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. A cosmopolitan distribution is a term applied to a biological category of living things meaning that this category can be found anywhere around the world. ... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants or angiosperms are the most widespread group of land plants. ... This is an article about the non-vascular plants known as hornworts. ...

Ceratophyllum grows completely submerged, usually though not always floating on the surface, it doesn't tolerate drought. The plant stems can reach over a meter in length. At intervals along nodes of the stem they produce rings of bright green leaves, which are narrow and often branched. The forked leaves feel brittle and stiff to the touch. 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 don't attract attention, with the male and female flowers on the same plant. In ponds it forms thick buds 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.

Because of their appearance and their high oxygen production, they are often used in freshwater aquaria. Hornwort plants float in great numbers just under the surface. They offer excellent protection to fish-spawn, but also to snails, infected with bilharzia. “Aquaria” redirects here. ... Schistosomiasis Schistosomiasis or bilharzia is a disease affecting many people in developing countries. ...

Relationships and classification

Ceratophyllum is considered unique enough to warrant its own family, Ceratophyllaceae, and its precise relationship to other angiosperms remains unclear. It was considered a relative of Nymphaeaceae and included in Nymphaeales in the Cronquist system but recent research has shown that it is not closely related to Nymphaeaceae or any other extant plant family. Some early molecular phylogenies suggested it was the sister group to all other angiosperms, but more recent ones have suggested that it is the sister group to either the monocots or the eudicots. The APG II system places the family in its own order, the Ceratophyllales. Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants (also angiosperms or Magnoliophyta) are one of the major groups of modern plants, comprising those that produce seeds in specialized reproductive organs called flowers, where the ovulary or carpel is enclosed. ... genera see text Nymphaeaceae is the botanical name of a family of flowering plants. ... Families Cabombaceae - fanworts Nymphaeaceae - water lilies The Nymphaeales are an order of flowering plants, including two families of aquatic herbs: Family Nymphaeaceae (waterlily family) Family Cabombaceae (fanwort family) Sometimes the Cabombaceae are included within the Nymphaeaceae. ... A system of plant taxonomy, the Cronquist system is a scheme for the classification of flowering plants (or angiosperms). ... This cladogram shows the relationship among various insect groups. ... Orders Base Monocots: Acorus Alismatales Asparagales Dioscoreales Liliales Pandanales Family Petrosaviaceae Commelinids: Arecales Commelinales Poales Zingiberales Family Dasypogonaceae Monocotyledons or monocots are a group of flowering plants usually ranked as a class and once called the Monocotyledoneae. ... In the APG-system, the names eudicots or tricolpates are applied to a monophyletic group that includes most of the (former) dicotyledons. ... The Angiosperm Phylogeny Group is an international group of systematic botanists who have come together to try to establish a consensus view of the taxonomy of flowering plants in the light of the rapid rise of molecular systematics. ...

The division of the genus into species is not completely settled. There are two main species:

• Ceratophyllum demersum - Common Hornwort or Rigid Hornwort
• Ceratophyllum submersum - Tropical Hornwort

Ceratophyllum demersum

More than 30 other species have been described, but many of them are probably mere variants of these. Common Hornwort (Ceratophyllum demersum) Downloaded from : [[1]] Credits USGS - Northern Prairie Wildlife Research Center File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Common Hornwort (Ceratophyllum demersum) Downloaded from : [[1]] Credits USGS - Northern Prairie Wildlife Research Center File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

External links

• Ceratophyllales (Angiosperm Phylogeny Web)

Ceratophyllum demersum