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FNA | Family List | FNA Vol. 26 | Dioscoreaceae | Dioscorea

2. Dioscorea floridana Bartlett, U.S.D.A. Bur. Pl. Industr. Bull. 189: 18. 1910.

Dioscorea villosa Linnaeus subsp. floridana (Bartlett) R. Knuth; D. villosa var. floridana (Bartlett) H. E. Ahles

Plants rhizomatous; rhizomes yellow, unbranched, horizontal, 0.5–1 cm or more diam., nodes articulate, each segment bearing 1 dark, contrasting, ± deltate scale leaf, scales brown and papery, caducous, each leaving dark, linear scar perpendicular to growing axis. Stems twining counterclockwise, ± polygonal to terete, 1–4 m, surface longitudinally grooved. Leaves alternate proximally (variation expected) and distally, 3–11 × 3–9 cm; petiole 3–8 cm, base not clasping; blade sometimes glandular, 7–9-veined, ovate-cordate to deltate, glabrous, margins entire or repand, apex acuminate. Staminate inflorescences (1–)2–5 in leaf axils, terminal, spicate to highly branched; cymes sessile, bearing 1–3 sessile flowers, bracteolate, internodes between cymes 2–5 mm, bracteoles linear-lanceolate, ca. 1 mm; rachis to 30 cm, secondary axes to 15 cm, subtended by linear-lanceolate bracts ca. 1–2 mm. Pistillate inflorescences borne singly, 4–20 or more-flowered, 4–25 cm, internodes 7–12 mm. Staminate flowers: perianth yellowish orange, rotate-campanulate to funnelform, 1–2 mm; tepals ± glandular, oblong, margins hyaline, apex (acute to) rounded or truncate; stamens in 2 equal whorls, inwardly curved; anthers ca. 1/3 length of filaments, thecae connate. Pistillate flowers: perianth as in staminate flowers; staminodes 6, differentiated into anthers and filaments, less than 1/2 size of fertile stamens. Capsules greenish gold, ovoid, obreniform, or oblong, 1.5–2.8 × 1.5–2.5 cm. Seeds 9–13 mm.

Flowering late spring--mid summer; fruiting late summer. Edges of swamps, in hammocks, moist and dry (pine) forests and forest margins, sandy soils, lowlands; 0--100 m; Fla., Ga., S.C.

Dioscorea floridana is undoubtedly a close relative of D. villosa, but because it is identifiable using characters that vary discretely, with states not manifest in plants occupying similar habitats outside of its range, I have chosen to retain it at the rank of species.


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