Description:

• Aquatic, perennial or annual, glabrous, erect herbs with sympodially branching rhizomes or stems, rooting or free-floating
• Leaves alternate or in basal rosettes; petioles usually sheathing, often long, sometimes inflated with aerenchyma, often dimorphous: lamina of emergent leaves expanded with parallel, curved-convergent veins, submerged leaves linear; sheaths sometimes ligulate; stipule-like structures sometimes present
• Flowers bisexual (sometimes cleistogamous), ± regular to irregular, solitary or in terminal spikes or racemes subtended by a spathe-like sheath, ebracteate; usually insect-pollinated
• Perianth 3 + 3, petaloid, usually forming a short tube; blue, white or yellow, marcescent
• Stamens 3 + 3, 3 or 1 (in cleistogamous flowers); filaments free, arising on perianth tube at different levels; anthers 2-thecous, dorsifixed or basifixed, opening by longitudinal or apical (Monochoria) slits
• Ovary superior, of 3 fused carpels, ± completely 3-locular, with many ovules on intruding parietal to axile placentas, or, by reduction, 1-locular with 1 pendulous ovule (Pontederia); style filiform, sometimes of 3 different lengths (tristylous; e.g. in Pontederia); stigma entire or shortly lobed
• Fruit a loculicidal, thin-walled capsule or a nut (Pontederia)
• Seeds small, ovoid, longitudinally ribbed; embryo cylindrical; endosperm starchy, copious

Nomenclature:

• Pontederiaceae
  • Brown: 1 (1897)
  • Podlech: 1 (1969)
  • Dahlgren et al.: 340 (1985)
  • Obermeyer: 61 (1985)
  • Cook: 193 (1990)

Distribution & Notes:

• Global: Genera 9, species ± 36, widespread in tropics and subtropics
• Southern Africa: Genera 4, species 4

References:

• BROWN, N.E. 1897. Pontederiaceae. Flora capensis 7
• 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. 1985. Pontederiaceae. Flora of southern Africa 4,2
• PODLECH, D. 1969. Pontederiaceae. Prodomus einer Flora von Südwestafrika 154

Resources:

• Key to Pontederiaceae genera

• Pontederiaceae genera: