Common Vines & Climbing Plants of Puerto Rico and the Virgin Islands

Dioscorea alata L., Sp. Pl. 1033. 1753.

Fig. 174. A-E

Synonym: Rajania flexuosa Bello

Non-woody vine, twining (toward the right), glabrous, attainig 10-15 m in length. Stems quadrangular, with 4 longitudinal projections, winged, undulate, green or reddish; mature stems (at the base) cylindrical and spiny. Leaves mostly opposite, sometimes alternate on branches of rapid growth, coriaceous, broadly ovate, 5-7-veined, 10-30 × 5-18 cm, the apex acute or acuminate, sometimes reflexed, the base cordiform; upper surface dark green, shiny, with the venation sunken; lower surface pale green, dull, with prominent venation; petioles 4-12 cm long, 4-winged, forming an auriculate sheath at the base, with a pair of pseudostipules that enclose the stem; bulbils elongate, pendulous, attaining 15 cm long, produced when the leaves begin to wither. Inflorescences axillary, unisexual, pendulous; the staminate ones paniculate, 5-15 cm long, with numerous lateral and flexuous spikes that contain numerous male flowers; the pistillate ones racemose, with few flowers. Staminate flowers with the perianth 1-1.5 mm long; pistillate flowers with the perianth 2-2.8 mm long. Capsule 3-locular, 2-3 cm wide, each locule flattened like a wing, with two seeds inside.

Phenology: Collected in flower in October and November and in fruit in January.

Status: Exotic, naturalized, rather common.

Selected Specimens Examined: Acevedo-Rdgz., P. 7047; 7076; Goll, G.P. 137; 1066; Sargent, F.H. B48; Sintenis, P. 448; 4509; Stevenson, J.A. 2100; Underwood, L.M. 358.
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