  ceratophyllum is a cosmopolitan genus of flowering plants, commonly found in ponds, marshes, and quiet streams in tropical and in temperate regions. they are usually called hornworts, although this name is also used for unrelated plants of the division anthocerotophyta.kew world checklist of selected plant families ceratophyllum grows completely submerged, usually, though not always, floating on the surface, and does not tolerate drought. the plant stems can reach 1â3 m in length. at intervals along nodes of the stem they produce rings of bright green leaves, which are narrow and often much-branched. the forked leaves are brittle and stiff to the touch in some species, softer in others. the plants have no roots at all, but sometimes they develop modified leaves with a rootlike appearance, which anchor the plant to the bottom. the flowers are small and inconspicuous, with the male and female flowers on the same plant. in ponds it forms thick buds (turions) in the autumn that sink to the bottom which give the impression that it has been killed by the frost but come spring these will grow back into the long stems slowly filling up the pond.flora of china: ceratophyllumflora of north america: ceratophyllumblamey, m. & grey-wilson, c. (1989). flora of britain and northern europe. isbn 0-340-40170-2huxley, a., ed. (1992). new rhs dictionary of gardening. macmillan isbn 0-333-47494-5. hornwort plants float in great numbers just under the surface. they offer excellent protection to fish-spawn, but also to snails, infected with bilharzia. because of their appearance and their high oxygen production, they are often used in freshwater aquaria. ==relationships and classification== ceratophyllum is
Angiosperm_genera Angiosperms Freshwater_plants