Monographs Details: Abarema gallorum Barneby & J.W.Grimes
Authors:Rupert C. Barneby
Authority: 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.
Description:Latin Diagnosis - A. floribundae, quacum legumine exacte quadrat, affinis, ab ea foliorum amplissimorum formula i- iii/4-5 (nec iii-vi/8-21) primo intuitu diversa, ab A. jupunba var. trapezifolia, sympatrica et pinnarum foliolorumque numeris congrua, foliolis maximis (5-8 cm usque longis) dorso subglabris necnon leguminis magni latioris 12.5-16 x 2.1-2.4 (nec 6 9.5 x 1-1.6) cm endocarpio tantum ad seminum loculos colorato, inter semina ochraceo, ut videtur distantior.
Species Description - Amply macrophyllidious, unarmed trees attaining 20(-?) m with trunk 2-3.5 dm dbh, the branchlets, lf- axes, and especially the axillary lf-buds densely tomentulose with sordid gray or brown hairs to 0.15-0.3 mm, the foliage bicolored, the lfts when dry stiffly papery, lustrous dark brown-olivaceous and glabrous above, beneath paler dull and remotely microscopically strigulose, the capitula solitary or fasciculate by 2-4 in coeval lf-axils. Stipules (few seen) lanceolate ±4-4.5 mm, caducous. Lf-formula i-iii/4- 5; lf-stks mostly 4-18 cm, the petiole 2-5 cm, at middle ±1.5-3 mm diam, shallowly narrowly sulcate ventrally, the one or the longer interpinnal segment 2.5-6.5 cm, but in some distal lvs with geminate pinnae the petiole only 1-2 cm; nectaries immediately below each pinna-pair sessile, round or scutiform, plane or shallowly concave, the first one 1.5-2.3 mm diam, the rest scarcely smaller, shallowly cupular, round or elliptic and below all but 1-2 proximal pair of lfts of each pinna-rachis; pinnae when more than one pair distally accrescent, the rachis of furthest pair 5.5-13.5 cm, the longest interfoliolar segment 1.5-4 cm; lft-pulvinules 1.6-2.8 x 0.9-1.4 mm, discolored, grossly cross-wrinkled; lateral lfts oblong around a diagonal, slightly porrect midrib, at base very inequilaterally rounded, at apex broadly obtuse and evidently or incipiently emarginate, the blades of the penultimate pair ±4-8 x 2-3.5 cm, 1.9-2.5 times as long as wide, the terminal pair of lfts broadly elliptic obtuse ±5-8.5 cm; the major secondary nerves ±9-15 on each side of midrib, nearly straight and widely ascending to anastomosis close within the plane corneous margin and connected by random 3- and 4-nary venules, the whole venation sharply finely prominulous on both faces. Peduncles 2.5-7.5 cm; receptacle obovoid, including short terminal pedestal 2.5-5 x 2-3.5 mm; bracts minute caducous; fls dimorphic, the pedicel of lower peripheral ones to ±1.2 x 0.6 mm, that of terminal fl or of several subterminal ones 0, the perianth of all densely minutely brownish silky-puberulent; PERIPHERAL FLS: calyx campanulate, narrowed into pedicel, 4.2-5 mm, the ovate teeth 0.4-0.9 mm; corolla pinkish, ±8 mm, the erect lobes 2-2.4 mm; androecium 26-32-merous, the stemonozone 1-1.2 mm, the tube 4.5-5.5 mm, the tassel pink, expanded at nightfall; nectarial disc 0; ovary oblong, a little dilated and abruptly truncate at puberulent apex; TERMINAL FL: calyx ±6 mm; corolla 11-12 mm, the lobes ±2.5 mm; androecial tube a little longer than corolla. Pods solitary, undulately broad-linear and falcately retro-arcuate, 11-16 x 2-2.4 cm, contracted at base into a short pseudostipe and at apex into a short cusp, 10-14-seeded, the leathery, almost plane, fuscous glabrous evenulose valves framed by prominent sutures 1.5-2 mm wide, the endocarp smooth, brown in each seed-cavity, tan in between; dehiscence through both sutures, the valves randomly twisted; funicles linear compressed, sigmoid distally; seeds unknown.
Distribution and Ecology - In virgin forest at low elevations, known only from N French Guiana: in the Sinnamary basin at 53°W, 5°20'N; and in the Arataye basin at Station des Nouragues near 52°42'W, 4°3'N. - Map 8. - Fl. VIII-IX.
Discussion:Abarema gallorum has the pink filaments, truncate ovary, and broad pod with endocarp mottled brown and tan that characterize A. floribunda and A. ferruginea, but is distinguished by the low number and great size of the leaflets. The almost sympatric A. jupunba var. trapezifolia is similar in leaf-formula, but differs in somewhat smaller flowers, white filaments, ovary tapering into the style, and a narrower pod (<1 cm, not 2-2.4 cm wide) uniformly orange inside. Gigantic shade-leaves (Grimes 3338, ex parte, NY) have leaf-stalks to 6.5 dm, pinna-rachises to 4 dm, and leaflets to 8 cm in length.
Distribution:French Guiana South America