| 1 | Branchlets angular or winged. |
| 1' | Branchlets terete |
| 2 | Leaflets chartaceous, subsessile, with diagonal main vein; lateral veins just visible beneath; lower surface puberulous or velutinous, papillose. |
| 2' | Leaflets coriaceous, petiolulate, petiolule 2-5 mm long; main vein central or sub-central, lateral veins prominent and raised beneath, not papillose. |
| 3 | Leaflets with 7-14(-20) lateral veins per side, parallel, oblique, straight; lower surface subglabrous, with a few scattered hairs on the major veins. Pod forming a circle or a rounded square, c. 3.5 cm in diameter, prior to dehiscence |
| 3' | Leaflets with 6-10 lateral veins per side, not parallel, arching; lower surface puberulous. Pod spirally contorted, 14-25 by 1.5-2.2 cm |
| 4 | Pods straight or slightly curved, usually sausage-shaped. |
| 4' | Pods curved into a half or full circle, or spirally contorted, not sausage-shaped. |
| 5 | Valves reddish or orange inside. Petiolar glands not urceolate |
| 5' | Valves grey or brownish inside. Petiolar gland (sub)urceolate |
| 6 | Fruits borne on the old wood; pods large and sausage-shaped, c. 15-50 by 4-8.5 cm |
| 6' | Fruits terminal on twigs; pods smaller, up to 3 cm wide |
| 7 | Basic unit of infructescence a raceme (i.e., scars of pedicels evenly distributed along the inflorescence axis) |
| 7' | Basic unit of infructescence an umbel (i.e., scars of pedicels aggregated at the end of the peduncle) |
| 8 | Pod usually slightly flattened, densely puberulous when young, subglabrous and yellowish outside at maturity, 3.5-10 by 1.5-2.5 cm. Central seeds disc-like |
| 8' | Pod only slightly flattened, glabrous, bright red to reddish brown at maturity, 4.5- 18 by 1.5-2.5 cm. Central seeds ellipsoid, but occasionally truncate in the parts adjacent to other seeds |
| 9 | Pods bright red outside at maturity, 4.9-9 by 1.7-2.5 cm. |
| 9' | Pods reddish brown outside at maturity, 13-18 by 1.8-2 cm. |
| 10 | Seeds imbedded in a ± fleshy coriaceous pericarp giving the pod a segmented appearance internally, dehiscent along the sinuate dorsal suture (2. Series Archidendron) |
| 10' | Seeds not imbedded in a fleshy pericarp; pod sinuate along the ventral suture, dehiscing either first along the ventral suture or along both sutures simultaneously (1. Series Clypeariae, for the greater part) |
| 11 | Petiolar glands narrowly conical, often hollow, 1-5 mm high |
| 11' | Petiolar glands circular or elliptic in outline, not raised |
| 12 | Pods muricate by blunt, protruding tubercles |
| 12' | Pod smooth outside |
| 13 | Pods tomentose outside |
| 13' | Pods glabrous outside |
| 14 | Pod slightly curved or curved into a circle, c. 10 by 2-3 cm |
| 14' | Pod densely contorted, c. 24 by 3 cm wide across the seeds. |
| 15 | Petiolar gland deeply hollowed, with the orifice pointing forwards |
| 15' | Petiolar gland circular, urceolate, elliptic, oblong or slit-like, when with orifice then not directed forwards |
| 16 | Pods rugulose or wrinkled outside |
| 16' | Pods smooth outside |
| 17 | Pod glabrous |
| 17' | Pod tomentose outside |
| 18 | Valves of pods woody, sinuate for about halfway or more along the dorsal suture, distinctly contracted between the seeds |
| 18' | Valves of pods chartaceous or coriaceous, rarely woody, not or only slightly sinuate |
| 19 | Petiolar gland circular, convex (subglobose) or flat |
| 19' | Petiolar gland slit-like, sunken. |
| 20 | Petiole hollow; leaflets drying greenish with yellowish brown veins, very broadly ovate-elliptic with rounded base |
| 20' | Petiole solid; leaflets drying dark green to blackish above and light green to lead- grey beneath, ovate-elliptic to broadly elliptic or lanceolate, with symmetrically cuneate base |
| 21 | Pods hairy |
| 21' | Pods glabrous |
| 22 | Foliar glands urceolate with a narrow orifice |
| 22' | Foliar glands circular or elliptic |
| 23 | Leaflets 10-22 pairs per pinna |
| 23' | Leaflets 2-4 pairs per pinna |
| 24 | Two kinds of pods in the infructescence: the marginal ones smaller and sterile, the central ones larger and fertile, c. 2-3 cm long, 0.5-1.5 cm wide |
| 24' | Only one kind of pods in the infructescence |
| 25 | Leaflets with 8-14(-20) parallel, raised, straight, oblique lateral veins |
| 25' | Leaflets with arching and usually non-parallel, primary lateral veins |
| 26 | Infructescence borne below the leaves on old wood |
| 26' | Infructescence terminal on branchlets |
| 27 | Leaflets chartaceous, drying bright green with straw veins. Pods loosely twisted into a spiral, c. 15-20 by 1.8-2.4 cm. Seeds 16 by 12 by 10 mm |
| 27' | Leaflets coriaceous to chartaceous, drying grey-green to dark brown. Pods densely contorted into a circle, c. 3.5-4.5 cm in diameter. Seeds c. 6-9 by 5-7 by 3-4 mm |
| 28 | Foliar glands urceolate or concave, circular or sometimes linear-oblong. Stalk of pod articulate. Seeds ellipsoid |
| 28' | Foliar glands slit-like. Stalk of pod not articulate (flowers sessile). Seeds suborbicular |
| 29 | Primary lateral veins (l-)2-3(-4) per leaflet-half; lateral veins issuing in the proximal part of the leaflet, arching to the apex |
| 29' | Primary lateral veins (4 or) 5 or more per leaflet, issuing ± equally along the main vein, not arching to the apex |
| 30 | Pods large, usually with valves more than 2 cm wide across the seeds. Seeds more than 17 mm long. |
| 30' | Pods smaller, usually with valves less than 2 cm wide across the seeds. Seeds ellipsoid, 17-21 by 10-11 mm |
| 31 | Leaflets with minute, reddish, sessile glandular hairs on the lower surface, especially close to the main vein (lens!); petiolar gland circular or semiglobose. |
| 31' | Leaflets without glandular hairs; glands flat and either circular, oblong, rhomboid, or obtriangular, often obtriangular on the pinnae. |
| 32 | Leaflets densely appressed puberulous with hirsute veins beneath |
| 32' | Leaflets scarcely puberulous or glabrous beneath |
| 33 | Foliar glands circular or transversely elliptic. Pod woody, large, falcate, 7-13 by 2-3.3 cm. Seeds subglobose or very broadly ellipsoid, 20-22 by 18-20 by 14- 20 mm |
| 33' | Foliar glands either oblong, rhomboid, or obtriangular. Pod coriaceous, curved into a circle, 4.5-8 cm in diameter, 2-3.5 cm wide across the seeds. Seeds ellipsoid, 17-21 by 10-11 mm |
| 34 | Leaves with (1 or) 2 or 3 pairs of pinnae. Pods coriaceous, usually found below the leaves |
| 34' | Leaves with 1 (or 2) pair(s) of pinnae only. Pods chartaceous to coriaceous, found above the leaves |
| 35 | Rachis-glands oblong-elliptic, 2.5-6 mm. Seeds 12-15 mm long |
| 35' | Rachis-gland 1, broadly elliptic or circular, 1-3 mm. Seeds 8-9 mm long |
