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Family:

Fabaceae (Magnoliophyta)

Accepted Name:

This name is currently accepted.

Description:

Type: Guyana, Essequibo River area, without date (bud), C. F. Appun 34 (holotype: K).

Description: Tree to 30 m; trunk muscular and dilated to narrowly buttressed at base in mature individuals, to 75 cm in diameter; bark flaky-exfoliating, gray-brown or reddish-brown; wood extremely dense, the sapwood cream-colored, the heartwood reddish-brown to dark purplish-brown; exudate red; young branchlets densely tawny-strigulose. Leaves imparipinnate, with (1–) 2–3 (–4) pairs of opposite to subopposite lateral leaflets, sometimes with the terminal leaflet abortive, often unifoliolate in saplings; stipules ca. 0.2–0.6 x 0.2–0.6 mm, triangular, strigulose abaxially, caducous, those of seedlings ca. 1–2 mm long, narrowly triangular to lanceolate; petiole 4.7–30 mm, unwinged, densely tawny-strigulose, sometimes glabrescent, the pulvinus 2–6 mm; rachis 1.2–14.5 cm, unwinged, longitudinally bicarinate adaxially, densely tawny-strigulose, sometimes glabrescent; stipels absent; petiolules 3.2–6.7 mm, densely tawny-strigulose, sometimes glabrescent; laminas 1.8–3.4 x longer than wide, 4.3–17.5 (–22.5) x 1.5–6.5 (–8) cm, chartaceous, mostly elliptic to oblong-elliptic, sometimes ovate or obovate, the margin often deflexed, the base acute to obtuse-rounded, the apex acuminate or caudo-acuminate, the acumen pointed to rounded, often briefly mucronate, 4–18 (–35) mm long, the adaxial surface glabrous, the abaxial surface densely golden- or tawny-strigulose, the trichomes minute, malpighian, the midrib depressed adaxially, raised abaxially, other venation raised-prominulous to immersed adaxially, rasied abaxially, the secondary veins 8–15, initially ascending at 18–33°, forming loose submarginal loops in distal half of leaflet, these with one to several included intersecondary veins semiparallel to secondaries but less ascending. Inflorescences simple racemes or compound racemes with 1–2 orders of branching, borne from axils of coeval leaves or from annotinous portion of branches, often 2–several-fasciculate, to ca. 30-flowered; axes (1.5–) 2.5–13 cm, densely golden- or tawny-strigulose; bracts 0.6–1.9 x 0.5–0.8 mm, triangular to ovate-lanceolate, strigulose abaxially; pedicels 4.6–11.5 mm, dorso-ventrally compressed, somewhat dilated apically, densely golden- or tawny-strigulose; bracteoles 0.5–0.8 mm, triangular to ovate-lanceolate; flower buds 3.6–5.8 x 3.5–5 mm, green, globose to ellipsoid, umbonate, mostly glabrous, strigulose at base. Calyx segments 3–4 in number, ca. 3.5–7 x 2.2–5 mm, green, subequal, more or less elliptic or oblong, strongly recurved, mostly glabrous, strigulose at base abaxially. Petal yellow or pale yellow, glabrous; claw 1.7–4.8 mm; limb 7.4–9.3 x 3.7–9.2 mm, ovate, elliptic or orbicular, the base acute to obtuse or truncate. Stamens glabrous, dimorphic, of two size classes; larger stamens 3–8 in number, adaxial, the filaments (5.1–) 6.8–11.8 mm, dorso-ventrally compressed basally, tapering apically, the anthers 1.1–1.5 x 0.7–1.1 mm, elliptic in outline; smaller stamens 49–86 in number, the filaments 3.2–8.6 mm, the anthers 0.5–1.1 x 0.4–1 mm, elliptic to rotund in outline. Gynoecium green to pale yellow, glabrous; stipe 6.8–10.2 mm; ovary 3.7–5.5 x 1.4–2 mm, inequilaterally arcuate-elliptic in outline, laterally compressed, the locule glabrous; ovules 4–10; style 0.5–2 mm, terminal arcuate, apically tapering; stigma punctiform. Fruits glaucous-green, glabrous; stipe 8.4–9.7 mm, linear-cylindrical; body 2.8–3.9 x 1.7–2.3 cm, elliptic-discoid in outline, laterally compressed, obtuse to rounded at base and apex, shortly apiculate by the persistent style. Seeds 1 per fruit, ca. 2.5–3 x 1.5 cm, oblong-ellipsoid, somewhat compressed laterally; aril ca. 2.1 x 1.1 cm, convex-elliptic covering about a quarter of seed on hilar side.

Common names: Wamara (Arawak); geographical location: Guyana; source: e.g., Appun 34, Davis D418 (Forest Department of British Guiana Record No. 2414), D419 (Record No. 2415), Fanshaw F51 (Record No. 2650), F1617 (Record No. 4353); Unikiakia (Arawak), geographical location: Guyana; source: Aitkin A27 (Forest Department of British Guyana Record No. 1065); Itiki couroballi (Arawak?), geographical location: Guyana; source: Imperial Institute 884; Brown ebony (Engish); geographical location: Guyana; source: Appun 34.

Geographic distribution: Swartzia leiocalycina occurs in central and northeastern Guyana and western Suriname. It has been found in the lower and middle basin of the Essequibo River, including the Cuyuni and Mazaruni drainages, in the Berbice drainage, and in the Kabalebo drainage.

Ecology: Swartzia leiocalycina is most prevalent in well-drained lowland forest on brown sandy soils of Pleistocene origin, where it is often co-dominant. It occurs less commonly on clay soils and white sand, sometimes near streams or rivers. Common associates include Aspidosperma excelsum, Chlorocardium rodiei, Eperua falcata, Eschweilera sagotiana and Mora gonggripii (Davis, 1941; ter Steege et al., 1993; ter Steege & Zondervan, 2000). The species has been reported to be nodulating (Perreijn, 2002).

Phenology: Flowering appears to peak from December to February, but has also been observed in July. Fruits are known from March.

Taxonomic notes: Swartzia leiocalycina possesses the characteristic features of S. section Recurvae, including malpighian trichomes, bracteolate pedicels, a yellow petal with the base of the limb acute to truncate, the gynoecium, with the stipe about twice as long as the ovary, which in turn is more than twice as long as the style, and the aril lacking macroscopic cellular divisions. In the phylogenetic study of Torke and Schaal (2008), S. leiocalycina was placed as the sister taxon of S. oblanceolata. It is also closely related to S. canescens and S. discocarpa. Among these and other species of section Recurvae with glabrous gynoecia, S. leiocalycina is readily distinguished by its densely golden or tawny-strigulose leaflet undersurface. This feature is shared with S. microcarpa, but that species has a densely strigulose (versus glabrous) ovary and distinctly alternate (versus opposite) leaflets.

Uses: Although its wood is extremely dense and difficult to work, and the sawdust potentially toxic, S. leiocalycina is a commercially important timber species. The rigidness of the wood, its high resistance to termites and rot and the attractive contrast between the beige outer-wood and purplish heartwood underlie a local and international market for the wood for a variety of specialty uses, including furniture, cabinets, paneling, wood flooring, tool handles, musical instruments, and decorative items. The heartwood is sometimes used as a substitute for ebony.

Etymology: The epithet combines the Greek prefix “leio” meaning “smooth” with the Latin for calyx and was given in reference to the essentially glabrous, smooth-surfaced calyx, which contrasts with the densely strigulose pedicels and inflorescence axes.

Conservation status: Although the documented geographical range of S. leiocalycina is quite limited and overharvesting may be a concern, the species in often abundant in its habitat and thus is probably not currently threatened. ter Steege et al. (2000) estimated that it is one of the most abundant tree species in the Guianas, based on extrapolation from plot inventories. The species is present in several protected areas, including the Iwokrama Rainforest Reserve.

Flora and Monograph Treatment(s):

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