Description: Submerged perennial herbs with slender stems, unattached or attached to the substrate.
Leaves whorled, sessile, palmately to dichotomously dissected.
Flowers axillary, solitary, sessile, small, unisexual and plants monoecious. Flowers surrounded by an involucre of bracts. Male flowers with numerous stamens on a common axis. Female flowers with a single superior ovary.
Fruit a 1-seeded nut, topped by the persistent style; bracts may remain attached to the base of the fruit. The single genus Ceratophyllum is found in fresh waters in most parts of the world.
Distribution and occurrence: World: 1–30 species, cosmopolitan. Australia: 1 or 2 species, all mainland States.
Text by S. W. L. Jacobs
Taxon concept:
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