Tetrameranthus R.E.Fr.

Westra, Lubbert Y. T. & Maas, Paul J. M., 2012, Tetrameranthus (Annonaceae) revisited including a new species, PhytoKeys 12, pp. 1-21 : 3-4

Genus Tetrameranthus R.E.Fr.

Tetrameranthus Acta Horti Bergiani 12(3): 554. fig. 41. 1939; Westra, Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen, ser. C.88: 449-482. 1985.

Type.

Tetrameranthus duckei R.E.Fr.

Description.

Trees or shrubs. Leafy twigs and most floral parts sparsely to densely covered with stellate to simple hairs to glabrous. Leaves spirally arranged, often concen trated towards the end of the branches, primary vein impressed to slightly raised on the upper side. Inflorescences axillary, 1-flowered to several-flowered and umbel-like, bracts up to 4 below the articulation. Flowers bisexual, 4-merous or less often 5-6-merous, white to yellow or cream; sepals 4(-6), imbricate, free or basally connate; petals 8(-12), free, subequal, imbricate, much longer than the sepals, often with a callus at the inner base; stamens numerous, connective shield discoid, either flat, cushion-shaped, or with a conical prolongation; carpels c. 5-30, ovules 1-2(-3), lateral, stigma sessile, more or less lobed. Fruit apocarpous; monocarps 1-15, free, sessile or sometimes narrowed into a short and thick stipe-like base, indehiscent, sometimes constricted, wall rather thick (1-7 mm) and fleshy. Seeds 1-2(-3) per monocarp, lower one near the base, upper one(s) lateral.

Distribution.

Seven species in the Amazon regions of Venezuela, Colombia, Brazil, Peru, and Ecuador, but also in the Colombian state of Chocó and in French Guiana and neighboring Amapá, Brazil.

Key to the species of Tetrameranthus

la	Young plant parts covered with stellate hairs ≤0.2 mm long; primary vein mostly flat (or slightly raised or slightly impressed) above	2
1b	Young plant parts covered with stellate and simple hairs ≥0.5 mm long; primary vein impressed (exceptionally almost flat) above	3
2a	Inflorescences with up to 5 umbellately arranged flowers; peduncle manifest, ≥5 mm long (Amazonian Peru and Brazil)	Tetrameranthus umbellatus
2b	Inflorescences 1-flowered; peduncle inconspicuous, <1 mm long. (Amazonian Peru and Brazil and the Colombian states of Amazonas and Chocó)	Tetrameranthus laomae
3a	Monocarps globose or almost; perianth (as far as known) of 6-merous whorls (Amazonian Ecuador)	Tetrameranthus globuliferus
3b	Monocarps ellipsoid, oblongoid or fusiform; perianth of 4-merous or less often 5-merous whorls	4
4a	Monocarps, both 1- and more-seeded ones, ellipsoid or fusiform, without constriction or with a weak constriction	5
4b	2-Seeded monocarps oblongoid, with a manifest oblique constriction about the middle	6
5a	Monocarps 7-15, 35-60 by 20-30 mm, wall shriveled in sicco; petioles ≤10 mm long (French Guiana and the Brazilian state of Amapá)	Tetrameranthus guianensis
5b	Monocarps 1-3, to c. 70 by 40 mm, wall not shriveled in sicco; petioles ≥20 mm long (Amazonian Peru, vicinity of Iquitos)	Tetrameranthus pachycarpus
6a	Monocarps ≥35 mm in diam.; tall tree (Amazonian Colombia)	Tetrameranthus macrocarpus
6b	Monocarps ≤25 mm in diam.; shrub or small tree ≤12 m (Amazonian Colombia, Venezuela, and Brazil)	Tetrameranthus duckei