Abarema villifera (Ducke) 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 villifera (Ducke) Barneby & J.W.Grimes

Type

"Habitat ad ripas inundabiles fluminis Curicuriary (Rio Negro affluentis) super cataractas, 26-2-1936 leg. A. Ducke, H[erb]. J[ard]. B[ot]. R[io de Janeiro] 35534." — Holotypus, RB!; isotypi, P!,U!,US!

Description

Species Description - Macrophyllidious trees 4-20 m, the new growth, except for lustrous glabrous upper face of strongly bicolored, at maturity subcoriaceous lfts, villosulous throughout with erect or curved, mostly golden- brown or sordid-whitish hairs to 0.4-0.7 mm, the capitula either solitary or paired in the axil of coevally expanding lvs, early immersed in foliage. Stipules linear or linear-lanceolate 2-3 x 0.3 mm, caducous. Lf-formula i-ii/2-3; lf-stks, including a scarcely differentiated pulvinus, 1-3 cm, the one interpinnal segment, when present, 7-23 mm, about as long as petiole; petiolar nectaries sessile or almost so, the first at or close below first pair of pinnae, plane or low-convex 1-2.4 mm diam, a similar one often near tip of lf-stk and yet smaller, shallow-concave ones on 1-2 furthest segments of pinna-rachis; pinnae when 2 pairs strongly accrescent, the rachis of the one or of the further one 25-45 mm, the longer interfoliolar segment 9-18 mm; subulate paraphyllidia at base of each pinna-rachis; lft-pulvinules 1-2.2 x 0.8-1 mm; lfts strongly accrescent distally, obliquely obovate-elliptic, or the proximal ones rhombic-ovate, from asymmetrically broad-cuneate or semicordate base, broadly rounded or shallowly emarginate, conspicuously revolute, the distal pair 28-70 x 13-36 mm, 1.4-2.1 times as long as wide; the gently incurved midrib little displaced, the secondary venation variable, described in key to variants. Peduncles 3-6 cm; capitula 9-15-fld, the receptacle including terminal pediment 2-3 mm; bracts linear or narrowly oblance-elliptic 1.2-3 x 0.3-0.6 mm, deciduous; fls dimorphic but all sessile or almost so, the white or greenish perianth of all 5-merous and densely subappressed-silky externally; PERIPHERAL FLS: calyx turbinate-campanulate 3-4.2 x 1.8-2.4 mm, the triangular teeth ±1 mm; corolla ±5-6.5 mm, the lanceolate lobes 1.8-2.3 mm; androecium 20-24-merous, 21-31 mm, the stemonozone <1 mm, the tube 1.7-3 mm; TERMINAL FL: usually solitary, sometimes paired, the calyx broadly campanulate 4—5.5 x 2.5-3 mm, the corolla 7-8 mm, the staminal tube 8-10 mm; ovary symmetrically ellipsoid, conical apically, densely silky-pubescent overall. Pods unknown.

Distribution and Ecology - In riparian forest subject to flooding, below 175 m, local on the upper forks of Río Negro in NW Amazonas, Brazil, and adjoining T. F. Amazonas, Venezuela, between 3°N and 1°20'S latitude; and (variant, see commentary below) in terra firme forest of lower Río Negro basin (Río Cueiras) in ±2°45'S. — Map 14. — Fl. II, IV, VII, the whole cycle unknown.

Discussion

Abarema villifera is readily recognized by few ample leaflets softly silky-villous beneath and by few-flowered capitula. In foliage it closely resembles the upland and allopatric A. commutata, which see for comment. As A. villifera is still unknown in fruit, it is not included in the cladistic analysis, and any relationship implied by its striking similarity to A. commutata remains unconfirmed.

On the upper Río Negro, the leaflets of A. villifera are pinnately veined, all minor venation being immersed in the epidermis. One collection from Río Cueiras, a tributary of the lower Río Negro shortly upstream from Manaus, differs strikingly in elaborately venulose leaflets and when better known will probably emerge as taxonomically distinct. The observed differences are as follows:

1.Venation of lfts simply pinnate, the secondary nerves from midrib 6-7 pairs, unbranched; upper Río Negro in SW Venezuela and adjacent Brazil variant a, typical

1.Venation of lfts reticulate, the secondary nerves from midrib 12 pairs or more, giving rise to a mesh of tertiary and quaternary venules prominulous on both faces; lower Rio Negro in central Amazonas, Brazil variant b

Distribution

Amazonas Brazil South America| Amazonas Venezuela South America|