Key to the Native and Naturalized Genera of Ingeae
(Leguminosae: Mimosoideae) in the Neotropics

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