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Family:

Fabaceae (Magnoliophyta)

Accepted Name:

This name is currently accepted.

Description:

Type: Guyana, [Amazonas]: Cuyuni River, above Matopi Falls, 6 Mar 1931 (fl), J. B. Aitken A52 (Forest Department of British Guiana Record No. 1090) (Holotype: K).

Description: Tree to 30 m, occasionally fertile when only 1.5 m tall; trunk circular, buttressed in large individuals, occasionally to 40 cm in diameter above buttresses, the outer bark dark gray-brown, smooth to finely fissured or rugose-tuberculate, the inner bark yellowish-cream, exterior to a blackish cob-webby reticulum, the sap wood bearing red-oxidizing watery exudate; pubescence of appressed, fairly straight whitish or fulvous, simple or malpighian trichomes, these mostly less than 0.2 mm long; leaf-bearing branchlets 1.5–4 mm thick at middle of internodes, glabrous to thinly strigulose, more densely so on new growth, glabrescent. Leaves imparipinnate, with (1–) 2 (–4) opposite (to subopposite) lateral leaflets, sometimes with the terminal leaflet abortive; stipules 1–22 x 0.4–9.4 mm, triangular or elliptic to falcate-lanceolate, entirely glabrous or with a few appressed hairs abaxially, parallel-veined, conspicuously venulose or the venation immersed, often caducous; petiole 0.5–4.2 cm long, 0.9–2.3 mm thick at center, often marginate or winged beyond the pulvinus, glabrous to sparsely strigulose, the pulvinus 2.5–9 x 1.2–3.3 mm; rachis 0.6–9 cm long, with the segements usually distinctly winged, glabrous to sparsely strigulose, the wings 1.5–8.5 (–11) mm wide measured across rachis, chartaceous, venulose, obtriangular to oblong, bidentate and stipellate or more or less truncate at apex, glabrous to sparsely strigulose, the stipels ca. 0.2–1.5 mm long, triangular, poorly differentiated from rachis wings, frequently caducous; petiolules 1.5–4.9 x 1–2.7 mm, glabrous to sparsely minute-strigulose; leaflet blades 1.6–3.3 x as long as wide, (3–) 5–22 x (1.2–) 2–7.5 cm, chartaceous, elliptic or obovate, the margin decurved, the base acute or obtuse, the apex acuminate, acute, or obtuse, the acumen, when present rounded or pointed, sometimes briefly mucronate, ca. 2–12 mm long, the adaxial surface glabrous, the abaxial surface usually whitish- or grayish-glaucous, thinly and minitely strigulose, often glabrescent, the venation prominulous on both surfaces, the midrib raised-cariniform adaxially, the ca. 9-14 major secondary veins initially ascending at 17–35°, loosely brochidodromous submarginally, the minor secondary and tertiary veins fairly straight and more or less parallel to the major secondaries, higher order venation reticulate adaxially, reticulate to immersed abaxially. Inflorescences simple racemes or loosly branched compound racemes with a single order of branching, borne from leaf axils or from defoliote nodes of year-old or somewhat older branchlets, occasionally pseudo-terminal, sometimes two-several fasciculate, to ca. 30-flowered; axes 2–19.5 cm long, 1–3 mm thick near base, terete or angular in cross section; bracts 1.4–3.4 x 0.7–1.2 mm, triangular or ovate to ovate-lanceolate, glabrous adaxially, thinly to somewhat densely strigulose abaxially, sometimes glabrescent; pedicels 6.7–13 mm long, 0.9–1.9 mm thick at middle, dorso-ventrally compressed, often somewhat constricted above bracteoles, thinly strigulose, glabrescent toward apex; bracteoles 0.9–3.1 x 0.4–0.7 mm, opposite to strongly subopposite, inserted in the distal two-thirds of pedicel, triangular or ovate to ovate-lanceolate or oblong-lanceolate, thinly to somewhat densely stigulose abaxially, sometimes glabrescent; flower buds 7.1–10.1 x 5.2–7.3 mm, ellipsoid or ovoid, the apex usually broadly acute, costate-venulose, glabrous or essentially so. Calyx glabrous segments 3–5 in number, 2.7–8.8 mm wide, strongly recurved. Corolla monopetalous; petal yellow, the claw, 2.9–6.3 mm long, 0.6–1.8 mm wide at middle, the limb ellptic to orbicular or broadly ovate, the base obtuse to truncate, 9.4–13.8 x 9.4–14.6 mm, glabrous. Androecium glabrous, more or less zygomorhic, the stamens of two sizes; larger stamens 6–9, the filaments 8.4–19 mm long, 0.3–0.9 mm thick near base, basally dilated, dorso-ventrally compressed, the anthers 1.6–1.8 x 0.8–1.3 mm, elliptic or oblong-elliptic in outline, the connective not prolonged beyond thecae; smaller stamens 89–171, the filaments 4.6–13.3 mm long, 0.1–0.4 mm thick near base, the anthers 0.8–1.7 x 0.6–1 mm, elliptic or orbicular to oblong-elliptic in outline, the connective not prolonged beyond thecae. Gynoecium monopistillate, glsbrous; stipe 5.7–13 mm long, 0.5–0.8 mm thick at middle, round or oval in cross section; ovary 4.7–9 x 2.1–2.8 mm, inequilaterally obovate to oblong-lunate, laterally compressed, the locule glabrous; ovules 7–11; style 0.8–3.3 mm long, 0.4–0.7 mm thick at middle, obliquely terminal, recurved; stigma truncate to punctiform. Fruits green, glabrous; stipe 1.1–1.8 cm long, 1.5–2.3 mm thick at middle, terete body 2.7–4 x 1.6–2.4 cm, ellipsoid, apiculate by the persistent style, the wall 0.7–2.1 mm thick. Seeds usually 1 per fruit, ca. 2.4–3.3 x 1–1.5 cm, ellipsoid, somewhat compressed laterally; aril ca. 2–2.4 x 1.1–1.8 cm, white or yellowish, convex-elliptic, erose-margined, positioned centrally on hilar side of seed, covering a quarter to a third of seed surface.

Common names: Serebedan (Language?); geographical location: Guyana; source: e.g., Davis D566, Fanshawe F381, F597. Seribidani (Language?); geographical location: Guyana; source: Hohenkirk 8899. Paarse ÿzerhart (Language?); geographical location: Suriname; source: Jimenez-Saa 1600. Gombeira da folha miuda (Portuguese); geographical location: Pará, Brazil; source: Faria et al. SMF 1189. Melancieira (Portuguese); geographical location: Amazonas, Brazil; source: Vicentini & Silva 472. Ucabú (Portuguese); geographical location: Pará, Brazil; source: Oliveira 1908.

Geographic distribution: The documented range of S. oblanceolata is split between northern and southern areas of distribution. In the north it occurs, apparently somewhat patchily, throughout much of Guyana, Suriname and French Guiana, from the Cuyuni, Mazaruni, and Essequibo drainages in Guyana to the Oyapock drainage in French Guiana southward to the Sipaliwini Savanna in southern Suriname and northern Pará, Brazil. The southern area of distribution lies in east-central Amazonian Brazil, on both sides of the Amazon River. South of the River, it has been found in the lower reaches of the Tapajos and nearby drainages. North of the River, it is known from the lower Trombetas drainage and the vicinity of Manaus. The apparent disjunction between Guianan and Amazonian areas of distribution may be real, but much of the intervening area is severely under-sampled. Collections have been gathered from near sea level to about 600 m elevation.

Ecology: Swartzia oblanceolata occurs primarily in upland terra firme forest, sometimes along rivers, but apparently not in regularly inundated forest. In the Guianas, it displays a preference for sandy soils, particularly white sands, and may be associated with forest dominated by Eperua falcata, Dimorphandra conjugata, or Ocotea rodiaei. But it also occurs in forests on clay-dominated substrates and is found mainly in the latter in the southern Amazonian area of distribution. In the Nassau Mountains in Suriname, the species has been collected near exposed bauxite.

Phenology: Peak flowering appears to be from January to April, but flowering has also been observed in June, July and November. Fruiting apparently occurs mainly from February to June, but has been recorded in October and November.

Taxonomic notes: In a phylogenetic analysis of combined chloroplast and nuclear DNA sequences (Torke & Schaal 2008), S. oblanceolata was placed as the sister taxon of S. leiocalycina, which together formed a clade placed sister to another containing S. canescens, S. racemosa, and S. recurva. In the context of section Recurvae, these species and several others not yet sampled in phylogenetic studies, such as S. discocarpa and S. vaupesiana, are united by the possession of malpighian trichomes and glabrous gynoecia with the ovary less than 3 times longer than wide. Features that are useful for distinguishing S. oblanceolata from these and other species of the section include a winged leaf rachis, glabrous flower buds, a glabrous calyx, and relatively large stipules. Other distinctive characters include the often whitish- or grayish-glaucous leaflet undersurface, the typically dark gray-brown bark, and a blackish reticulum in the inner bark that is usually apparent in the trunk slash. Swartzia oblanceolata displays nontrivial variation in the size and shape of morphological structures, and in some cases in the number of serially repeated structures such as stamens. When viewed across the available material, these differences are continuous or at least the discrepancies are not so large as to be unlikely to be bridged by additional sampling; very few flowering specimens have been made from the Brazilian populations.

Uses: No uses have been recorded.

Etymology: The epithet presumably refers to the frequently oblanceolate leaflets.

Conservation status: The species is not currently threatened. The geographical distribution of S. oblanceolata is quite large. The species has been found in several protected areas and likely occurs in many others. The relative paucity of specimens probably reflects patchy abundance and a preference for sandy substrates.

Flora and Monograph Treatment(s):

Swartzia oblanceolata Sandwith: [Article] Cowan, Richard S. 1967. Swartzia (Leguminosae, Caesalpinioideae Swartzieae). Fl. Neotrop. Monogr. 1: 3-228.