Dioecious, annual or rarely perennial.. Stems erect, corm-like, simple or shortly rhizomatous.. Juvenile leaves not seen; mature leaves petiolate; blade submerged, elliptic, elliptic-oblong or elliptic-ovate, 8.4–16 cm. long, (4.5–)6–9.4 cm. wide, obtuse, or rounded, cuneate at base, mid-green to dark green, with 5–9 prominent, longitudinal, veins connected by ascending cross-veins, together with many smaller longitudinal veins; margins entire; petiole up to 38 cm. long, 0.4–0.8 cm. wide, somewhat winged in the lower half.. Nodal scales not seen.. Flowers unisexual.. Male spathe: peduncle 18–28 cm. long, 0.4–1.3 cm. wide; body of spathe submerged, slightly inflated, oblong to ovate, 7–10 cm. long, 1.7–3.2 cm. wide, 2–4-lobed at the apex, 0–2-winged, green.. Male flowers pedicellate, up to 15 per spathe; pedicels up to 12 cm. long; sepals linear-lanceolate or lanceolate, 1.6–2.9 mm. long, ± 4 mm. wide, obtuse to subacute, membranous, whitish; petals broadly obovate, 4–4.8 cm. long, ± 2 cm. wide, broadly obtuse, white or yellowish; stamens up to 10; anthers 4–6 mm. long, yellowish; filaments 0.5–1.6 mm. long, papillose, purplish; staminodes 3, linear, up to 2 cm. long, united towards the base.. Female spathe: peduncle 30 cm. long, 0.6–1.2 cm. wide; body of spathe submerged, not or slightly inflated, oblong, 4.5–6 cm. long, 0.8–1.5 cm. wide, 2–4-lobed at the apex, 0–2-winged and with several longitudinal ribs or veins, green, the ribs sometimes purplish.. Female flowers 1 per spathe; sepals linear-lanceolate or lanceolate, 2–3.2 cm. long, 4–5 mm. wide, acute to obtuse, rarely cucullate, green, the margins often hyaline; petals broadly obovate to suborbicular, 3.8–6 cm. long, 4–5 cm. wide, broadly obtuse, or rounded, white; ovary not seen; styles up to 10; stigmas up to 20, 15–17 mm. long, yellowish.. Fruit and seeds not seen.. Fig. 7, p. 18.
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