Description:

• Annual or perennial, often monoecious, rarely dioecious (Burnatia), aquatic or marsh herbs, lactiferous; rhizome woody and irregular or tuberous, suckering or forming runners, bearing winterbuds; roots thin, abundant, branched
• Leaves basal, subdistichous; petioles usually long, expanded below to form an open sheath; blade erect, entire, lanceolate, ovate, hastate or sagittate, rarely floating and/or submerged and then phyllodic, with distinct parallel veins converging to apex and lobes, connected by cross-veins; with an apical hydathode; axillary scales present
• Inflorescence usually thyrsoid with flowers in whorls or in simple compound umbels
• Flowers regular, bisexual and/or unisexual, bractiferous
• Sepals 3, free, green, persistent
• Petals 3 (rarely 0), free, delicate, fugaceous; pollination entomophilous, occasionally cleistogamous
• Stamens 3-many, free; filaments filiform or expanded below; anthers 2-thecous, basifixed; pollen sphaeroid; staminodes present in some species
• Ovary superior; carpels 3-many, free, if many, situated on a flat or convex receptacle, arranged spirally or in a ring, unilocular; ovule 1; style terminal or ventral; stigma apical; in unisexual male flowers sterile carpels may be present
• Fruit 3-many achenes, buoyant
• Seeds with a horseshoe-shaped embryo; endosperm 0

Nomenclature:

• Alismataceae
  • Carter: 1 (1960)
  • Obermeyer: 96 (1966)
  • Cook et al.: 99 (1974)
  • Dahlgren et al.: 301 (1985)
  • Cook: 25 (1990)

Distribution & Notes:

• Global: Genera 11 or 12, species ± 100, mainly northern hemisphere, subcosmopolitan, with most taxa present in the tropics and subtropics
• Southern Africa: Genera 5, species 6

References:

• CARTER, S. 1960. Flora of tropical East Africa. Alismataceae
• COOK, C.D.K., GUT, B.J., RIX, E.J., SCHNELLER, J. & SEITZ, M. 1974. Water plants of the world. W. Junk, The Hague
• COOK, C.D.K. 1990. Aquatic plant book. SPB Academic Publishing, The Hague
• DAHLGREN, R.M.T., CLIFFORD, H.T. & YEO, P.F. 1985. The families of the monocotyledons. Springer-Verlag, Berlin
• OBERMEYER, A.A. 1966. Alismataceae. Flora of southern Africa 1

Resources:

• Key to Alismataceae genera

• Alismataceae genera: