Basal nerves arising from the base of the leaf. Endocarp variously ornamented or smooth, often ± rotund in outline but sometimes subellipsoidal. Wood not yellow. |
| 15 | Endocarp spiny, the condyle forming a ventral concavity or an enclosed inflated chamber. Endosperm not ruminate |
| 15' | Endocarp rugose, papillose or smooth with the condyle forming either a ventral cavity with a central external aperture, or a ventral elongate depression. Endosperm usually ventrally ruminate |
| 16 | Drupes 6-7 mm long borne on a shortly branched 3-4 mm long carpophore. Carpels 8-9. Petioles rugulose |
| 16' | Drupes not on a conspicuous carpophore. Carpels 1-6. Petioles not rugulose. |
| 17 | Leaves penninerved. Drupes and narrowly thyrsoid inflorescences tomentellous. |
| 17' | Leaves with base palmately 3-7-nerved. Drupes glabrous to pubescent. |
| 18 | Petals fleshy, larger than the sepals. Drupes semicircular in outline, (4-)6 mm long. Endocarp ornamented dorsally with pointed processes and/or transverse ridges, laterally concave. Seed and seed cavity semi-annular. Leaves subpeltate or peltate with petiole inserted up to 3 mm from basal margin, fine reticulation prominent especially on lower surface. Woody stems verruculose |
| 18' | Petals, if present, much smaller than the sepals. Seed and seed cavity mostly ± horseshoe-shaped. |
| 19 | Inflorescences from old woody stems, consisting of very long racemes of cymes, up to c. 50 cm long. Drupes narrowly obovate in outline, 15-30 mm long. Seed and seed cavity deeply horseshoe-shaped with the 2 arms ± parallel |
| 19' | Inflorescences axillary. Drupes obovate to rotund in outline. |
| 20 | Endocarp with an entire dorsal median wing or ridge and laterally spreading curved or cucullate crests bordering the condyle, the dorsal region smooth (Mal. spp.). Petals absent |
| 20' | Endocarp without a dorsal median wing or prominent ridge and lateral crests, the dorsal region sometimes ornamented, e.g. verruculose, ridged or spinulate. Petals present. |
| 21 | Seed without endosperm, cotyledons large and thick, collateral. Endocarp rather smooth with a small central perforation on both lateral faces |
| 21' | Seed with endosperm surrounding the narrow embryo. |
| 22 | Drupes 14-25 mm long. Dorsal region of endocarp smooth or only slightly rugose. Condyle hollow, 2-chambered. Inner sepals valvate |
| 22' | Drupes less than 12 mm long. Dorsal region of endocarp often ornamented. Condyle lamelliform or hollow. Inner sepals imbricate. |
| 23 | Leaves with main basal nerves and their main outer lateral branches leading directly to the margin, which is usually broadly and shallowly crenate. Endocarp laterally concave, dorsally covered with short pointed processes, condyle lamelliform, imperforate |
| 23' | Leaves with main nerves breaking up well within the entire margin. Endocarp with thick, hollow condyle, often perforate. |
| 24 | Condyle 1-chambered with or without a small lateral perforation on each side. Endocarp with a ventral perforation, dorsal surface with ± papilliform processes and/or transverse ridges in longitudinal rows. Drupes 5-8 mm long. Carpel 1. Sepals 2 or 3. Petals entire. Leaves sometimes peltate |
| 24' | Condyle with 2 distinct lateral chambers each with a large lateral aperture. Endocarp not ventrally perforate. Carpels (2-)3 or 6. Sepals 6-12. Leaves never peltate. |
| 25 | Drupes 6-12 mm long. Dorsal surface of endocarp rugose. Carpels (2-)3. Sepals spiral, 7-12. Petals entire |
| 25' | Drupes 4-5 mm long. Dorsal surface of endocarp closely and irregularly wrinkled-papillose. Carpels 6. Sepals 6(-9) in 2(-3) whorls. Petals bifid 22. |
