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
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