Oxandra riedeliana R.E.Fr.

Junikka, L., Maas, P. J. M., Maas-van de Kamer, H. & Westra, L. Y. Th., 2016, Revision of Oxandra (Annonaceae), Blumea 61 (3), pp. 215-266 : 251

20. Oxandra riedeliana R.E.Fr. — Fig. 20, 21a, b; Map 10

Oxandra riedeliana R.E.Fr. (1906) 2, f. 7–9. — Type: Riedel 1389 (holo S; iso K, M, MPU), Brazil, Amazonas, Borba, Aug. 1828.

Tree 3–30 m tall, 10–28 cm diam; young twigs glabrous. Leaves: petiole 2–5 mm long, 1–2 mm diam; lamina narrowly rhombic, narrowly ovate or narrowly obovate, 6–17 by 2–6 cm (leaf index 2.5–3.1), chartaceous, not verruculose, shiny and greyish green to greyish brown above, brownish below, glabrous above and below, base acute to attenuate, apex acuminate (acumen 5–15 mm long) to acute, primary vein raised above, secondary veins distinct, 7–12 on either side of primary vein, raised above, angle of secondary veins with primary vein 45–80°, smallest distance between loops and margin 2–3 mm, tertiary veins slightly raised above, reticulate. Flowers in 1–12-flowered inflorescences; pedicels 2–6 mm long, 0.5–1 mm diam, fruiting pedicels 5–7 mm long, 1–1.5 mm diam, rather densely to sparsely covered with appressed hairs; bracts 5–6, depressed ovate, 0.5–1 mm long, outer side sparsely covered with appressed hairs; flower buds globose; sepals shallowly to broadly ovate-triangular, 1–1.5 by 1–2 mm, outer side sparsely covered with appressed hairs to glabrous; petals white to yellow in vivo, elliptic to obovate, 6–7 by 2–5 mm, outer side glabrous; stamens 11–18, 2–3 mm long, apex of connective narrowly triangular to narrowly ovate; carpels ≤ 7. Monocarps 1–6, green, maturing dark red in vivo, black in sicco, globose to broadly ellipsoid, 12–18 by 11–16 mm, glabrous, apex rounded, wall 0.5–3 mm thick, stipes 1–2 by 1–2 mm. Seed globose or ellipsoid, 9–12 by 8–11 mm, pale brown to cream, surface transversely striate, ruminations spiniform.

Distribution — Colombia (Amazonas, Vaupés), Brazil (Acre, Amazonas, Pará, Rondônia, Roraima), Ecuador (Napo, Orellana, Pastaza), Peru (Cusco, Loreto, Madre de Dios), Bolivia (Santa Cruz).

Habitat & Ecology — In non-inundated or often periodically inundated (igapó, tahuampa, várzea) forest or open swamp forest, on sandy to clayey soil. At elevations of 0– 700 m. Flowering: Mainly between July and December; fruiting: October to June.

Vernacular names — Bolivia: Singa colorada (P.F. Foster et al. 357, 439). Brazil: Envira (Gottsberger & DÖring 14-19186, Luize 270, 296, M. Silva 753), Envira-de-tambaquí (D. Coêlho et al. INPA 81953, Souza et al. 156, 157), Envira-de-várzea ( Pardo et al. 54), Envira-preta-desconhecida ( Rosa et al. 5325), Envira-preta-folha-media ( Rosa et al. 5661), Envira-surucucu ( Barbieri 24), Envireira-branca ( Souza 150), Juvueira-algodão (Capucho 448). Ecuador: Pantomo (Huaorani name, Freire & Naranjo 709, Naranjo & Freire 371).

Uses — Envira usada para amaração em geral e a madeira para lenha ( Silveira et al. 985, Brazil).

Field observations — Fruit edible (Freire & Naranjo 709, Naranjo & Freire 371, Ecuador).

Note — Oxandra riedeliana shares with O. polyantha a many-flowered inflorescence. For the differences between both species see under O. polyantha .