Hermaphrodite, perennial. Stems very shortly rhizomatous, or erect and corm-like, simple or forked, up to 1 cm. in diameter. Leaves radical, linear to lanceolate, 2–35(–60) cm. long, 2–8(–12) mm. wide, attenuate to a narrowly acute or acuminate tip, patent or erect, mid-green to dark green, with up to 28 longitudinal veins and faint cross-veins. Flowers bisexual. Spathe: peduncle up to 50 cm. long; body of spathe 4–12 cm. long, 1.5–3 mm. wide, 6-nerved, with 1(–2) flowers. Sepals 5–10 mm. long, ± 1.2 mm. wide, green, often streaked with purple; petals linear, often twisted and folded between the sepals, ± 17 mm. long, ± 0.5 mm. wide, acute, white or reddish; stamens 3, up to 4 mm. long; anthers 1–1.8 mm. long, with a distinct connective-tip up to 1 mm. long; filaments ± 2 mm. long; ovary 40–55 mm. long, ± 1.5 mm. wide, greenish brown; perianth-tube narrowly cylindric, up to 15 cm. or more long; stigmas 10–15 mm. long, white or reddish. Fruit 40–60(–80) mm. long, 1.5–3 mm. wide, brown. Seeds ellipsoid or ovoid, 1.2–2 mm. long, 0.6–0.8 mm. wide, smooth or ribbed wihout spines, or ribbed and spiny with apical and basal spines up to 5 mm. long, light brown.
in Mém. Cl. Sci. Math. Phys. Inst. France, 1811(2): 19, 77, t. 4 (1812, published 1814); Cook & Lüönd in Aquat. Bot. 15: 9 (1983).