Inga microphylla Humboldt & Bonpland ex Willdenow, Sp. Pl. 4: 1004. 1806. — "Habitat in Cumana [Sucre, Venezuela]." — Holotypus, B-WILLD 19007, seen in microfiche; isotypus, Humboldt & Bonpland 118, P-HBK!. — Pithecolobium microphyllum (Humboldt & Bonpland) Bentham, London J. Bot. 3: 200. 1844.

Mimosa guadalupensis Persoon, Syn. Pl. 2: 262. 1806. — "Hab. ad Guadalupam." — Holotypus, P-JUSS!. — Inga guadalupensis (Persoon) Desvaux, J. Bot. 3: 70. 1814. — Equated with Pithecellobium unguis-cati by Bentham, 1875: 573; & by Duss, Fl. Phan. Antill. Fran?. 254. 1897.

Pithecolobium oblongum Bentham, London J. Bot. 3: 198. 1844. — "Western coast of Columbia [Panama], Cuming, n. 1155, Sinclair." — Lectotypus, Cuming 1155, K (hb. Bentham.)! = NY Neg. 2040. — Feuilleea oblonga (Bentham) O. Kuntze, Revis. Gen. Pl. 1: 188. 1891.

Feuilleea unguis-cati var. latifolia O. Kuntze, Revis. Gen. Pl. 1: 184. 1891. — "Barbadoes." — Holotypus, O. Kuntze 706, NY!.

Pithecolobium flavovirens Britton, Bull, New York Bot. Gard. 3: 442. 1905. — "[Bahama Is.] Sheep Key, Inagua (Nash & Taylor, 1143)." — Holotypus, NY!. — Equated with P. unguis-cati by Britton & Millspaugh, Bahama Fl. 155. 1920.

Pithecolobium seleri Harms, Feddes Repert. Spec. Nov. Regni Veg. 16: 350.1920. — "Mexico: Oaxaca... zwischen Tequisistlan und Jalapa (Seler no. 1686—Jan. 1896)." — Holotypus, †B.

Pithecollobium pulchellum Pittier, Contr. U.S. Natl. Herb. 20: 462. 1922. — "Culiacán, Sinaloa, Mexico, by T. S. Brandegee, August 25, 1922." — Holotypus, US!.

Pithecollobium paniculatum Pittier, Contr. U.S. Natl. Herb. 20: 462. 1922. — "... at San Gerónimo, Oaxaca, Mexico, December 9, 1906, by C. B. Doyle (no. 36)." — Holotypus, US 674696!.

Pithecolobium microstachyum Standley, J. Wash. Acad. Sci. 13: 439. 1923. — "Type . . . collected . . . near La Union, Salvador . ! . February, 1922, by Paul C. Standley (no. 20646)." — Holotypus, US 1136477!; isotypus, NY!.

Pithecolobium microchlamys Pittier, Bol. Ci. Técn. Mus. Com. Venez. 1: 48. 1926. — ". . . alrededores de Bar- quisimeto, Lara [Venezuela]; flores Septiembre 19, de 1923 (Pittier 11 188, tipo)." — Holotypus, VEN n.v.; isotypi, NY!, US 118187!.

Pithecellobium pittieri Britton & Killip, Ann. New York Acad. Sci. 35: 125. 1936, based on P. oblongum sensu Pittier, Contr. U.S. Natl. Herb. 20: 463. 1922; non Bentham, 1844. — "[Colombia.] Santa Marta, H. H. Smith 28a" — Holotypus, GH!; isotypi, NY!, US 532717!.

Pithecollobium pulchellum Pittier, Bol. Soc. Venez. Ci. Nat. 4: 82. 1937. — "[Venezuela.] Lara: Cabeceras del río Chorro, cerca de Carora; fl. Novembre 1937 (Esteban Delgado 37, tipo)." — Holotypus, VEN (?) n.v. — Pithecellobium larensis [sic] Cardenas, Revista Fac. Agron. (Maracay) 7: 123. 1974, a legitimate substitute; non P. pulchellum Pittier, 1922.

Pithecolobium saxosum Standley & Steyermark, Publ. Field Mus. Nat. Hist. 23: 163. 1944. — "Guatemala: Dept. Chiquimula . . . above Chiquimula, on the road to Zacapa . . . October 14, 1940, Paul S. Standley 74367." — Holotypus, F, not available for study in 1991 = F. Neg. 55085!; paratypi, Standley 73726, 74195, F n.v.

Acaciae quidammodo accedens . . . jamaicensis spinosa, bigeminatis foliis Plukenet, Phytographia 1, fig. 6. 1691; Almagestum 93, t. 82, fig. 4. 1696.

Acacia arborea major spinosa, pinnis quatuor . . . Sloane, Voy. Jamaica 2: 56. 1725.

Mimosa foliis bigeminatis Linnaeus, Hort. Cliff. 207. 1737. Acacia quadrifolia, siliquis cincinatis vulgo Bracelets Plumier ed. Burman, Pl. Amer., fasc. prim. 2, tab. 4. 1755. Mimosa unguis-cati sensu Jacquin, Pl. Hort. Schoenbr. 3: 74, t. 392. 1798.

Pithecellobium [variably spelled] unguis-cati sensu Bentham, 1875: 573, syn. M. rosea et M.forfice exceptis; Sargent, Silva 3: 133, t. 145. 1892; Fawcett & Rendle, 1920: 146; Standley, 1922: 394; Britton, 1924: 348; Britton & Rose, 1928: 21; Adams, 1972: 332; Isely, 1972: 286; Isely, 1973: 116, map 40 (Florida); Little, Trees Puerto Rico 2: 365, t. 365. 1974; Correll & Correll, 1982: 681; Liogier, 1985: 65; McVaugh, 1987: 238, fig. 32.

Macrophyllidious, semi- or fully deciduous, arborescent shrubs and 1-several-tmnked trees 1—7(—10) m, the stiff, brown or fuscous branchlets randomly armed at nodes with spinescent stipules (but flowering branchlets often unarmed), either glabrous except for sometimes minutely puberulent fls or variably strigulose or pilosulous throughout, the exactly 4-foliate lvs dull olivaceous, a little paler beneath, the inflorescence composed of short, terminal or axillary, mostly efoliate pseudoracemes of capitula or short spikes, either immersed in foliage or shortly exserted. Stipules when modified into spines either horizontal or widely ascending, 3-17 mm, but many or all compressed- conical or subulate ±0.5-1.5 mm, with indurate, more or less burnished tip, all nearly always long-persistent. Lf-formula i/1; lf-stk of major lvs 6-30(-36) mm, at middle 0.4—0.9 mm diam, that of reduced upper lvs often shorter, the ventral sulcus shallow and open; a sessile or shortly stoutly stipitate, cupular thick- rimmed nectary 0.3-0.8(-1.2) mm diam borne at tip of lf-stks and a similar but smaller one between each pair of lfts; rachis of pinnae (1.5-)3-16 mm, either linear or a little dilated distally; pulvinule of lfts (0.4-)0.6-1.7 x 0.3-1.2 mm, wrinkled; lfts variable in size and outline, asymmetrically obovate-suborbicular or obovate-elliptic to oblong-oblanceolate or -elliptic from inequilateral base, obtuse or shallowly emarginate (exceptionally apiculate), the longer ones (1.5—) 1.7—5(—6) x 0.8-4.5 cm, 1.1—2 times as long as wide; venation pinnate, the only slightly excentric midrib forwardly incurved and giving rise on each side to (3-)4-7 secondary nerves brochidodrome well within the plane margin, and thence to sinuous tertiary and reticular venules either delicately prominulous on both faces or (especially in age) depressed on upper face and prominulous beneath. Primary axis of pseudoracemes 1-13 cm; peduncles solitary (very exceptionally and randomly geminate), the lowest commonly subtended by stipules and a rudimentary lf-stk with nectary, some median ones by 3 bractlets, the uppermost by a single bract, the longest of any inflorescence 1-3 cm; capitula or spikes 8-23(-35)-fld, the receptacular axis l-30(-35) mm; floral bracts ovate or lanceolate ±0.7-1.2 mm, incurved, persistent; fls sessile homomorphic, the usually greenish perianth 5(-6)-merous, either glabrous, or silky-strigulose, or less commonly pilosulous, the filaments either white, or ochroleucous, or pink-tinged either throughout or only toward base and pallid distally (never dark red- purple); calyx submembranous campanulate or turbinate-campanulate 1-2.6 x 0.8-2.6 mm, weakly or sharply 5-nerved, the depressed-deltate or triangular teeth 0.15-0.4 (-0.6) mm; corolla funnel-shaped usually 3-6.5(-7) mm, in NW Venezuela locally 7-9 mm, the ascending or seldom subrecurved lobes 0.7-1.8 mm; androecium (21-)22-34(-36)-merous, (8—)9—19 mm, the stemonozone 0.65-1 mm, the tube (1.8-) 2-7.5 mm; ovary at anthesis glabrous or less often micropapillate, the stipe (0.4-)0.6-3 mm, the body (1.2-) 1.4—2.4 mm. Pod pendulous, in profile sinuously linear, recurved through (2/3-) 1-2 circles and often also randomly twisted, compressed but plumply biconvex over seeds, when well fertilized (6—)7—17 (-20) x 0.7-1.4 cm, (6-)7-12(-14)-seeded, attenuate at base, apiculate, the almost immersed sutures either shallowly or deeply recessed between seeds, the thinly fleshy, glabrous or strigulose-pilosulous, red or red- brown valves becoming dry, stiffly leathery, externally fuscous, the endocarp orange overall; dehiscence through both sutures, the valves gaping and coiling; arilloid funicle white, pink, or red, nidulating 1/3-2/3 of the seed; seeds plumply lentiform or subreniform, in broad view 6-10 x 5-8 mm, the testa crustaceous, lustrous black, the pleurogram subcircular.

In deciduous or semideciduous, seasonally dry woodland and scrub communities, from sea level to 550 (in Oaxaca reported from 1500) m, widely dispersed in tropical Mexico, Central America, West Indies and N South America, introduced elsewhere: in Mexico on the Pacific coast and foothills from extreme SW Sonora to Chiapas and on the Gulf slope S from N Tamaulipas to Yucatán Peninsula, thence interruptedly SE to Panama; Bahama Is. S from Eleuthera; throughout the Greater and Lesser Antilles, but apparently rare in Cuba, only planted in Barbados; naturalized on the keys and the coast of SW peninsular Florida, and in Bermuda; in South America along the Caribbean coast and in the drier interior hill country from N Colombia across Venezuela to Trinidad and Tobago, known from S of the Orinoco by one collection from NE state of Bolívar; once collected in Guyana, perhaps only in cultivation. — Map 6. — Fl. most prolifically after rain, with new foliage, but sporadically at other times, and in N-centr. Venezuela often from leafless annotinous branches. — Conchi, guayacán, mongollano, rolón, uña-de-gato (Mexico and Central America); cinazo (Hispaniola); black-bead, bread-and-cheese, crab- pickle (former British colonies); platanito, taguapire (Venezuela).

We here adopt a broad definition of P. unguis-cati, different from that of Bentham (1875: 573) insofar as P. roseum is excluded, but expanded in another direction to include P. oblongum, and in effect coextensive with the definition proposed by McVaugh (1987: 238, fig. 32). It accommodates numerous segregates proposed by Britton, Harms, Pittier, and Standley, most of which were described either from a single collection or from few collections from one locality and have not been evaluated subsequently. As now understood, P. unguis-cati differs from P. roseum and P. dulce in predominantly solitary peduncles, further from P. roseum in almost always shorter, always paler filaments, and further from P. dulce either in longer peduncles, or longer flowers, or glabrate perianth, or spicate flowers, or glabrous ovary, or by some combination of those features. The pods and seeds of these three species are essentially alike, varying in each in width and vesture, and with width in size of seeds, but not in any distinctive pattern.

Infraspecific variation in P. unguis-cati sens. lat. is complex. Features that have been thought diagnostic, or that might yet appear to be so, turn out on analysis to be without exception independently variable, so that segregation of infraspecific taxa by a syndrome of characters has become more difficult, not less so, as herbarium material has accumulated. The potential taxonomic characters and their dispersal within the species may be described as follows:

1. Stature. Normally arborescent and amply leafy, the species is represented in barren habitats by low shrubby, commonly microphyllidious populations. These seem independently derived and collectively do not constitute a natural unit. The so-called P. microphyllum dominant along the desert coast of Venezuela is mimicked by xero-morphic populations on Puerto Rico (e.g., Heller 1005, 4602 NY, from Fajardo), on the Pacific lowlands in Mexico (e.g., Rose, Standley & Russell 13301, NY, US) and in El Salvador (e.g., Standley 20891, NY).
2. Armament. As in other Ingeae with spinescent stipules, spiny branches of P. unguis-cati often give rise to unarmed flowering branchlets. This pattern of variation was known to Linnaeus in cultivation and is prevalent in the wild. However striking to the eye, armament offers no reliable taxonomic criteria.
3. Pubescence. The leaflets vary from glabrous to thinly pilosulous on the petiole only, and by intermediate states to softly pilosulous overall, while the perianth varies from glabrous overall to pilosulous overall, but is most commonly ap- pressed-silky either overall or only on the lobes. Leaflets wholly glabrous or glabrous except for a tuft of hairs in one basal angle of midrib are dominant in the species and universal in the West Indies. Pubescent leaflets are commonest on the Pacific slope in North America and occasional in northern South America. Excessive value has been attached to leaf-pubescence not only in P. unguis-cati but also in P. roseum, for it is imperfectly correlated with other variable features and poorly so with dispersal. McVaugh (1987: 240) has noted that glabrous and pubescent leaves occur in the same population in Nueva Galicia, and H. H. Smith, in a field-note on his number 698 (NY), records glabrous and pubescent leaves on the same plant. The perianth is generally more densely pubescent in continental North America than in the West Indies and becomes pilosulous, rather than strigulose, only on the Pacific coast. Variation in pubescence of the flowers is, however, continuous. We regard P. seleri, P. paniculatum, and P. saxosum as no more than variously pubescent analogues of glabrate P. oblongum, and collectively different from West Indian P. unguis-cati only in tendencies toward elongation of the raceme-axis and shortening of the filament-tube and stipe of ovary.
4. Unit of inflorescence. The receptacular axis varies from very short, yielding a more or less hemispherical capitulum of close-packed florets, to distinctly elongate, giving rise to an ellipsoid capitulum, or to a spike with some proximal or sometimes all florets well separated. Here again, transitional states are frequent, and even on Jamaica the receptacle varies from 1 to 8 mm in length.
5. Calyx. The calyx varies from shallowly to deeply campanulate or occasionally to turbinate-cam- panulate, but independently of other characters and randomly in range.
6. Corolla. This varies in length from 3 to 7 mm. Its lobes commonly remain erect through anthesis, but rarely curve outward. Size of the corolla appears to be more or less stabilized in extensive populations, but as it fluctuates independently of other variable features its value was evidently overemphasized by Pittier.
7. Androecium. This varies in total length, and independently of total length in length of tube, which is proportionately shorter overall in Mexico and Central America (mostly 3 mm or less) than in the West Indies (mostly 3-7 mm), but randomly variable in Venezuela.
8. Gynoecium. The ovary at anthesis varies from perfectly smooth to papillate under magnification (x40) or thinly minutely puberulent (especially beyond middle), and the papillae after fertilization often develop into trichomes. Thus, an apparently glabrous ovary may give rise to a densely puberulent fruit. Populations with pubescent leaves seem more likely than those with glabrous leaves to have puberulent ovaries, but this is not invariably true.

   From our survey of the whole macromorphological variation in P. unguis-cati sens. lat. we recognize these general geographic trends: (1) in Mexico, on both the Pacific and Gulf slopes, and in Central America, toward dorsally tufted or variably pubescent leaflet-blades, elongation of the capitulum into a spike, a relatively short filament tube, and short ovary-stipe; (2) in the West Indies, to glabrous leaflets, condensed capitula, long filament tube, and relatively long ovary-stipe; and (3) in Colombia and Venezuela perplexing arrays of these characters, which effectively preclude definition of taxa above the populational level. The possibility that some of the variation recorded in P. unguis-cati may be attributed to introgressive hybridization with sympatric P. dulce or P. roseum, or both, requires study in the field.