Eperua leucantha Benth.

Eperua leucantha Bentham

Eperua leucantha Bentham, Fl. Bras. 15(2):225, 1870.

Small to large tree (8−)12–25 m tall, (10−)50–60 cm in diameter, the bark gray, smooth, the branchlets micropuberulous at first, glabrescent; stipules deciduous, lanceolate, sometimes somewhat arcuate, joined in an intrapetiolar body 3–5 mm long, 1.5–2 mm wide, glabrous except marginally ciliolate; petioles (17−)25–40 (−55) mm long, glabrous or infrequently micropuberulous and glabrescent, the rachis (27−)50–95 (−123) mm long, glabrous or pubescent as petioles; leaflets mostly 3-jugate, sometimes 2- or infrequently 4-jugate, the petiolules (5−)7–8 (−10) mm long, usually glabrous but sometimes micropuberulous, sulcate on upper surface, the blades pellucid-punctate, (8−)10–16 (−20) cm long, 3.5–7 (−8.5) cm wide, chartaceous to thinly coriaceous, plane, falcate-elliptic, the base mostly rounded-obtuse or obtuse, sometimes the upper pairs acute basally, infrequently the lower side of the leaflet obtuse and the upper side attenuate-acute, the apex acuminate to long-acuminate, the tip often obtuse and usually mucronate, glabrous or rarely micropuberulous at the base of the costa on the upper surface, the venation prominulous to subobscure; inflorescence a terminal, pendent raceme of racemes (37−)60–90 (−116) cm long, the main axis micropuberulous, the axis of the lateral racemes (6−)7–8 (−10) mm long, microstrigulose, the bracts caducous, the bracteoles arising about midway on the pedicels, caducous; pedicels (5−) 10–14 (−22) mm long, micropuberulous to microstrigulose, the hairlets grayish, arcuate, the hypanthium (3−)4–5.5 mm long, 5–7 mm in diameter, microstrigulose externally, the nectaries slightly exserted, inconspicuous; sepals pellucid-punctate, concave, fleshy, white, oval to oblong, obtuse, two outer ones broader and cucullate, (15−) 18–20 (−29) mm long, 7–10 (−12) mm wide, micropuberulous or microstrigulose externally, inner surfaces glabrous; petal white, 20–33 mm long, 36–55 mm wide, broadly flabelliform, basally truncate, sessile, glabrous, four petalodia 0.8–1.5 (−5) mm long, 0.8–1.5 mm wide, mostly semicircular to oblate or oval; all 10 stamens apparently fertile, filaments joined at the base in a subequilateral tube 3.5 to 5 mm long, the tube and the base of shorter filaments sericeous externally and on the inner surfaces, the longer stamens 3856 mm long, the shorter ones 30–43 mm long, the anthers 5–8 mm long, 2–3 mm wide, oval to oblong, the thecae microtessellate; stigma capitate, sometimes somewhat bilobed, the style 33–53 mm long, glabrous, the ovary sericeous-velutinous, 6–10 mm long, 3–4 mm wide, oblong-oblanceolate or oblong-obovate, the gynophore sericeous, 2–5 mm long; fruit 25–31 cm long, 6.5–9.5 cm wide, minutely strigulose, seeds oval, flat, 35 mm long and 21 mm wide.

TYPE COLLECTION.—R. Spruce 2021 (holotype K, isotypes BM, G, GH, M, P, W), “Rio Negro, moist forest at Uanauaca, Jan 52,” Amazonas, Brazil.

On the holotype label, Spruce records the following:

This tree, called Jauacaná in Lingoa Geral grows throughout the Upper R ío Negro, Uaupés and Casiquiare, where along with the Jebarú [Eperua purpurea] it is characteristic of the caatingas, and is perhaps the more frequent of the two. It flowers nearly throughout the dry season, but is in greatest perfection in the months of September & October. No use seems to be made of any part of it, but the flowers afford a great deal of honey to bees, as do also those of two species of Humirium growing in the driest parts of the caatingas & flowering at the same time. When the Indians see these trees flowering copiously they predict an abundance of wild honey.

DISTRIBUTION.—Frequent in uppermost Rio Negro Basin in Brazil, west to the Río Vaupes drainage of southeastern Colombia, east and north to the Río Guainia-Río Casiquiare in southwestern Venezuela on sandy soils sometimes in savanna-border forest, at 120 to 250 m elevation; flowering October to January; fruiting February to April.

COLOMBIA. Vaupés: San Felipe, Río Negro, 13–25 Nov 1952, Humbert 27386 bis (US); Río Kuduyari, 16 Oct 1952, Schultes & Cabrera 17872 (BM, GH, NY, U, US). VENEZUELA. Amazonas: Yavita-Pimichin Trail, near Pimichin, 21 Nov 1953, Maguire et al 36307 (NY, US); Río Yatua near Caño Tauavaca, 4 Dec 1953, Maguire et al 36508 (F, NY); Río Yatua near Cerro de la Neblina, 3 Jan 1958, Maguire et al 42610 (F, GH, NY, RB, U, US); San Carlos de Rio Negro, 17–18 Apr 1970, Steyermark & Bunting 102733 (US); Yavita, 23 Jan 1942, Ll. Williams 13939 (A, G, RB, US); Maroa, Río Guainia, 17 Feb 1942, Ll. Williams 14390 (F, G, US); Pimichin, Río Guainia, 3 Apr 1942, Ll. Williams 14940 (G), 1 Apr 1942, 14942 (F, US); Capihuara, alto Casiquiare, 5 June 1942, Ll. Williams 15801 (F, G, US). BRAZIL. Amazonas: São Gabriel, Rio Negro, 29 Oct 1932, Ducke 164 (A, F. NY); Rio Negro above mouth of Rio Curicuriary, 19 Nov 1929, Ducke 23289 (G, RB, US); São Gabriel, upper Rio Negro, 28 Oct 1932, Ducke 23732 (P, RB, U); Porto Curucuhy, Rio Negro, 6 Oct 1945, Froes 21104 (F, IAN, NY, US); São Felipe, Rio Negro, 1 Oct 1952, Froes 28826 (IAN); Rio Cauaburi, 7 Nov 1965, Maguire et al 60130 (F, NY, US); Marabitanas, 20 Apr 1947, Pires 481 (IAN); Rio Negro-Rio Vaupés, 1 May 1947, Pires 531 (NY, US); Rio Vaupés, Taraquá, Pires 978 (IAN); road from Camanaus to Vaupés, 30 Oct 1971, Prance et al 15684 (GH, M, NY, U, US); Rio Negro, Ilha das Flõres, 8 March 1959, Rodrigues & Pires 178 (IAN, US); upper Rio Negro, Ilha das Flores, 17 Feb 1959, Rodrigues 905 (U, US).

LOCAL NAMES AND USES.—Acanã, Iuacanã (Rodrigues 905), jauacanã (Spruce 2021), yaguana, yahuana (Ll. Williams 14390), yauacano (Ducke 23732). The wood is very heavy and is used locally in Venezuela for house posts and for bridges.

Some of the stamens (two to six) in flowers of E. leucantha do not bear fertile anthers, a characteristic shared with E. falcata. The white petal of E. leucantha contrasts sharply with all the other species with the elongate, pendent inflorescences, although less so with E. glabra which has a cream-colored petal. The nearest relative is unquestionably E. venosa which has a deep rose-colored petal with the base attenuate and puberulous externally, and ten fertile stamens. Their pollens are virtually identical (cf. discussion following E. venosa).