1Leaves simple, usually more or less bilobed, sometimes deeply divided (seemingly bifoliolate). Venation palmate (or fan-like), or parallel
1'Leaves compound, rarely unifoliolate (or seemingly a simple leaf). Venation neither palmate (or fan-like) nor parallel
2Leaves bipinnate
2'Leaves simple pinnate, rarely unifoliate
3Plants armed with prickles, spines or thorns
3'Plants not armed
4Spines often branched, especially those on the trunks and branches. Flowers actinomorphic. Petals 3-5. Stamens 6-10 fertile
4'Spines simple. Flowers slightly zygomorphic or bilateral. Stamens 10, all fertile
5Leaf-rachis very short, spine-like. Rachides of pinnae flattened, phyllodial. Leaflets tiny, numerous, caducous. Pods constricted externally between the seeds..
5'Leaf-rachis not spine-like. Rachides of pinnae neither flattened nor phyllodial. Leaflets several to many, small to large, not caducous. Pods not like above
6Floral parts often punctate. Calyx lobes and petals usually (markedly) zygomorphic. Ovary 1-10(-13)-ovuled
6'Floral parts not punctate. Calyx lobes and petals slightly unequal. Ovary 1-3-ovuled.
7Leaves often with only 1 pair of pinnae. Pods wingless, dehiscent
7'Leaves with 4-17 pairs of pinnae. Pods obliquely winged above, indehiscent
8Petals 3-7 cm long, with long claw
8'Petals 0.25-2.5 cm long
9Stamens 5
9'Stamens 10
10Leaflets (1 or) 2 (3-6) pairs per pinna. Petals small, 2.5-5 mm long. Stamens with glabrous filaments. Pods dehiscent in two valves..
10'Leaflets often more pairs (4-27) per pinna. Petals much larger, 12-25 mm long. Stamens with filaments pilose or villous at the base or basal part. Pods indehiscent or dehiscing at the apex only
11Leaves imparipinnate
11'Leaves paripinnate
12Petals 5. Pods winged
12'Petals absent, or greatly reduced (Dialium). Pods not winged
13Stamens 5. Ovary 1-ovuled. Pods surrounded by a broad, papery wing
13'Stamens 7-9 (4 or 5 fertile, 2-4 staminodes). Ovary 3-5-ovuled. Pods with a narrow wing along one suture
14Calyx lobes or sepals 4. Pods dehiscent, l-4(-6)-seeded
14'Calyx lobes or sepals usuallly 5. Pods indehiscent, 1-seeded
15Inflorescences racemose. Ovary 1-6-ovuled. Pods l-4(-6)-seeded. Seeds exarillate
15'Inflorescences paniculate. Ovary 2-ovuled. Pods 1- or 2-seeded. Seeds arillate.
16Fertile stamens 10. Ovary 1-ovuled. Pods often flattened. Cotyledons strongly folded (seen in section)
16'Fertile stamens usually 2. Ovary 2-ovuled. Pods often globose. Cotyledons not folded
17Pods with a thin crustaceous, usually hairy exocarp, easily crushed or sometimes detached from mesocarp
17'Pods with a crustaceous, glabrous exocarp, united with a thick (c. 4-5 mm) and hard mesocarp, uncrushable by hard press between two hands
18Inflorescences short, compact, nodding capitate, peduncle and rachis together less than5cm long, densely flowered. Young leaves in pendent, linear, stipular or bracteate sheath buds (up to 20 cm long)
18'Inflorescences and young leaves not like above
19Bracteoles large, red, (4.5-)8-9 cm long, persistent
19'Bracteoles small or minute, not red, less than 2.5 cm long, often caducous.
20Petals absent
20'Petals present, 1-5
21Only 1 petal developed, the others rudimentary or wanting
21'Often 2-5 petals developed
22Calyx lobes often spiny outside. Fertile stamens often 10. Pods often spiny outside
22'Calyx lobes smooth outside. Fertile stamens 3-8
23Stamens often (5-)7 fertile. Seeds arillate
23'Stamens often 3 fertile. Seeds not arillate
24Calyx lobes or sepals often 4. Pods indehiscent
24'Calyx lobes or sepals usually 5. Pods dehiscent
25Petals often 2 or 3 developed, with or without reduced ones. Fertile stamens 3; filaments and staminodes connate about half their length into a pubescent tube.
25'Fertile stamens 2 or 10, free or filaments and staminodes connate at the base into a glabrous, very short incomplete ring
26Fertile stamens 10, free
26'Fertile stamens 2, free, or filaments and staminodes connate at the base
27Stipules foliaceous, persistent. Stamens and staminodes free
27'Stipules very small, caducous. Stamens and staminodes connate at the base..
28Stamens 15-80; filaments often connate at the base
28'Stamens (5-)10(-15); filaments free
29Anther-thecae dehiscing lengthwise
29'Anther-thecae dehiscing by apical or basal pores or short slits
30Calyx and corolla pellucid-glandular. Pods rather big, up to 36(-67) cm long, dehiscent
30'Calyx and corolla not as above. Pods rather small, less than 6 cm long, indehiscent
31Stamens 10, 3 abaxial ones with long filaments sigmoidally curved, the anthers dehiscing by short slits; remaining 7 with short and straight filaments, the anthers dehiscing by basal pores
31'Stamens 10, 5-7 or all fertile; filaments straight, the anthers dehiscing by short slits or apical pores
32Anther-thecae ciliolate along the sutures. Pods elastically dehiscent; valves coiling
32'Anther-thecae glabrous. Pods either indehiscent or dehiscent through 1 or both sutures; valves not coiling