Abarema jupunba

Title

Abarema jupunba

Author(s)

Rupert C. Barneby

Scientific Name

Abarema jupunba (Willd.) Britton & Killip

Description

13. Abarema jupunba (Willdenow) Britton & Killip, Ann. New York Acad. Sci. 35: 126. 1936. Acacia jupunba Willdenow, Sp. Pl. 4: 1067. 1806. —Typus infra sub var. jupunba indicatur.

Either macro- or microphyllidious trees (3—)5—35 m (in upland Guayana sometimes small bushy trees 1.5-3 m) tall with smooth gray trunk attaining a mature girth of 2-8(10) dm dbh, the young stems, lf- axes, and inflorescence densely golden-brown- or sordid-tomentulose or -puberulent with spreading- incurved or subappressed hairs to ±0.1-0.3 mm, glabrescent in age, the lvs bicolored, the lfts on upper face glossy dark green, often purplish speckled or mottled and (except for sometimes ciliolate costa) glabrous, beneath pallid-papillate dull and either minutely strigulose overall, the compact, sometimes subspicate or sub-racemose, always short capitula of whitish or greenish, white-stamened, commonly fragrant fls axillary to coeval lvs, immersed in foliage. Stipules linear or linear-lanceolate or elliptic 1.5-6 x 0.4-0.7(-l) mm, early deciduous from a small pallid scar. Lf-formula i-v (in juvenile lf —vii)/3—10(— 12); lf-stk of major lvs associated with fls 2.5-11 (-18) cm, of var. trapezifolia (0.7)1-8(14) cm, of sapling lvs (no further described) up to 18 cm, the petiole (1—)1.3—3.5(—4) cm, the longer interpinnal segments (often lacking in var. trapezifolia) 0.8-2.8(-3.5) cm; pinnae (when more than 1 pair) distally accrescent, the rachis of the furthest or penultimate pair longest, 2.5-9 cm, the longer interfoliolar segments 6—13 (— 14) or in var. trapezifolia 12—26(—31) mm; nectary between or close below first pinna-pair sessile or almost so, the stout stipe, if present, concealed by the head, this hemispherical-verruciform or low-convex but dimpled, in vertical view either round or obtusangulately scutiform (0.6-) 0.7-2.1 mm diam, in lateral view not over 0.6 mm tall, similar nectaries near random further pinna-pairs or these lacking, but much smaller, round or vertically elongate cupular ones close below 1-3 furthest pairs of lfts; minute paraphyllidia usually present, sometimes only at posterior side of pinna-pulvini; lft-pulvinules cross-wrinkled 0.6-1.4(-2) x 0.6-1.3 mm; lfts decrescent toward base of pinnae, thence either scarcely or greatly accrescent, in outline obtusely rhombic to rhombic-elliptic or -obovate from inequilaterally cuneate or subrectangular base, obtuse or emarginate, the terminal pair (1.3—) 1.6—6.5(—7) x 1- 3.6(-4.4) cm, (1.3-) 1.5-2.1 (-2.3) times as long as wide; the either straight diagonal or subcentric and gently incurved midrib giving rise on each side to ±5-9 major and sometimes as many and almost as strong intercalary secondary nerves brochidodrome within the at least incipiently revolute, always ciliolate margin, these sometimes generating a sinuous tertiary-reticulate venulation, the whole venation variable in strength and prominence, sometimes (especially in older lvs) almost immersed, sometimes sharply prominulous on both faces. Peduncles mostly solitary or geminate, seldom temate (l-)2.5-7.5(-10) cm; capitula or capituliform racemes ±(10—) 15— 45-fld, either compact or with one or more fls downwardly displaced on peduncle, the receptacle including very short terminal pedestal 2-11 mm; bracts linear-oblanceolate, oblanceolate or elliptic 0.7-1.6 mm, deciduous, or the lowest longer and more persistent; fls ordinarily dimorphic, terminal 1- (2-3) larger and coarser, with modified androecium, but these sometimes modified only as to androecium or abortive and early deciduous, or exceptionally wanting, the perianth of all fls 5-merous, densely brownish silky overall with appressed hairs; PERIPHERAL FLS: pedicel of proximal ones mostly 0.4-1.2 mm, rarely subobsolete, that of distal ones often a little shorter; calyx narrowly or widely turbinate-campanulate 1.7-3 x 1.4-2.1(2.4) mm, the low-deltate teeth 0.3-0.8(-0.9) mm; corolla 4—6.2(-7) mm, the ovate or lance-ovate lobes 1.6-2.8 x 1-1.5 mm; androecium (12-)14-25-merous, 15—23(—31) mm, the stemonozone 0.4—1.1 mm, the tube 2-4-(4.5) mm; ovary shortly stipitate, narrowly obovoid-ellipsoid, densely puberulent overall, rather abruptly contracted into the glabrous style but not truncate; style scarcely dilated at tip; TERMINAL FL(S): sessile, the calyx broadly campanulate (1.8-)2.2-3.4 x 2-2.6 mm, the corolla (5.5-)6.5-8.5 mm, the androecial tube 6-11 mm, either scarcely or well exserted, ±1-1.3 mm diam at separation of filaments, these either much or scarcely thickened proximally. Pods 1-2 per capitulum, sessile or almost so, in profile broad-linear decurved through ²/3-nearly 2 circles, when well fertilized 6-9.5 x 1-1.6 cm, 8-12-seeded (by random abortion of ovules often shorter), the leathery, fuscous or maroon-red, strigulose but glabrescent, nowhere pulpy valves framed by shallowly (at aborted ovules deeply) undulate ventral and evenly decurved dorsal sutures ±0.9-1.5 mm wide, low-convex over seeds, either distinctly or faintly venulose, internally orange and either smooth or minutely furfuraceous; dehiscence through the length of both sutures, the valves elastically coiling; seeds transverse, basifixed on ribbonlike funicle, plumply lentiform, in broad view as long as or a little longer than wide, 5-8 mm diam, the testa loosely investing the blue embryo, white and opaque near the hilum, thence translucent, pallid or lutescent in age, pleurogram 0.

In upland and non-inundated lowland, primary and secondary forest and forest-savanna ecotone, widespread over tropical South America from NW Colombia to NE Bolivia, W through Venezuela to Trinidad and Tobago and the Guianas, S in Amazonian Brazil to Rondônia and N Mato Grosso, disjunct in coastal forest of Bahia; Lesser Antilles southward from Guadeloupe; range and elevation more precisely stated under the varieties.

Abarema jupunba is distinguished ideally from close relatives by a syndrome of (a) leaflets finely, often only minutely, strigulose beneath, (b) convex and pored petiolar nectaries, (c) small, shortly pedicellate or subsessile, densely silky flowers, and (d) relatively thin-textured pod with valves uniformly cinnabar-red inside and white-and-blue seeds lacking pleurogram. It is exceptionally variable in leaf-formula and in size of leaflets, both between branches of one tree and between trees of different populations. The extreme leaf-forms were treated by Bentham (1875) as Pithecellobium micradenium and P. trapezifolium, but the numerous intermediates subsequently discovered and a low correlation between pinna number and either size or number of leaflets precludes recognition of more than one, no differences in either flower or fruit being apparent. Our concept of P. jupunba is the inclusive one developed by Urban and Britton & Rose. However, analysis of the copious material now accumulated shows that the macrophyllidious variants of the species occur only in the northeastern quarter of its whole range, in fact displacing the microphyllidious ones in all of Venezuela except its Amazonian corner and Maracaibo basin, and extending beyond Venezuela only into immediately adjoining countries and Dutch and French Guianas. It seems appropriate, therefore, to accept two varieties, even though, however they may be defined, there will inevitably be found some specimens ambiguously poised between them.

Because it comprises forms with larger and smaller leaflets and is one of the most widely dispersed members of its genus, A. jupunba is a conceptually useful prototype of the group of blue-seeded abaremas with rhombic or rhombic-obovate leaflets and apically conic ovary, and it provides a standard of comparison against which its more local relatives can be evaluated: in the macrophyllidious direction A. microcalyx, longipedunculata, villifera (probably, though pod is unknown), commutata, and adenophora’, in the microphyllidious one A. auriculata and polymorphic barbouriana. For diagnostic discussion see the accounts of those species.