Vanilla decaryana H.Perrier, Bull. Mus. Natl. Hist. Nat., II, 6: 194 (1934).
Plants very branched, aphyllous, stems of a greenish-brown, thick, glabrous, to 2-4 m long, climbing on the trunks, flat or pendent at the tops of trees. Clusters 20-40 flowered; bracts thick, generally equaling half the length of the pedicel; fiowers with the sepals greenish and the labellum white. Sepals obtuse, sub apiculate apically, shortly joined by their base to the petals and labellum, the median obovate-oblong (25 x 8 mm) attenuate in the superior third from the base and 15 veined, the laterals slightly narrower and slightly curved. Petals slightly larger than the sepals (30 x 8 mm) thinner, median vein projecting behind, the veins (generally) straight or slightly undulate. Labellum 3-3.5 cm long, joined basally to the column for l cm, dilate above in an obrhomboidal lamina, to 2 cm wide in the apical quarter, triangular-apiculate apically; provided basally with 2 rnedian keels, parallel, covered with hairs, irregular, thick, densely mossy. separated by a glabrous interval (this on observation is always at the base of the large tufts of hairs), elongated in front to the apical quarter of the labellum; the rest of the labellum glabrous; 5 veined, simple between the 2 keels and 6 branched to the edges, all fine and slightly undulate. Column 14-16 mm tall more than 1.5 mm wide, on the apical surface. Anther thick and bicornute, provided in front with a longer than wide tongue; staminodes wide (2 mm) obscurely crenulate dentate Rostellum in a wide, flat apicule. Stigmas 1.2 mm long, porrect and bidentate apically. Pedicel thin, 4-4.5 cm long. Fruits narrower than those of Vanilla madagascariensis (generally 13 x 1 cm).
In dry deciduous scrub at elevations up to 700 meters.
Flowering in January.
NW. & S. Madagascar
Flora of Madagascar: vascular plants: 49th family, Orchids / by H. Perrier de La Bathie; published under the auspices of the government of Madagascar and under the direction of H. Humbert; English revision and translation by Steven D. Beckman; Orchids of Madagascar Hermans 2007 ; Field Guide to the Orchids of Madagascar Cribb & Herman 2009
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