Aponogeton

Rhizomatous glabrous monoecious or rarely dioecious herbs with tubers, usually growing submerged in fresh water or (after drying up) on wet soil. Leaves all basal and alternate, simple and usually with long petioles; blades oblong to linear. Inflorescence usually a simple or bifid spike (rarely the spike digitate and divided into 3–4 parts), at first enclosed in a thin caducous spathe, very rarely (in the South African species A ranunculiflorus ) the inflorescence is much abbreviated simulating A Ranunculus flower. Flowers bisexual or more rarely unisexual. Tepals 1–6 or absent, petal-like, often persisting in fruit. Stamens 1–6, rarely more; filaments free, filiform or flattened; anthers extrorse, 2-thecous, most often only 0.2–0.5 mm. long. Ovaries 3–8, free or slighdy united near their base; each ovary superior and 1-locular, with 1–14 erect ovules borne along one side of the locule-wall or at the base of the locule. Fruit a 1–14-seeded follicle. Seeds discoidal to fusiform, straight or slightly curved, with a simple or double testa; endosperm absent.