Description:

• Submerged aquatic herbs, perennating by buds, sometimes annual, rootless, branches occasionally modified as 'rhizomes'; monoecious
• Stem branched but not more than 1 branch at a node
• Leaves in whorls, (3-)6-8(-10) at a node, filiform, once or more dichotomously branched, with 2 rows of minute teeth along ultimate segments, apical segments truncate, tipped with two spines; stipules 0
• Flowers unisexual, solitary in axil of 1 leaf in a whorl, male and female usually on alternate nodes; perianth lobes 6-13, united at base, strap-shaped or obovate, margin often with a single hyaline spine or lacerated, apex similar to leaf apex; water-pollinated
• Male flowers subsessile; stamens up to 30 in several whorls on a domed receptacle around pistillode; filaments short or 0; anthers oblong, extrose, 2-thecous, dehiscing longitudinally, immature anthers resembling perianth lobes, margins 1-3-spined; mature anthers detach and float to water surface where they dehisce and shed pollen onto plants below
• Female flowers sessile or shortly pedicellate; staminodes 0; ovary superior, 1-carpellate, 1-locular, ovoid, tapering into a long style; ovule 1, pendulous, unitegmic
• Fruit a 1-seeded nut, ovoid or ellipsoid, tipped by persistent style, often with additional marginal and basal spines, also often warty
• Seed without endosperm
• x = 12 (aneuploids, polyploidy)

Nomenclature:

• Ceratophyllum L.
  • Linnaeus: 325 (1753)
  • Wilmot-Dear: 125 (1997)

Distribution & Notes:

• Southern Africa: Taxa 2 or possibly 3:
  • Ceratophyllum demersum L. var. demersum, in Caprivi (Namibia), N Botswana, Northern Province, Gauteng, Mpumalanga, Swaziland, Free State and coastal regions of KwaZulu-Natal, Western and Eastern Cape; in stagnant to fast-flowing water, tolerant of brackish estuarine water of high salinities but not found in alkaline, temporary pools
  • C. muricatum Cham. subsp. muricatum occurs in Mpumalanga and possibly elsewhere in slow-flowing or stagnant water as well as seasonal, highly alkaline pools, not in brackish estuarine conditions
  • According to Wilmot-Dear (1997) sterile material with 3-4 times dichotomous leaves found in E KwaZulu-Natal and southern coastal regions of Western and Eastern Cape, could possibly be C. submersum L. var. submersum