Monographs Details: Pithecellobium x bahamense Northr.
Authors:Rupert C. Barneby
Barneby, Rupert C. & Grimes, James W. 1997. Silk tree, guanacaste, monkey's earring: A generic system for the synandrous Mimosaceae of the Americas. Part II. , , and . Mem. New York Bot. Gard. 74: 1-149.
Synonyms:Pithecellobium x bahamense Northr., Pithecellobium mucronatum Britton
Description:Species Description - Shrubs ±1-3 m, in coppice diffusely branched but densely so, and of rounded outline in open places, either armed or not and either glabrous throughout or the young growth puberulent and the perianth finely silky, intermediate in foliage and size of nectaries between P. keyense and P. histrix. Stipular spines commonly 2-8 mm, or mostly reduced to appressed triangular blades 1 mm or less. Lf-formula either i/1 in all lvs, or i/1-2 in some lvs or in one pinna of some lvs, the lfts hence 4,6, or 8 per lf; petioles 1.5-10 mm, near apex 0.4-0.85 mm wide; lfts obovate or oblanceolate, either obtuse muticous (emarginate), or obtuse deltately apiculate, or abruptly mucronulate by excurrent midrib, the spinule at most 0.8 mm, the largest blades (10-) 12-35 x 4-16 mm; venation of small-lvd P. keyense. Inflorescence of P. keyense, the peduncles (1-) 1.5-5.5 cm, the receptacle 1.5-5.5 mm; fls extremely diverse in length and proportions, the perianth either glabrous or minutely silky-puberulent; calyx campanulate 1.5-3.1 x 0.8-1.3 mm, the triangular- subulate or deltate teeth 0.15-0.5 mm; corolla (3.5-) 3.8-8 mm, the lobes either erect or widely ascending; androecium 18-28-merous, 11-18 mm, the tube 1.6-6 mm, the free filaments pink or red, when relatively short much surpassed by the style; ovary glabrous (micropapillate), the oblong body 1.6-1.9 mm, the stipe as long or slightly longer, 1.8-3.1 mm. Pods of P. keyense, sometimes fewer-seeded.
Distribution and Ecology - In coppice, at savanna margins, and in barren ground along and near the beach, below 50 m, sym- patric with one or both parents in the central Bahamas (Andros, New Providence, Exuma, and Long Island) and along the keys of N Cuba (Matanzas, Camaguey, E to border of NW Oriente). — Map 3. — Fl. sporadically throughout the year
Relationships - We have no experimental evidence that P. x bahamense consists of hybrids derived from P. keyense and P. histrix, although the evidence from morphology and dispersal is persuasive. The supposed hybrids resemble P. keyense in random quadrifoliolate pinnae and in the nectary (almost always) at tip of each pinna, but differ in the mucronulate leaflet-tips (Fig. 1, no. 6). Pithecellobium x bahamense resembles P. histrix, the other putative parent, in diminished foliage, which is, however, variable. The characters by which the parent species differ from one another appear in a series of intermediate states in the hybrids. The flowers of P. histrix are relatively few per capitulum and relatively long, with filaments united into a tube 6-9.5 mm long, whereas those of P. keyense are relatively short, with tube not over 3.5 mm long. In P. x bahamense the corolla is extremely variable in length, and the gynoecial tube varies from 1.6 to 6 mm. With one exception, the hybrid occurs on islands or keys from which both parents have also been collected, the exception being Long Island, from which P. keyense, but not P. histrix, is definitely known. Moreover, the hybrid has no known independent range. It is implausible that three related species, so similar in leaf-formula, flower structure, and fruits, could coexist in one place, such as Mastic Point on Andros, and maintain their genetic identity.
South Andros Bahamas South America
| New Providence Bahamas South America
| Exuma Bahamas South America
| Long Island Bahamas South America
| Matanzas Cuba South America
| Camagüey Cuba South America
| Las Tunas Cuba South America
Common Names:Ram’s horn