Abarema abbottii
Rupert C. Barneby
38. Abarema abbottii (Rose & Leonard) Barneby & Grimes, comb. nov. Pithecolobium abbottii Rose & Leonard, J. Wash. Acad. Sci. 17: 254. 1927. — "Collected near San Lorenzo Bay, on the south coast of Samaná Bay, Dominican Republic, April 29, 1922, by W. L. Abbott (no. 2258)." — Holotypus, US 1079252!; isotypi, NY!, US!. —Jupunba abbottii (Rose & Leonard) Britton & Rose, N. Amer. Fl. 23: 27. 1928.
Microphyllidious trees 4-12 m with rough gray furrowed bark, the young branches densely, the lf-axes and inflorescence more thinly furfuraceous-puberulent with incurved, brownish or sordid hairs <0.2 mm, the crowded subsessile, commonly subopposite lvs strongly bicolored, the firm, ventrally convex lfts bright green (when dry dark brown) glabrous and lustrous above, beneath pallid dull and glabrous except for a tuft of hairs in anterior basal angle of midrib, the subumbellate capitula of white fls borne solitary in few distal lf-axils, immersed in foliage. Stipules 0 (no scars seen). Lf-formula of adult fertile branches iv—vi/8—12 (of some sterile branches, no further described, to x-xi/13); lf-stks 2-6 cm, low-convex dorsally, narrowly ridged and grooved ventrally, shallow-sulcate laterally, the true petiole almost 0 (and pulvinus obscurely differentiated), the longer interpinnal segments 7—12(—14) mm; petiolar nectaries sessile or almost so, cupular thick-rimmed 0.3-0.7 mm diam, lacking between first and often between second pair of pinnae but always present distally, smaller nectaries between some distal lft- pairs; pinnae decrescent at each end of lf-stalk but more abruptly so distally, the longer ones 2-4 cm, the longer interfoliolar segments 2.5-5 mm; lft- pulvinules in dorsal view 0.2-0.4 mm; lfts sessile against pinna-rachis, a little decrescent proximally but otherwise subequiform, the blade oblong-obovate or broadly oblong-elliptic from inequilateral broad- cuneate base, broadly rounded at apex, the longer ones 5—8.5(—10) x 3-5 mm, (1.4—)1.5-2.2(-2.5) times as long as wide; the straight subcentric midrib depressed ventrally, prominulous dorsally and there giving rise on each side to 2-3 weak secondary venules faintly brochidodrome within the revolute margin, tertiary venulation fully immersed. Peduncles more or less compressed (1-) 1.5-4 cm; capitula ±20-30-fld, the terminal fl sometimes sessile and a trifle larger but its androecium scarcely modified, the receptacle narrowly clavate 2-3 mm long; bracts subulate 0.4—0.9 mm, puberulent, caducous; proximal pedicels 2-4 x 0.4 mm, the distal ones either nearly as long or progressively shorter; perianth 5-merous, externally glabrous except for microscopically ciliolate calyx-teeth and thinly puberulent corolla-lobes; calyx turbinate-campanulate 2.2-3 x 1.4-1.8 mm, the depressed-deltate teeth 0.2-0.3 mm; corolla 6-7 mm, the ovate lobes 1.8-2.5 x 1-1.3 mm; androecium 27-36-merous, the longest filaments 16-21 mm, the stemonozone 0.6-1 mm, the tube 2.5-4 mm; ovary glabrous truncate. Pods usually solitary, subsessile but narrowed into a basal neck, the body in profile undulately linear, 5-8 x 0.8 cm, evenly recurved through a full circle, to 12-seeded, the prominent sutures <1 mm wide, the thinly leathery, fuscous glabrous, venulose valves low-convex over each seed, the endocarp dull chestnut-red; seeds described as blue (not seen mature), on a coiled funicle, pleurogram complete.
In broadleaf woodland on limestone, ranging from near sea level up to 800 m, localized in NE Dominican Republic, around the S shore of Samaná Bay and W into Sa Quita-espuela, in depts. Samaná and El Seibo. — Map 30. — Fl. IV-VII.
Abarema abbottii is closely related to A. oppositifolia, of which it could be interpreted as a subspecies modified in response to a xeric environment. Smaller, more crowded leaves, leaflets fewer by a few pairs, suppression of the petiolar nectary, slightly smaller flowers, and endocarp pigmented overall are the weak morphological criteria that coincide with its allopatric dispersal in northeastern Hispaniola.
References: [Article] Barneby, Rupert C. & Grimes, James W. 1996. Silk tree, guanacaste, monkey's earring: a generic system for the synandrous Mimosaceae of the Americas. Part I. Abarema, Albizia, and allies. Mem. New York Bot. Gard. 74: 1-292.