Description :

• 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)

Nomenclature:

• Ottelia Pers.
  • Persoon: 400 (1805)
  • Obermeyer: 108 (1966)
  • Cook et al.: 263 (1984)
  • Cook: 102 (1990)

Distribution & Notes:

• Global : Species 21, tropics and subtropics, 13 in Africa, 7 in Asia and Australia and 1 in South America
  • * Ottelia alismoides (L.) Pers. has spread out of Asia and has naturalised in Africa, Europe and North America
• Southern Africa : Species 4, restricted to the warmer parts

Additional Notes:

• Seeds embedded in pulp (rather like bananas), dispersed by water, fish and perhaps other animals