| 1 | Herbaceous with woody base: |
| 1' | Leaves simple, usually more or less bilobed, sometimes deeply divided (seemingly bifoliolate). Venation palmate (or fan-like), or parallel: |
| 1'' | Young leaves in pendent, linear, stipular or bracteate sheath buds (up to 20 cm long): |
| 1''' | Leaves bifoliolate. Leaflets and floral parts pellucid-punctate. Pods indehiscent: |
| 1'''' | Leaf-stalks or axes of inflorescences sometimes bearing nectariferous glands |
| 1''''' | Leaflets sometimes with a pair of wart-like glands at the base and/or at the apex: |
| 1'''''' | Leaflets usually with 1 or 2 small crateriform glands at the basal part on lower surface: |
| 1''''''' | Leaflets opposite, asymmetric, the midrib usually excentric and close to the upper margin. Buds covered by 2-ranked, caducous bud-scales. Inflorescences axillary, sessile, globular, contracted: |
| 1'''''''' | Rachis of pinna elongate, flattened, phyllodial, ending in a spine, persistent. Leaflets tiny, numerous. Pods often constricted between the seeds: |
| 1''''''''' | Spines often branched: |
| 1'''''''''' | Leaves bipinnate, armed: |
| 1''''''''''' | Leaves bipinnate, unarmed: |
| 1'''''''''''' | Inflorescences long, hanging racemose, loosely flowered. Flowers large, showy, red. Petals 5.7-7 cm long: |
| 1''''''''''''' | Inflorescences short, compact, mostly nodding capitate, densely flowered: |
| 1'''''''''''''' | Calyx lobes often with spiny outgrowths on the outer surface: |
| 1''''''''''''''' | Calyx and corolla pellucid-glandular: |
| 1'''''''''''''''' | Petals absent, or 1-5 petals greatly reduced: |
| 1''''''''''''''''' | Petals: only 1 developed, the others rudimentary or wanting: |
| 1'''''''''''''''''' | Stamens many, 15-80; filaments often connate at the base: |
| 1''''''''''''''''''' | Stamens: often only 2 fertile: |
| 1'''''''''''''''''''' | Stamens with filaments more or less equal in length; filaments pilose at the basal part: |
| 1''''''''''''''''''''' | Anther-thecae dehiscing by apical or basal pores, or short slits: |
| 1'''''''''''''''''''''' | Anthers ± hairy at apical and/or basical ends: , |
| 1''''''''''''''''''''''' | Pods often spiny: , |
| 1'''''''''''''''''''''''' | Pods rather big, globose or subglobose, drupaceous, c. 6 cm in diam., with a roughish, somewhat scrufy-granular brown surface: |
| 1''''''''''''''''''''''''' | Pods winged along both sutures: |
| 1'''''''''''''''''''''''''' | Pods surrounded by a broad, papery wing: |
| 1''''''''''''''''''''''''''' | Pods winged along only one suture: |
| 1'''''''''''''''''''''''''''' | Pods samaroid, with an oblique or falcate wing above the seed bearing part: |
| 1''''''''''''''''''''''''''''' | Pods dehiscing at the apex only: |
| 1'''''''''''''''''''''''''''''' | Pods indehiscent, drupe-like: |
| 1''''''''''''''''''''''''''''''' | Seeds with strongly folded cotyledons (easily seen in section). Slashed wood usually exuding a green sap (see field note): |
