Perennial, large, aquatic herb; creeping root stock, stem submerged; leaves arising from a perennial rhizome or corm; leaves rotundous, orbicular, 20-40 cm across, often pinnately nerved, entire or toothed, margins undulating, glabrous, blotched with purple beneath, floating on long petioles; flowers 10-15 cm across, blue, white, rose, purple, slightly scented, regular, bisexual, floating on axillary peduncles; sepals 4, many veined, inserted almost at the base of torus, not ribbed or streaked with fine, purple lines; petals indefinite, usually 10-30, lanceolate-oblong, acute or acuminate, inner gradually transforming into stamens, spirally arranged; stamens numerous, anthers small, linear, filaments petaloid; carpels numerous, apocarpus, ovoid, sunk in a fleshy disc, forming a many celled ovary, crowned by the connate, radiating, furrowed stigma, rays 10-30; ovules numerous, anatropous; fruit a spongy berry, ripening under water; seeds many, arillate, substriate.