Swartzia racemosa Benth.

Description

Type: Brazil, Pará: Caripi, on the beach, Aug 1849 (fl), R. Spruce 188 (Holotype: K).

Description: Tree, to ca. 30 m; trunk to 1.4 m in diameter, the bark exfoliating, scaly, the slash often with red-oxidizing exudate; pubescence of appressed, fairly straight whitish, grayish, or golden simple and malphigian hairs, becoming scurfy or matted with age, these mostly less than 0.2 mm long; young branchlets 1–4 mm thick, densely scurfy-strigulose, sometimes glabrescent. Leaves unifoliolate, with an articulation but not a proper axis apparent between the pulvinus and pulvinule; stipules 1.5–17 x 0.7–3.5 mm, triangular, lanceolate-elliptic, or oblanceolate, sometimes falcate, glabrous adaxially, thinly to densely scurfy-strigulose abaxially, glabrescent, conspicuously parallel-veined or the venation immersed, caducous; petioles wholly pulvinar, the pulvinus 2–5-5 mm, teterete to subterete, unwinged, often longitundianlly bicarinate adaxially, densely scurfy-strigulose, glabrescent; stipels highly reduced or relictual ca. 0.1–0.7 mm, triangular; petiolules 1.1 –3.5 mm, densely scurfy-strigulose, glabrescent; laminas 2 –3.3 x longer than wide, 5 –18 x 2 –7 cm, chartaceous, commonly elliptic to somewhat oblong, occasionally ovate or obovate, the margin usually deflexed, the base obtuse-rounded to broadly acute, the apex bluntly acuminate to caudo-acuminate, the acumen rounded or pointed, often briefly mucronate, ca. 0.5 –2 cm long, the adaxial surface glabrous or nearly so, sometimes sparsely strigulose on the midrib, the abaxial surface whitish- or grayish-canescent, minutely but fairly densely malphgio-strigulose, sometimes glabrescent, the venation inconspicuous, minutely prominulous to immersed adaxially, prominulous abaxially, the primary vein impressed adaxially, but sometimes cariniform within the furrow, raised abaxially, the secondary veins ca. 8 –12 on each side of primary vein, initially ascending at 20 –38°, curving upward distally and forming submarginal loops. Inflorescences simple or frequently compound racemes with a single order of branching, often 2-several fasciculate, borne from the axils of current leaves or from defoliate nodes of annotinous or slightly older branches; primary axes (0.6 –) 1 –7 cm long, 0.8 –1.7 mm thick near base, terete to somewhat compressed, thinly to densely scurfy-strigulose; bracts 2 –3.7 x 0.6 –1.6 mm, narrowly ovate- to triangular lanceolate, often flanked by a pair of stipules that are similar in apparence to the bracteoles, these often adnate to the bract and then forming a tridendate composite structure, essentially glabrous adaxially, but often with some pubescence at base, thinly to fairly densely scurfy-strigulose abaxially, often glabrescent toward apex, caducous; pedicels 2 –3.6 ( –6.4) mm long, 0.7 –1.4 mm thick at middle, dorso-ventrally compressed, often slightly constricted just above bracteoles, but then dialted apically, thinly to densely scurfy-strigulose; bracteoles 1.5 –2.8 x 0.3 –1 mm, oppsite to strongly subopposite, inserted from the base of the pedicel to near its apex, when strongly sub-opposite often with the basalmost one adnate to the inflorescence axis, narrowly triangular to ovate- or elliptic-lanceolate, glabrous adaxially, thinly to densely scurfy-strigulose abaxially, often glabrescent toward apex; flower buds 4 –5.4 x 3.8 –5 mm, ellipsoid to globose, weakly umbonate at apex, longitudinally venose-costate, mostly glabrous, but often thinly to fairly densely scufy-strigulose at base. Calyx mostly glabrous, but often thinly to fairly densely scurfy-strigulose at base abaxially; segments 3 –4 ( –5) in number, 3 –6 x 2.1 –5.9 mm, strongly recurved. Petal yellow (or possibly white); claw 2.5 –4 mm; blade broadly deltoid-ovate to oblate-elliptic, 4.7 –9 x 4.5 –7.5 mm, glabrous. Androecium glabrous, more or less zygomorphic, the stamens primarily of two sizes, but often with some intergradation; larger stamens 3 –9, abaxial, the filaments 5.6 –10.4 mm long, 0.2 –0.6 ( –0.8) mm thick near base, basally dilated, somewhat dorso-ventrally compressed, the anthers 0.9 –1.3 x 0.5 –0.9 mm, elliptic to oblong-elliptic in outline, apically invaginated between the thecae, the connetive not prolonged; smaller stamens 37 –95,, the filaments 2.4 –6.2 ( –7.4) x ca. 0.05 –0.1 ( –0.3) mm, the anthers 0.5 –1.1 x 0.5 –0.8 mm, elliptic in outline, apically invaginated between the thecae, the connetive not prolonged. Gynoecium monopistillate, glabrous; stipe 4 –6.3 x 0.3 –0.5 mm, terete to oval in cross-section; ovary 3.6 –5.9 x 1.3 –2 mm inequilaterally arcuate elliptic in outline, laterally compressed, glabrous, the locule glabrous; ovules 4 –8; style 0.5 –1.7 mm long, 0.3 –0.5 mm thick at middle, obliquely terminal, arcuate to recurved; stigma truncate to punctiform. Fruits green, glabrous; stipe 6.5 –9 mm long, ca. 1.4 –1.5 mm thick at middle, terete; body 2.9 –4.4 x 1.9 –2.5 cm, elliptic in outline, somewhat laterally compressed, broadly acute to obtuse or rounded at base, rounded and shortly apiculate at apex, often obliquely so. Seeds usually solitary, ca. 3.2 –3.5 x 1.5 –1.9 cm, elliptic-reniform in outline, laterally compressed; aril ca. 2.2 –2.5 x 1.4 –1.8 cm, elliptic, strongly convex over seed, the margin irregularly wavy but more or less entire, positioned more or less centrally on the hilar side of seed, covering a quarter to third of seed surface.

Common names: Pacapeuá (Portuguese?); geographical location: Amapá, Pará, Brazil; source: e.g., Ducke 605, Huber 1841, Maciel et al. 2125; Silva 5290. Parapeicá (Portuguese?): geographical location: Pará, Brazil; source: Ducke 15940. Caraipé-rana (Portuguese?): geographical location: Pará, Brazil; source: Spruce 188, 234. Multi duro (Portuguese): geographical location: Pará, Brazil; source: Pires 51785. Pitaica (Portuguese?): geographical location: Pará, Brazil; source: e.g., Cordeiro 4711, 4743.

Distribution: Swartzia racemosa occurs in the Brazilian states of Amapá and Pará along the lower coarse of the Amazon River, in its floodplain and along nearby tributaries, but apparently not much penetrating the interior uplands north and south of the Amazon. It also occurs on Marajó, Mexicana and Mosquiero Islands and undoubtedly on many other islands in the Amazon-Para River mouth. The eastern limit of distribution appears to be the Guamá basin east of Belém. The western limit of distribution is poorly documented, but north of the Amazon is at least as far as the lower Jari River, whereas south of the Amazon is perhaps the Pacajá-Caxiuna-Anapu drainage, east of the Xingu River mouth. An unnumbered collection made by Spruce in 1849 was reportedly taken somewhere along the Amazon River below Santarém, but the vagueness of the locality data, along with the fact that the species has not been re-collected anywhere near Santarém, make the record questionable.

Ecology: Swartzia racemosa appears to be associated with the extensive riverine forest of the lower Amazon, where it occurs in seasonally inundated varzea forest and on sand bar beaches; it may have a preference for sandy soils. The fact that these habitats are exposed to tidal influxes of blackish water suggests that the species is at least somewhat tolerant of high salinity. However, it occurs nearly as often in well-drained terra firme forest.

Phenology: Flowering and fruiting occur during any month of the year, but there is seemingly a peak in flowering from September to November.

Taxonomic notes: Within section Recurvae, S. racemosa belongs to a core group of species that possess malpighian trichomes and a glabrous gynoecium with the ovary relatively compact, not more than three times longer than wide. Torke and Schaal’s (2008) combined analysis of chloroplast and nuclear DNA sequences placed S. racemosa and S. recurva as sister taxa, albeit with weak support. Swartzia racemosa also appears to be very closely related to S. canescens and S. discocarpa, the latter not yet sampled in phylogenetic studies. But S. recurva differs from all three most obviously in having consistently unifoliolate leaves, with the primary vein strongly impressed on the upper surface. The gynoecium also has the stipe proportionately shorter than in any of its close relatives.

Uses: The species is said to yield good firewood (Anderson & Rosário 1452).

Etymology: The epithet refers to the racemose inflorescence of the species.

Conservation status: Swartzia racemosa has a fairly broad distribution, within which large areas of likely habitat persist, some of them nominally protected. It is not currently threatened.

Floras and Monographs

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

Map Distribution

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