Common name. Water-lily Family.
Habit and leaf form. Aquatic herbs; laticiferous. Perennial; rhizomatous. Hydrophytic; rooted. Leaves floating; medium-sized to large; alternate; spiral; petiolate; simple; usually more or less peltate. Leaf blades entire; usually more or less orbicular; basically palmately veined; cross-venulate; usually cordate. Leaves with stipules (the stipules median-axillary), or without stipules; without a persistent basal meristem. Stem anatomy. Secondary thickening absent.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous.
Inflorescence and flower features. Flowers solitary; large; often fragrant; regular; partially acyclic. The perianth acyclic and the androecium acyclic. Free hypanthium absent. Perianth with distinct calyx and corolla (e.g. Nymphaea, according to the usual interpretation), or petaline (Nuphar); 5, or 20–50 (‘many’); free. Calyx as commonly interpreted 4, or 5; polysepalous; imbricate. Corolla 5 (Nuphar), or 15–50 (‘many’, showy); polypetalous; imbricate. Androecium 40–80. Androecial members maturing centripetally; free of the perianth; free of one another; spiralled. Androecium including staminodes (with transition from petals to stamens). Staminodes 11–20 (in the form of nectariferous scales, in Nuphar); in Nuphar, petaloid. Stamens 40–80; petaloid, or laminar, or filantherous (in sequence). Anthers adnate; non-versatile; dehiscing via longitudinal slits; introrse; locule number?; tetrasporangiate. Pollen shed as single grains. Gynoecium 5–35 carpelled. The pistil 5–35 celled. Gynoecium syncarpous; eu-syncarpous; superior to partly inferior. Ovary plurilocular; 5–35 locular. Placentation more or less parietal (or ovules more or less scattered). Ovules 10–100 per locule (i.e. ‘many’); arillate, or non-arillate; orthotropous, or anatropous.
Fruit and seed features. Fruit fleshy; dehiscent, or indehiscent, or a schizocarp (Nuphar); when non-schizocarpic, a berry; enclosed in the fleshy receptacle. Seeds endospermic. Perisperm present. Cotyledons 1, or 2. Embryo chlorophyllous (2/2); straight. Seedling. Germination cryptocotylar.
Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C3.
Geography, cytology, number of species. World distribution: cosmopolitan, except in frigid zones. 75 species.
T.D. Macfarlane, L. Watson, N.G. Marchant