Abarema adenophora

Rupert C. Barneby

15. Abarema adenophora (Ducke) Barneby & Grimes, comb. nov. Pithecolobium adenophorum Ducke, Arq. Inst. Biol. Veg. 4: 5. 1938. — "[Brazil, Amazonas:] ... sat frequens circa Manáos . . . loco Estrada do Aleixo 15-6-1932 leg. A. Ducke (H[erb.] J[ardim] B[otânico do] R[io de Janeiro] 23.238." — Holotypus, RB (2 sheets, fl. & fr.)!; isotypi, NY!, P!,U(2)!,US!.

Pithecolobium adenophorum sensu Ducke, 1949: 36.

Macrophyllidious trees 12-30 m with trunk 2-5 dm dbh, the fuscous annotinous branches with epidermis exfoliating in flakes, the mature foliage appearing glabrous but the young branches, petioles and inflorescence densely minutely furfuraceous-puberulent with gold-brown or sordid hairs 0.1 mm or shorter, the bicolored lfts sublustrously brown-olivaceous above, paler beneath, the inflorescence a short terminal panicle of pedunculate, dense and short racemes of greenish white fls arising either singly or geminate from the axil of coevally expanding or quickly hysteranthous lvs, the fruits immersed in foliage. Stipules caducous from emergent lvs, linear 1.5-5 mm, absent from mature spms. Lf-formula ii—iii(—iv)/2—4(—5), the lfts 16-40(-48) per If; lf-stks 4.5-33 cm, the petiole proper 2.5-10 cm, the longer (or only) interpinnal segment 2-11.5 cm; a stipitate or sessile, funnelshaped nectary to 8-13 x 6-12 mm, yellowish when fresh but when dry coriaceous, brown and vertically striate, situated at insertion of first pinna-pair, and often but not always similar but smaller or squatly tube-shaped ones at tip of some pinna-rachises; pinnae of unequal length, the proximal pair shortest, either the distal or the penultimate pair longest, the rachis of these (4—)5—12 cm, its one or its longest interfoliolar segment 1.8-5 cm; paraphyllidia present on nascent pinnae and to 0.7-1 mm, but early caducous from a minute conic protuberance at base of mature ones; lft-pulvinules viewed from dorsal side 2-5 x 1-2.2 mm, closely cross-wrinkled; lfts subequiform but strongly accrescent distally, asymmetrically obovate (or some obscurely rhombic-obovate) from inequilateral, broad-cuneate or rounded base, obtuse muticous or shallowly emarginate, the furthest pair ±5-11 x 3.5-7.5 cm, 1.4-1.8 times as long as wide; the subcentric or moderately displaced midrib evenly arched forward, the close rank of secondary veins widely ascending, brochidodrome well within the incipiently revolute margin, all these and the reticulum of minor veinlets prominulous on both faces but more sharply so beneath. Peduncles strongly compressed 2.5-6 cm; racemes (10-) 15-25-fid, the slenderly clavate receptacle 2-9 mm; bracts evanescent; fls strongly dimorphic, the lower peripheral ones slenderly pedicellate and greenish, the terminal one substantially stouter, sessile on a short pedestal, and white, the perianth of all 5-merous and brownish puberulent externally; PERIPHERAL FLS: pedicels 4.5-6 x 0.5-0.7 mm; calyx 1.6-3 x 1.5-2.2 mm, the ovate-deltate teeth 0.5-0.9 mm; corolla 3.7-5.5 mm, the lance-ovate, apically cucullate lobes 1.2-2.2 mm; androecium 15-17- merous, ±14—15 mm, the tube (including stemonozone) 2-2.9 mm; TERMINAL FL: calyx 3-5 x 2-2.5 mm; corolla 7-9 x ±2 mm; androecial tube nearly as long as the corolla, the filaments at point of separation dilated and recurved, as in Abarema leucophylla; ovary truncate, pubescent on distal half. Pods in profile undulately linear but coiled into a ring ±3-3.5 cm in external and ±1.5 cm in internal diam, 6-9-seeded, cuneately contracted at base into a short stipe, obscurely apiculate, the stiffly coriaceous valves at broadest point 9-14 mm wide, low-convex over seeds and there ±0.3 (the crustaceous endocarp ±0.05) mm thick, externally fuscous glabrous venulose, within smooth atrocastaneous or tan, but the seed-cavities then slightly darker and lustrous; dehiscence of Abaremat; funicle ribbonlike; seeds (not seen fully mature) pallid, the transparent unwrinkled testa loosely investing the forming embryo, pleurogram 0.

In non-inundated equatorial forest at 40-220 m, of highly discontinuous (known) dispersal between 6°N and 6°S latitude in South America: centr. Amazonia in states of Amazonas (Manaus; lower Madeira basin) and W Pará (Trombetas basin); Huallaga Valley in Alto Amazonas of dept. Loreto, Peru; on Río Atrato in depts. Chocó and Valle, Colombia; disjunct in the lowlands of NE Nicaragua (Zelaya). — Map 17. — Fl. V-VI(-?).

In overall aspect and leaf-formula A. adenophora resembles A. microcalyx, but differs not only in the hypertrophied petiolar-nectaries but in the much larger central flower of the capitula. The fragmented dispersal of A. adenophora might suggest that more than one taxon lies concealed among the disjunct populations, disguised by the prominently modified nectaries, but we have found nothing in their gross morphology to substantiate this possibility. The one other abarema with similarly enlarged nectaries, A. macradenia, differs greatly in leaf-formula and ligneous fruit.

A leaf from a stump-sprout collected near Manaus (Grimes 3118, NY) has these dimensions: leaf-stalk 4.6dm; rachis of furthest pinnae 1.9 dm; largest leaflets 12.5-7 cm. An anomalous fruiting collection from the Ducke Reservation at Manaus has poorly developed leaf-nectaries on the primary leaf-stalk but typical cupular ones on the pinna rachises.

A gigantic leaf collected in Zelaya, Nicaragua (Little 25315, US), under the same vernacular name, grano del oro, as Little’s fertile no. 25427 (US) is another example of vigorous sapling growth: lf-formula vi/6; lf-stalk ±4.5 dm, rachis of longer pinnae to 1.6 dm, terminal lfts to 7 x 4 cm. Yet another, (Poveda 1038, F, from Costa Rica-Nicaragua frontier) perhaps conspecific, has lf-formula v/6, lf-stalk 7 dm, with rachis of larger pinnae 2.3 dm. These measurements are not introduced into the description of the species.

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.