Swartzia canescens Torke

Description

Authors: Benjamin M. Torke and Vidal de Freitas Mansano

Type: French Guiana. Distr. Cayenne: Rivie`re Camopi, between Saut Petit Impossible and Saut Grand Impossible, 10 Feb1968 (fl), R. A. A. Oldeman & C. Sastre 167 (holotype: CAY; isotypes: COL, NY, US).

Description: Tree to ca. 30 m; trunk angular, sometimes buttressed; bark smooth or scaly; young branchlets glabrous to densely minute-strigulose. Leaves imparipinnate, with (1-) 2-3 pairs of opposite to subopposite lateral leaflets, occasionally with the terminal leaflet abortive; stipules narrowly triangular to lanceolate, (0.6-) 1-2.5 (-4) x 0.3-0.6 (-1) mm, minute-strigulose abaxially, sometimes glabrescent, caducous; petioles often longitudinally bi-ridged or distally marginate above, 8-24 mm, moderately to fairly densely minute-strigulose, pulvinus 1.7-4.6 (-6.4) mm; rachis longitudinally bi-ridged to marginate above, sometimes narrowly winged, (1.5-) 3-7 (-12) cm, fairly densely minute strigulose, sometimes glabrescent; stipels triangular to lanceolate, ca. 0.2-0.7 (-2.9) mm, often caducous; petiolules 1.7-4.6 mm, fairly densely minute-strigulose, sometimes glabrescent; leaflet blades chartaceous, elliptic to somewhat obovate, 1.7-3.3 x as long as wide, 4-12 (-18.5) x 1.5-4.8 (-7.5) cm, base usually acute, sometimes obtuse or rounded, apex acuminate, acumen rounded or weakly retuse, 3-12 mm, upper surface glabrous, lower surface typically whitish- or grayish-canescent from the fairly dense minutely malphigio-strigulose pubescence, the trichome bases persistent, midrib raised on both leaflet surfaces, higher order venation raised-prominulous to immersed, secondary veins ca. 7--12 on each side of midrib, initially fairly straight, ascending at 16-37°, curving distally and forming loose submarginal loops, with included intersecondary and tertiary veins more or less parallel to secondaries. Inflorescences simple or compound racemes with a single order of branching, borne in leaf axils or on defoliate portion of branchlets just below leaves, sometimes 2-several-fascicled, to ca. 30-flowered; axes fairly densely golden or ferruginous minute-strigulose, primary ones 2.5-11 cm; bracts triangular to ovate-lanceolate, 0.8-2.1 x 0.5-1 mm, sometimes supplied with a pair of stipules similar to those of the foliage leaves, glabrous adaxially, densely strigulose abaxially; pedicels dorso-ventrally compressed, distally dilated, 4-9 mm, densely golden or ferruginous minute-strigulose; bracteoles opposite to subopposite, usually inserted in distal half of pedicel, triangular to narrowly lanceolate, 0.6-2 mm, densely strigulose abaxially; flower buds globose, usually umbonate, 4.6-5.6 x 4.2-5.3 mm, thinly to fairly densely golden or ferruginous strigulose. Calyx green, glabrous within, strigulose without; segments 4-5, subequal, recurved, ca. 4-6 x 1.5-5 mm. Petal white, glabrous; claw 2.8-3.3 mm; blade rotund, the base more or less truncate, 6.7-8.3 x 5.5-8.4 mm. Androecium glabrous, the stamens dimorphic, arranged in two groups; stamens of the abaxial group 4-7, filaments white, 7.6-11.5 mm, anthers elliptic in outline, 1.2-1.5 x 0.8-0.9 mm; stamens of the adaxial group ca. 60, filaments white, 4.5-8 mm, anthers elliptic in outline, 1-1.4 x 0.7-0.9 mm. Gynoecium glabrous; stipe 4.7-6.4 mm; ovary inequilaterally arcuate-elliptic in outline, laterally compressed, 5.1-5.3 x 1.5-1.7 mm, locule glabrous, ovules ca. 10; style oblique to lateral at ovary apex, recurved, 1-1.2 mm; stigma punctiform. Fruits glabrous; stipe 6-8 mm; body rounded-ellipsoid to slightly obovoid, usually apiculate at apex by persistent style, 1.8-3.2 x 1.2-1.8 cm. Seeds 1-2, more or less ellipsoid, ca. 1.9 x 1.2 cm; aril white, inequilaterally hood-shaped, ca. 1.3 cm long, enclosing basal two-thirds of seed.

Common names: Gomeira branca (Portuguese); geographic location: Brazil; sources: N. A. Rosa 1222, 1223. Mututi duro (Portuguese); geographic location: Brazil; sources: M. J. Pires & N. T. Silva 2140, N. A. Rosa 1334. Pacapeuá (?); geographic location: Brazil; sources: M. J. Pires & N. T. Silva 1988, 1993. Watalãwã (?); geographic location: French Guiana; source: P. Grenand 569.

Geographic distribution: At less than 800 m in interior parts of French Guiana, southeastern Suriname, and northeastern Brazil, in the states of Amapá and northeastern Pará. In Brazil, the species is probably widely distributed in the poorly collected Serra Tumucumaque and the river basins that drain it. It has been collected in the vicinity of Monte Dourado in the basin of the Rio Jari but is not known to occur south of the Amazon River, nor does it appear to occur in the relatively well sampled Trombetas basin in northwestern Pará, where it is replaced by related species.

Ecology: Swartzia canescens occurs in well drained "terra firme" rainforest, frequently in hilly or mountainous terrain, sometimes near streams or rivers. Nothing has been recorded of its pollination or dispersal ecology.

Phenology: Flowers are known from December through March, mature fruits from late March through May.

Taxonomic notes: Swartzia canescens belongs to Swartzia section Recurvae, within which it is perhaps most closely related to Swartzia discocarpa, a poorly known species found in the Tapajós basin and adjacent drainages south of the Amazon River. It differs from S. discocarpa in its pubescent (versus glabrous) flower buds, white (versus yellow) petal, more elongate ovary, and ellipsoid (versus discoid) fruits.

Etymology: The specific epithet refers to the typically whitish or grayish aspect of the lower leaflet surface.

Conservation status: Given its fairly wide geographic range in the interior of northeastern Amazonia, which is still dominated by intact Amazonian wilderness, S. canescens is probably not currently threatened. The fact that this distinctive species was not formally described until 2007 is a testament to the remoteness of much of its likely geographical range. Swartzia canescens has been documented in several protected areas, including the massive Parque Nacional Montanhas do Tumucumaque in Brazil.

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