Abarema piresii 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.

Family

Mimosaceae

Scientific Name

Abarema piresii Barneby & J.W.Grimes

Type

"Brazil, Fronteira Amazonas-Pará-Mato Grosso: Boca do rio Juruena, terra firme, 31.XII. 1951, J. Murça Pires 3704.’’-Holotypus, NY!; isotypus, IAN!.

Description

Species Description - Microphyllidious trees (5-)8-25 m with trunk 1.2-4 dm dbh, the young branches, lf-axes and peduncles densely puberulent with sordid or rusty, forwardly incurved hairs to 0.15-0.3 mm, the lfts bicolored, lustrous olivaceous above, paler dull beneath, except for often minutely puberulent midrib glabrous on both faces but minutely remotely ciliolate, the loosely few-fld capitula solitary or geminate in distal lf-axils, immersed in foliage. Stipules erect, linear-attenuate 2-5 x 0.4-0.5 mm, caducous from small white callus. Lf-formula (i-)ii—iii(—iv)/8-12(-13); lf-stks (0.5-)1.2-5.5 cm, the petiole including a scarcely differentiated pulvinus 3-10 mm, the longer interpinnal segments (0-)3-25 mm, the shallow ventral sulcus interrupted at each pair of pinnae by a globose, pyriform or fungiform, broadly obtuse or subtruncate nectary 0.6-1.4 x 0.6-2.5 mm, and smaller, stipitate or less often sessile nectaries at 4-8 further nodes of pinna-rachises; pinnae accrescent distally, the rachises of distal pair (3-)4-10.5 cm, the longer interfoliolar segments 5-9 mm; lft-pulvinules 0.5-0.8 x 0.5-0.9 mm; lfts decrescent proximally, thence (except for longer narrower furthest pair) subequilong, the opposite blades sessile against rachis, in outline obtusely rhombic from broadly cuneate base, those near and beyond midrachis 12-23 x 7-12 mm, 1.6-2.3 times as long as wide; the diagonal, nearly straight midrib giving rise to crowded secondary venules weakly brochidodrome just within the narrowly revolute margin, the whole venation bluntly prominulous above, more sharply so beneath. Peduncles (1.5—)2—5.5 cm; capitula ±12—22-fld, without androecia ±9-10 mm diam, the receptacle 3-5 mm; bracts herbaceous lanceolate 2-4.5 x 0.4-1 mm, 3-5-nerved, persistent at least through anthesis, often into fruiting; fls dimorphic, all sessile or almost so, the greenish perianth of all 5-merous, densely brown-puberulent on teeth or lobes but glabrescent proximally, the filaments white; PERIPHERAL FLS: calyx narrowly or turbinately campanulate, 3-3.5 mm, the obtuse teeth 0.8-1 mm; corolla cylindro-campanulate, 5-6 mm, the lanceolate lobes 1.7-2.5 x 0.8-1 mm; androecium 12-24-merous, 15-21 mm, the stemonozone ±1.5 mm, the tube 2-4 mm; ovary obliquely truncate at apex, glabrous; TERMINAL FL: calyx 2.7-4 x 2-2.5 mm; corolla 7-9.5 mm; staminal tube 9-10 mm. Pods 1-2 per capitulum, sessile or nearly so, persistent, in profile submoniliform, recurved or equivalently contorted through 1-1.5 circles, the dorsal suture evenly decurved, the ventral suture deeply impressed between seeds to form isthmi 1.5-4 mm wide, the (5—)8—14 biconvex 1-seeded segments 9-11 mm diam, as wide as or a little wider than long, framed by dorsally plane sutures, the ventral one 1.2-1.6 mm wide, the subligneous valves externally orange brunnescent, glabrous overall, densely coarsely sinuously venulose and reticulate, internally pale brown (not red), the endocarp adherent to mesocarp; dehiscence follicular, along the seminiferous suture only, the valves gaping to expose the seeds, these suspended on a crumpled but not dilated funicle, filling the cavity, when not quite ripe plumply discoid ±6.5 mm diam, the pale brown, translucent testa loosely investing the embryo, pleurogram 0.

Distribution and Ecology - In forest or at forest margin, on terra firme, preferring clayey or sandy clay soils, below 150 m, occasional in E Amazonian Brazil in lat. ±0-7°30/S, from E Amazonas downstream to Río Jarí in Pará, S to the lower Madeira and middle Tapajós rivers, at the mouth of Río Juruena perhaps entering extreme N Mato Grosso. — Map 11. — Fl. VI—IX.

Discussion

The leaves of A. piresii resemble those of the uncommon form of A. jupunba with relatively few (2-3) pairs of pinnae, but the moniliform fruit deeply indented from the ventral side into a series of one-seeded lobes, and dehiscent only through the gaping ventral suture, is diagnostic. The species was named in honor of the distinguished botanist João Murça Pires.

Common Names

angico branco

Distribution

Amazonas Brazil South America| Pará Brazil South America|