1	Leaves pinnate	2
–	Leaves bipinnate	10
2	Armed shrubs or trees, with prickles scattered along the branches, or in pairs below the stipules, or plant with short branches modified into persistent thorns	3
–	Unarmed shrubs or trees	6
3	Sepals persistent in fruit; fruit a cylindrical pod covered with resinous hairs; pairs of needle-like prickles inserted below the stipules and leaf petiole; endemic to northern Chile, from the Coquibo and La Serena valleys	20. Balsamocarpon
–	Sepals caducous; fruit a flattened and non-resinous pod; widely distributed across Central America, Mexico, the Caribbean, South America and Namibia	4
4	Fruit a lomentum, with 4 coarsely serrate wings, breaking up into one-seeded units (articles	2. Lophocarpinia
–	Fruit unsegmented, without wings	5
5	Fruit sub-circular to sickle-shaped, tardily dehiscent along the sutures, finely pubescent and with robust patent trichomes	1. Hererolandia
–	Fruit oblong to fusiform, dehiscent along the middle of the fruit valves or close to the fruit margin, but never along the sutures, lacking patent trichomes	3. Haematoxylum
6	Sepals persistent; fruit a gall-like pod, covered with long bristles	21. Zuccagnia
–	Sepals caducous; fruits ovoid to elliptic pods, not gall-like, glabrous or covered in a different type of indumentum	7
7	Fruit an elastically dehiscent pod, with valves twisting upon dehiscence, laterally-compressed and subligneous to woody, oblanceolate to oblong-elliptic	8
–	Fruit an indehiscent pod, thickened and fleshy, ovoid or elliptic	9
8	Fruit subligneous, lacking a crest; sepals valvate; restricted to Africa and Madagascar; stellate indumentum lacking	17. Stuhlmannia
–	Fruit woody, with conspicuously thickened sutures, sometimes with a crest proximally on the adaxial side; sepals imbricate; restricted to the Neotopics; stellate indumentum often present	18. Cenostigma
9	Fruit elliptic, somewhat thick and fleshy, bright red at maturity, rounded at apex and base, 1–2-seeded; leaflets with black, sessile glands on the under-surface; seeds compressed-turgid; sepals imbricate; endemic to Hispaniola and Puerto Rico	19. Libidibia monosperma
–	Fruit ovoid, apex beaked; 1–4-seeded; leaflets with red glands on the lower surface; seeds ovoid; sepals valvate; endemic to NE Africa	16. Cordeauxia
10	Leaves terminating in a pair of pinnae plus a single terminal pinna	11
–	Leaves terminating in a pair of pinnae	18
11	Plant armed; fruits oblong to fusiform, glabrous, dehiscing along the middle of the valves, or parallel to the margin	3. Haematoxylum
–	Plant unarmed; fruits not dehiscing along the middle of the valves	12
12	Sepals persistent in fruit	23. Hoffmannseggia
–	Sepals caducous in fruit	13
13	Pods cylindrical-torulose; central and western Argentina, in subtropical wooded grassland and scrub, especially on salt pans	22. Stenodrepanum
–	Pods never cylindrical torulose	14
14	Stipules linear, persistent; androecium and gynoecium cupped in the lower cucullate sepal, lower lateral sepals forming a platform at right angles to the abaxial cucullate sepal; pods with simple trichomes, glandular-punctate trichomes, and plumose, dendritic and/or stellate trichomes	25. Pomaria
–	Stipules caducous; androecium and gynoecium not cupped in the lower sepal, deflexed; lateral sepals not forming a platform; fruits glabrous or with simple and/or gland-tipped trichomes, the latter sometimes also dendritic or plumose	15
15	Fruits indehiscent; inflorescence a raceme or panicle, often corymbose; leaflets glabrescent and eglandular, or with glandular dots parallel to the midvein	19. Libidibia
–	Fruits dehiscent, often with twisting valves; inflorescence a raceme or panicle, sometimes pyramidal in shape; leaflets glabrescent to densely pubescent, or with a stellate indumentum; leaflets eglandular, or with dark subepidermal glands, and/or with glandular dots sunken in the margins of the leaflets or parallel to the margin on the abaxial side	16
16	Leaflets alternate, or occasionally nearly opposite (rarely opposite), with dark subepidermal glands (best seen with a x10 hand lens); stellate indumentum sometimes present on foliage and inflorescence rachis; fruit subligneous to woody, with thickened sutures	18. Cenostigma
–	Leaflets always opposite, without dark subepidermal glands; stellate indumentum never present on foliage or rachis; fruit coriaceous to subligneous, sutures not thickened	17
17	Shrubs or small to medium-sized trees varying from (0.5–) 1–12 (–20) meters tall, occasionally functionally herbaceous subshrubs, woody at the base; widespread across low-elevation seasonally dry tropical forests in Mexico, Central America, the Caribbean, and in Caatinga vegetation in Brazil, and in patches of dry forest, deserts, yungas-puna transition zones, and chaco-transition forests in Argentina, Bolivia, Chile and Paraguay; flowers yellow, red, pink or orange, sometimes laterally compressed; ovary eglandular or covered in gland-tipped trichomes, the hairs never dendritic	26. Erythrostemon
–	Small to medium-sized, often decumbent, shrubs, 0.3–2.5 m tall; occurring at mid elevations in dry inter-Andean valleys, in Ecuador, Peru, Bolivia and Argentina; flowers yellow, sometimes all five petals streaked with red markings, never laterally compressed; ovary covered in gland-tipped trichomes, which are sometimes dendritic	24. Arquita
18	Plants unarmed	19
–	Plants armed	22
19	Fruit thin, flat, oblong-elliptic to elliptic, membranaceous to papyraceous, indehiscent; margin of the lower cucullate sepal pectinate-glandular; flowers unisexual; leaflets eglandular	8. Coulteria
–	Fruit an oblong-elliptic pod, elastically dehiscent with twisting valves; margin of the lower cucullate sepal entire; flowers bisexual; leaflets eglandular or with red glands	20
20	Flowers nearly actinomorphic; trees, up to 25 m tall; leaflets eglandular or with red glands; E Africa (Kenya and Tanzania), and N and NW Madagascar	17. Stuhlmannia
–	Flowers clearly zygomorphic; shrubs or small trees, up to 5m tall; leaflets eglandular; Cuba or northern Madagascar (close to Antsiranana)	21
21	Fruits laterally compressed; anthers glabrous; endemic to Cuba (near Moa, in the Sierra de Nipe)	5. Caesalpinia nipensis
–	Fruits inflated and hollow; anthers pubescent; endemic to the northern tip of Madagascar (Orangea peninsula, near Antsiranana)	6. Denisophytum madagascariense
22	Trees or erect shrubs	23
–	Lianas or climbing or trailing shrubs	27
23	Fruits indehiscent, somewhat fleshy, turgid and coriaceous; lower cucullate sepal with a pectinate/fimbriate or entire margin	7. Tara
–	Fruits dehiscent, with valves twisting upon dehiscence, laterally-compressed and subligneous to woody; lower cucullate sepal with an entire margin	24
24	Fruits armed with woody spines, stems with upturned thorns arising from woody protuberances; flowers yellow, the median petal with a conspicuous red blotch on the inner face	4. Paubrasilia
–	Fruits unarmed, stems with straight to deflexed prickles; flowers yellow, white, pink, red or orange	25
25	Flowers pink-purple to whitish pink; bracts broadly ovate to suborbicular with an aristate apex; pyriform pods with rounded, oblique bases; sometimes translucent dots on leaflet lower surface	9. Gelrebia
–	Flowers yellow, red, orange , green or white (horticultural variety sometimes pink); bracts lanceolate to linear with an acute to acuminate apex; pods oblong-elliptic, short-stipitate, with a cuneate base; leaflets eglandular	26
26	Flowers orange, red, green, white, rarely yellow or pink; Central America, Mexico, the Caribbean and the northern Andes (Peru to Colombia)	5. Caesalpinia
–	Flowers yellow, sometimes with red markings on the standard (median petal); Somalia, Ethiopia, Argentina, Paraguay, Mexico, Florida and the Caribbean	6. Denisophytum
27	Fruits with a wing, although this sometimes very narrow	28
–	Fruits without a wing	31
28	Fruit a samara (with a basal 1-seeded chamber and a prolonged upper suture that is broadly winged)	14. Pterolobium
–	Fruit 1 or more seeded, with a longitudinal (often narrow) wing along the upper suture	29
29	Fruit with a wing 2 mm or more wide, chartaceous, coriaceous or ligneous; Africa, Madagascar and SE Asia across the Malay Peninsula and Archipelago to New Guinea, New Caledonia and Australia, one species endemic to Hawaii	15. Mezoneuron
–	Fruit with a wing 2 mm wide or less; coriaceous or ligneous; southern (principally mainland) China, Myanmar (Burma), N Laos and N Vietnam	30
30	Fruit oblong-elliptic, terminating in a sharp beak; 4–9-seeded	13. Biancaea decapetala
–	Fruit rhomboid-circular to sub-elliptic; 1 (rarely 2)–seeded	27. ? Ticanto (Caesalpinia caesia)
31	Glands on stems, leaf rachis, inflorescence, and fruits; needle-like trichomes on inflorescence rachis and pedicels	10. Hultholia
–	Plants eglandular; stems with recurved prickles; pedicels and inflorescence peduncle with a few prickles near their bases	32
32	Fruit oblong to oblong-elliptic	33
–	Fruit broadly elliptic to circular	34
33	Fruit oblong, indehiscent, somewhat fleshy, sub-torulose, with thickened sutures, terminating in an acute apex, exocarp and endocarp strongly adnate; seeds sub-globular	12. Moullava
–	Fruit oblong to oblong-elliptic, laterally compressed, dehiscent, coriaceous to subligneous, with a smooth, regular outer surface, base often much narrower than the truncate apex which terminates in a sharp beak, exocarp and endocarp separate easily; seeds flattened to ellipsoidal	13. Biancaea
34	Flowers unisexual, segregated into female and male racemes; fruits usually covered in spinescent bristles; seeds globose, with parallel fracture lines concentric with the small apical hilum	11. Guilandina
–	Flowers bisexual, in racemes; fruits always glabrous; seeds laterally compressed, smooth, without fracture lines	27. ? Ticanto