Key to the Native and Naturalized Genera of Ingeae
(Leguminosae: Mimosoideae) in the Neotropics
by R. C. Barneby & J. W. Grimes
by R. C. Barneby & J. W. Grimes
[N. B.: This pragmatic key to native, naturalized and planted genera of Ingeae in the Americas is designed exclusively for purposes of identification. 1. Stems armed at all or at most nodes with either a) a pair of spinescent stipules, or b) a pair of spines at each node, one arising from dorsal face of each stipule, or c) one or two axillary thorns [if misled hither by plant armed at nodes with a pair of epidermal prickles, see Acacia] 2. Stipules not modified into spines, the stem-nodes armed with: 3. A spine emergent from dorsal face of each stipule; plants with axillary short-shoots; perulate bud scales lacking; Greater Antilles and Bahamas only, Calliandra spp. affin. ...............................C. haematommati Bentham 3. Axillary thorns (sometimes at only few scattered nodes); axillary short-shoots only rarely and poorly developed; perulate resting buds present; widespread in seasonally dry continental N. and S. America as well as the West Indies..............Chloroleucon 2. Armament of spinescent stipules. 4. No petiolar nectary.........Zapoteca subgen. Aculeata 4. At least one nectary on each lf-stk, either between or below the first pair of pinnae. 5. Lf-axis broadly green-winged...............Pithecellobium 5. Lf-axes terete or ventrally channeled, not wing-marginate. 6. Specimen in flower: 7. Petiolar nectary exactly interpinnal; venation of lfts pinnate................Pithecellobium. 7. Either the petiolar nectary borne below first (or only) pair of pinnae or venation of lfts palmate. 8. Fl-buds obovoid-pyriform from inception; calyx campanulate 1--3 mm; corolla 3--6.3 mm; androecium 0.65--1.45 cm. 9. First petiolar nectary situated below proximal pair of pinnae; lft-venation pinnate or in smallest lfts simple; capitula not, or not exclusively, arising from brachyblasts.........................Havardia. 9. First petiolar nectary situated exactly between proximal pinna-pair; lft-venation palmate, or in smallest lfts simple; capitula all arising from scaley brachyblasts. 10. Petiolar nectary sessile, shallowly cupular; ovary-stipe 1 mm or longer....... .......................................Painteria 10. Petiolar nectary stoutly stipitate, ñ columnar; ovary-stipe very short....Ebenopsis 9. Fl-buds flasked-shaped, until shortly before anthesis acute or acuminate; calyx cylindro-campanulate 5.5--12.5 mm; corolla 11.5--27 mm; androecium 4--9 cm.. .........................................Sphinga 6. Specimen in fruit: 11. Seeds cupped by a fleshy aril.........Pithecellobium 11. Seeds borne on a filiform or narrowly ribbon- like funicle. 12. Pod ligneous subterete, its cavity divided by interseminal septa; seeds obese, reddish- brown......................................Ebenopsis 12. Pod leathery or papery, laterally compressed, unilocular; seeds otherwise. 13. All or most capitula racemose or paniculate on hornotinous branches...................Havardia 13. All capitula arising from brachyblasts. 14. Pod leathery, strongly recurved; petiolar nectaries interpinnal.........Painteria 14. Pod stiffly papery, straight; petiolar nectaries below mid-petiole..............Sphinga 1. Stems unarmed. 15. Lvs simply paripinnate. 16. Fruit variable in form, compression, and texture, but indehiscent; seeds covered with enlarged, sticky, sweet-tasting hairs; genus of many spp., ubiquitous in Neotropical lowland and low-montane habitat..........Inga 16. Fruit dehiscent through one or both sutures. 17. Inflorescence cauliflorous at least in part; pod plumply compressed, at dehiscence the valves narrowly gaping to release seeds; seeds 3--3.5 cm diam, the testa papery, fragile; e. Amazonian Brazil..........Zygia 17. Units of the inflorescences axillary to lvs; pods compressed, subterete or moniliform, the valves elastically dehiscent and sometimes contorting; seeds (unknown in Calliandra hymenaeodes) 5.5--14 mm in greatest diam; Panama, Costa Rica, n.-w. Colombia, and the Guianas. 18. Lvs lacking nectary; lft-venation of 4 nerves from pulvinule; pod unknown, but presumably plano-compressed and elastically dehiscent through both sutures, the valves straight; known only from the Guianas..............Calliandra hymenaeodes Bth. 18. Lvs with a nectary at insertion of every lft-pair; lft-venation pinnate; pod subterete or moniliform, the fleshy red valves becoming wrinkled and fuscous after dehiscence; Costa Rica, Panama, n.-w. Colombia.....Cojoba rufescens (Bth.) Britton & Rose 15. Lvs bipinnate [caveat: one pair of long pinnae borne on very short primary lf-stk in some spp. of Zygia are easily mistaken for two abruptly pinnate lvs]. 19. Petiolar nectaries wanting......................Calliandra ................................and most species of Zapoteca 19. Petiolar nectary between or below the proximal (or only) pinna-pair. 20. Terminal and axillary resting-buds ovoid, composed of firm, brown, closely imbrictate, striately nerved perules. 21. Specimen in flower: 22. Capitula organized in an efoliate terminal panicle or into efoliate pseudoracemes axillary to coeval lvs, the individual peduncles not subtended by a lf; flowers dimorphic.................... ....................................Blanchetiodendron 22. Capitula either solitary or fasciculate, either in coeval lf-axils or at efoliate nodes anterior to lvs. 23. Stem-growth differentiated into flowerless long-shoots and fertile lateral branchlets often contracted into stemless brachyblasts; fls of each capitulum dimorphic; thornless states of..............................Chloroleucon 23. Stem-growth monomorphic; capitula mostly axillary to a coeval lf; fls of each capitulum monomorphic............................Leucochloron 21. Specimen in fruit: 24. Pod papery planocompressed; seeds discoid, the testa papery-membranous, translucent, exareolate. 25. Fruits terminally paniculate; stipe of pod 4--8 mm...........................Blanchetiodendron 25. Fruits either axillary, or lateral and below annotinous foliage; stipe of pod commonly 0, in L. foederale 1--5 mm.... .......................................Leucochloron 24. Pod firm, compressed but plumply so, varying from straight to falcate to spirally coiled; seeds plump, the testa hard, areolate; thornless state of.................................Chloroleucon 20. No resting-buds, or if such are present their scales either a) not striately venulose, or b) linear-lanceolate and loosely imbricate. 25. Plant obligately and exclusively cauliflorous, the units of inflorescence, whether spikes, or capitula, or congregations of either, arising from defoliate nodes of main trunk or of annotinous and older branchlets, clearly separated from and below all expanded coeval lvs. 26. Calyx 14--20 mm; rare sp. of Surinam and French Guiana...........................Macrosamanea kegelii 26. Calyx much less than 14 mm; widespread....... ..................................................Zygia 25. Plant not, or only in small part, cauliflorous, all or most unit inflorescences borne on stems of the current year, most often subtended by a coeval or early hysteranthous lf, but sometimes at efoliate nodes of young stems, or not infrequently aggregated into lateral efoliate pseudoracemes or efoliate terminal panicles...............................27 27. Specimen in flower. 28. Units of inflorescence evidently racemose or spiciform, the individual fls dispersed along an axis at least 3 cm long. 29. Lvs bifoliolate, the pinnae 1 pair, each unifoliolate; Central American......Zygia confusa Rico 29. Lvs plurifoliolate. 30. Units of inflorescence subtended by a fully expanded coeval lf; native, several spp. of........ ...................................................Abarema 30. Units of inflorescence assembled into a compound panicle; 1 Asiatic sp., cultivated..............Falcataria 28. Units of inflorescence capituliform or cymose- umbelliform, or if spiciform relatively dense and the floral axis less than 2.5 cm. 31. Fls of each unit inflorescence monomorphic. 32. Inflorescence a terminal panicle, efoliate throughout or with an expanded lf subtending only a few proximal secondary axes, the individual capitula ever subtended by a leaf. 33. Lfts of longer pinnae 2--5-jug. and the larger blades 7--13 cm; midrib or lfts gently decurved; gigantic trees of equatorial forest, native...Cedrelinga 33. Lfts of longer pinnae 8--13-jug. and the larger blades 2--5 cm; midrib of lfts straight or slightly curved forward; slender trees of Asiatic origin, planted but only weakly naturalized in Neotropics...............................Albizia procera 32. Inflorescence composed wholly or in large part of axillary units, these consisting either of solitary/ fasciculate capitula or of efoliate pseudoracemes of capitula, then either subtended by a coeval lf or arising at efoliate nodes below (not above) coeval foliage. 34. Bracts subtending individual fls of the capitulum charged on ventral face with a nectary resembling that of lf-stk...................Macrosamanea 34. Bracts without a nectary. 35. Calyx tumidly cylindro-campanulate 20--29 mm; ovaries 2--3 per fl...Macrosamanea macrocalyx 35. Calyx much shorter, not tumid; ovary solitary. 36. Macrophyllidious, the lf-formula ii/1 and larger lfts 1--2 dm........................... .................Zygia ocumarensis nom. provis. 36. Mostly microphyllidious, the lfts commonly more numerous, always much smaller. 37. Receptacle of each unit of inflorescence capitate, globose, or pyriform. 38. Inflorescence precocious, the peduncles arising below and earlier than foliage of the current growing season, either at efoliate nodes of new branches or congregated in efoliate pseudoracemes (3 genera best separated in fruit). 39. Branchlets thickened at the nodes by a prominent buttress under each lf-scar; fruit a craspedium or indehiscent legume ......................................Lysiloma 39. Branchlets terete or nearly so at nodes and buttresses lacking at nodes; fruit either dehiscent, or if indehiscent thick-ligneous and strongly recurved. 40. Stipules cordate; lft-pulvinules 1--3 mm; pod long-stipitate, broad- linear plano-compressed, straight...... ...............................Hesperalbizia 40. Stipules not cordate; lft-pulvinules less than 1 mm; pod sessile, broad- linear, decurved through «--2 circles.. ................................Enterolobium 38. Inflorescence otherwise, the peduncles axillary to coevally expanding or fully expanded lvs; stipules lanceolate, subulate, linear, or 0. 41. Corolla campanulate 42. Pubescence of new growth of white or sordid white, never brown or golden hairs; fruit either a craspedium or an indehiscent legume, the valves not colored internally..................Lysiloma 42. Pubescence of new growth of brown or golden hairs; fruit a pod dehiscent through one or both sutures, the valves internally colored red or orange....... .....................................Abarema 41. Corolla tubular.......................Cojoba 37. Receptacle of unit inflorescences linear or linear-clavate. 42. Pinnae 1-jug.; intrastaminal disc around ovary; local astride Brazil-Bolivia boundary.................................. ........Zygia odoratissima (Ducke) L. Rico 42. Pinnae plurijug.; no intrastaminal disc; cultivated and locally naturalized. 43. Fls pedicellate, the racemes borne in contemporary lf-axils.................. .....................Paraserianthes lophantha 43. Fls sessile, the spikes terminally paniculate.........................Falcataria 31. Fls of each unit inflorescence dimorphic. 44. Lf-formula i/1, all lvs amply 4-foliate; inflorescence paniculate, but most unit inflorescences subtended by a rudimentary lf-stk with nectary. 45. Corolla of peripheral fls of each capitulum 11.5--15.5 mm............................Abarema levelii 45. Corolla of peripheral fls of each capitulum 7 mm or less; few paucifoliate spp. of..............Abarema 44. Lf-formula higher in some respect, all or most lvs at least 8-foliolate. 46. Venation of lfts palmate, or the blade, if very narrow, 1-nerved. 47. Capitula all subtended by a bract and disposed along a simple, terminal, abruptly flexuous axis distal to all expanded lvs of current year...... ...................................Albizia julibrissin 47. Capitula either subtended by a coeval lf, or borne in compound pseudoracemes or panicles, or arising precociously on annotinous branches proximal to foliage of current year. 48. Capitula (either solitary or fasciculate) or efoliate pseudoracemes of capitula arising from the axil of lvs of current year or from efoliate nodes below them. 49. Lfts of longer pinnae 40--80-jug., the longer ones 2.5--6 mm, 1-nerved; ovary truncate at apex............................ .............Enterolobium sect. Robrichia 49. Lfts fewer and larger, palmately nerved; ovary tapering at apex..................... ..........Enterolobium sect. Enterolobium 48. Capitula either all axillary to coevally expanding lvs, or together paniculate above or at least beyond foliage of current year. 50. All capitula subtended by a coevally expanding or early hysteranthous lf (this sometimes reduced distally to a rudimentary lf-stk with nectary); peduncles 3--13 cm; lfts of longer pinnae 4--10-jug. and to 3 cm or more............................Albizia lebbeck 50. Capitula all or most subtended by a bract and disposed in compound panicles above and beyond the foliage; peduncles in most spp. less than 3 cm, if longer then the lfts at least 30-jug. and much smaller. 51. Stipules foliaceous 1--2.5 cm, caducous but at full anthesis some of them usually remaining at proximal nodes of panicle; Asiatic, planted in Neotropics............ ...............................Albizia chinensis 51. Stipules much smaller, or lacking; native...............Albizia sect. Arthrosamanea 46. Venation of lfts pinnate. 52. Ovary truncate; three genera, abruptly differentiated by fruits but not technically separable at anthesis........................... .......Abarema, Balizia, Hydrochorea 52. Ovary tapering at apex. 53. Corolla of peripheral fls at most 7 mm..... .............................................Abarema 53. Corolla of peripheral fls 9--18 mm. 54. Pedicel of outermost peripheral fls of capitulum 11--22 mm..................Pseudosamanea 54. Pedicel of outermost peripheral fls of capitulum 1--9.5 mm........................Samanea 27. Specimen in ripe fruit: 55. Seeds exareolate. 56. Fruit a long papery samariform loment 20--70 x 3.5--6 cm, pinched between the planocompressed, indehiscent articles and at each isthmus twisted through ñ 90ø.....................................Cedrelinga 56. Fruit otherwise, not segmented, dehiscent. 57. Pod diverse in curvature, texture, and compression, but the endocarp internally either red, maroon, or orange-brown, contrasting in color with the ñ translucent, either blue, gray-blue or pale tan (sometimes partly opaque and bright white) seed-testa. ....................................................Abarema 57. Pod and seeds otherwise. 58. Fruit cylindroid, torulose or moniliform, the ripe valves prior to dehiscence red externally, after dehiscence leathery and shrivelled.................Cojoba 58. Fruit ñ laterally compressed, the valves either flat or low-convex, never red externally, not shrivelled after dehiscence..................Macrosamanea 55. Seeds areolate. 59. Venation of lfts pinnate. 60. Pod indehiscent, strongly biconvex or subcylindroid, the continuous valves fibro-ligneous or pulpy, the endocarp at least narrowly septiferous; macrophyllidious, the lfts of longer pinnae 3--9 pairs and (2--)2.5--6 cm. 61. Sutures of pod externally differentiated into prominent broad keels; seeds plumply oblong- ellipsoid, less than 3 times as long as wide...... .................................................Samanea 61. Sutures of pod immersed; seeds narrowly oblong- ellipsoid ñ 3 times as long as wide............... .....................Balizia sect. Leucosamanea 60. Pod not as above, always strongly compressed laterally, but either a) papery planocompressed, or b) leathery and elastically dehiscent, or c) tardily follicular, or d) indehiscent and incipiently lomentiform, and if the cavity divided by interseminal septa the lvs microphyllidious and the longest lfts less than 1.6 cm. 62. Valves of pod continuous. 63. Pod falcately recurved or coiled, the endocarp internally either red, maroon, or orange-brown, contrasting in color with the ñ translucent, either blue, gray-blue, or pale tan (sometimes in part opaque and bright white) seed-testa........ ...............................................Abarema 63. Pod straight or almost so, not red inside; seeds mostly brown. 64. Sutures of pod dilated, framing the transversely fibrous valves; seeds narrowly oblong, ñ 3 times as long as wide............. ......................Balizia sect. Balizia 64. Sutures of pod slender, not forming a raised frame around the valves, sometimes immersed; seeds in profile round or elliptic, nearly isodiametric. 65. Stipe of pod 0--4 mm. 66. Peduncles 2.5--8 cm; valves of pod densely pubescent; native in Centr. America, Cuba and n. S. America........... ...................................Pseudosamanea 66. Peduncles less than 1 cm; valves of pod glabrous; cultivated and perhaps sparingly naturalized in the Neotropics............. .................................Albizia procera 65. Stipe of pod 10--40 mm.............Hesperalbizia 62. Valves of pod tardily segmented between seeds, incipiently lomentiform......................Hydrochorea 59. Venation of lfts palmate, or the lfts very narrow and 1-nerved. 67. Pod at once lignescent and decurved through at least 3/4 circle, often further into a compressed spiral, indehiscent; seeds separated by complete septa. 68. Lfts very numerous, small and narrow, 40--80-jug. in longer pinnae and only 2.5--6 mm long, 1-nerved ...................Enterolobium sect. Robrichia 68. Lfts less numerous and larger, clearly palmate- veined..........Enterolobium sect. Enterolobium 67. Pod straight, not lignescent, commonly but not always inertly dehiscent; cavity continuous, septa lacking. 69. Receptacle of each unit inflorescence elongate, the pedicel-scars well separated along an axis 1.5--6 cm...........................Falcataria mollucana 69. Receptacle of each unit inflorescence globose, shortly oblongoid, or pyriform, the pedicel-scars contiguous. 70. Pod 25--52 mm wide; lfts of longer pinnae 4--10-jug. and the longer ones ñ 3--5 cm, obtuse .......................................Albizia lebbeck 70. Pod 16--26 mm wide, in 2 spp. to 32 mm wide but if more than 25 mm wide then the leaflets much more numerous and smaller. 71. Lfts dimidiate, the midrib forwardly displaced to within 0.5 mm of anterior margin, the apex acute; Asiatic, planted and naturalized in the Americas. 72. Lfts bicolored, pallid beneath; inflorescence of each leafy branch of the season terminal and simple, its primary axis abruptly flexuous; pod inertly dehiscent through both sutures; pleurogram occupying middle of each seed-face.................... ...............................Albizia julibrissin 72. Lfts pallid on both faces; inflorescence of each foliate branch of the season ñ branched; pod falling indehisced; pleurogram small, displaced well below middle of seed- face.............................Albizia chinensis 71. Lfts often inequilateral but not dimidiate, if the midrib much displaced then the apex obtuse; native..Albizia sect. Arthrosamanea