Ottelia

Aquatic, rooted, +/- stemless, armed or unarmed annuals, dioecious or monoecious or sometimes flowers bisexual; roots many, simple. Leaves rosulate, sessile or petiolate, sheathing at base, submerged or in some species also with floating blades; lamina of submerged leaves ribbon-like, linear to lanceolate, with floating blade ovate to cordate; nerves 3-11, distinct, connected by cross-veins. Inflorescence pedunculate; spathes saccate, containing many male flowers; female and bisexual flowers usually solitary; spathes firm, with prominent, sometimes muricate, ribs or wings, or occasionally smooth. Flowers: perianth white or yellow, tubular, with 3 outer segments sepaloid, persistent, and 3 inner larger, petaloid, slightly exserted above surface of water at anthesis, ephemeral; pollination entomophilous (or flowers often cleistogamous). Male flowers usually 1-3 exserted at a time, with pedicels lengthening rapidly at anthesis; stamens 6-15; anthers basifixed; pollen globular, tuberculate; gynoecium rudimentary. Female flowers: ovary flask-shaped with 3-6 parietal placentas intruding towards centre; styles 3-15, each divided into 2 stigmatic arms; ovules many, amphitropous; staminodes present or 0. Fruit ripening inside accrescent spathe; lower part of perianth tube forming its beak. Seeds many, small, fusiform, tomentose or glabrous, many released in pulpy mass. x = 11 (10, 12, 17, 26) (aneuploids, high polyploidy).