Nymphoides montana

Perennial; stems to 2 m long, floating, stoloniferous. Petioles of basal leaves to 70 cm long; blades c. circular, rarely very broad-ovate, entire or rarely slightly crenate, deeply cordate, green above, 2.5–11 cm long. Flowers heterostylous, in spaced pairs along a short inflorescence; calyx (5–)6–8(–10) mm long; corolla 23–38 mm diam., lobes 5(–6), with broad laciniate wings, not keeled; stigmas 2. Capsule 5.5–9 mm long, equal to or slightly longer than calyx; seeds ellipsoid, strongly laterally compressed, 1.1–1.6 mm long, black when mature, smooth or rarely with minute obtuse domes or tubercles less than twice as long as wide; caruncle circular, thin, pale. Flowers and fruits mostly Dec.–Mar.