Description:

• Submerged herbaceous annuals or perennials, monoecious or dioecious, in fresh or brackish water
• Roots simple, adventitious, devoid of root caps
• Branches upright, repeatedly forked, brittle, smooth or prickly
• Leaves sessile, in pseudo-whorls of 3 or more, with an open, folded basal sheath and a linear, 1-veined, dentate lamina, with 2 axillary scales
• Flowers unisexual, small, solitary or sometimes aggregated above, water-pollinated
• Male flower a single stamen enveloped in bud by a closed spathe, with a thin inner membrane, bilobed at apex, closely adhering to the 1- or 2- or 4-thecous anther; pollen globose or ellipsoid, without exine, contents granular
• Female flower a single ovoid carpel surrounded by a spathe, or naked; ovule solitary, basal, erect, anatropous; style filiform, with 2(3) filiform stigmatic branches
• Fruit a small, narrowly ovoid nut; epicarp reticulated
• Seeds: embryo straight, with a large hypocotyl and radicle; endosperm 0
• x = 6 (7, 8, 17, 23) (high polyploidy, B-chromosomes)

Nomenclature:

• Najadaceae
  • Bennett: 41 (1897)
  • Obermeyer: 81 (1966)
  • Cook: 128 (1990)

Distribution & Notes:

• Global: Monogeneric, species ± 40, cosmopolitan except in very cold regions
• Southern Africa: Genus 1, species 4

References:

• BENNETT, A. 1897. Naiadaceae. Flora capensis 7
• COOK, C.D.K. 1990. Aquatic plant book. SPB Academic Publishing, The Hague
• OBERMEYER, A.A. 1966. Najadaceae. Flora of southern Africa 1

Resources:

• Najadaceae genus: Najas