Plants annual. Vegetative stems submersed with elongate inter-nodes, or emersed and procumbent. Flowering stems 1–4 cm, distal internode less than 1 cm. Sessile leaves alternate; blade linear to oblanceolate, thin, 37–70 × 4–6 mm, margins entire. Petiolate leaves floating or emersed; stipule 3–5 cm; petiole 5–15 cm; blade cordate, 2–5 × 2–5 cm, length usually greater than width, apex obtuse. Inflorescences spicate, 3–16-flowered, elongating in 1–2 days, longer than spathes (except on cleistogamous inflorescences); spathes 2–7 cm, glabrous; peduncle 4–11 cm, glabrous when emersed. Flowers opening ca. 2 hours after dawn, wilting early afternoon; perianth mauve or white, salverform, tube 3–12 mm, limbs zygomorphic, lobes narrowly elliptic, 3.3–5.9 mm, distal central lobe dark purple in basal 1/3, 2 yellow spots within dark area; stamens unequal, lateral stamens 1.3–2.4 mm, filaments linear, densely pubescent with purple multicellular hairs toward apex; central stamen 2.6–4 mm, filament sparsely pubescent with multicellular hairs; style pubescent with multicellular hairs. Seeds 9–12-winged, 0.6–0.9 × 0.4–0.5 mm. 2n = 32.
