Ceratophyllum demersum

Life-forms

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Ordo: Ceratophyllales

Familia: Ceratophyllaceae
Genus: Ceratophyllum
Species: Ceratophyllum demersum
Name

Ceratophyllum demersum L. Sp. Pl. 992. (1753)

Type locality: various localities

Synonyms

Homotypic
Ceratophyllum cornutum Rich. ex S.F. Gray, Nat. Arr. Brit. Pl. 2: 555 555. (1821)
Dichotophyllum demersum (L.) Moench Methodus 345. (1794)

References

Linnaeus, C. 1753. Species Plantarum. Tomus II: 992. Reference page.
Riehl, R. & Baensch, H.A. 2001. Atlas de l’aquarium. 14th edition, volume 1, p. 88–89. ISBN 3-88244-049-X. Reference page.

Vernacular names
العربية: شمبلان مغمور
azərbaycanca: Suyabatmış buynuzyarpaq
català: Llapó punxenc
čeština: Růžkatec ponořený
Cymraeg: Cyrnddail caled
Deutsch: Raues Hornblatt
English: Rigid Hornwort
español: Mil hojas de agua
eesti: Räni-kardhein
suomi: Karvalehti
français: Cornifle immergé
hornjoserbsce: Drapaty rohačk
italiano: Ceratofillo
日本語: マツモ
한국어: 붕어마름
lietuvių: Paprastoji nertis
മലയാളം: കരിംപായൽ
Nederlands: Grof hoornblad
norsk: Hornblad
polski: Rogatek sztywny
русский: Роголистник погружённый
slovenčina: Rožkatec ponorený
svenska: Hornsärv
українська: Роголисник занурений
Tiếng Việt: Rong đuôi chó
中文（简体）: 金鱼藻
中文（繁體）: 金魚藻
中文（臺灣）: 金魚藻
中文: 金鱼藻

Ceratophyllum demersum, commonly known as hornwort, rigid hornwort,[1] coontail, or coon's tail,[2] is a species of Ceratophyllum. It is a submerged, free-floating aquatic plant, with a cosmopolitan distribution, native to all continents except Antarctica. It is a harmful introduced weed in New Zealand.[2] It is also a popular aquarium plant.

Description

An aquatic plant, Ceratophyllum demersum has stems that reach lengths of 1–3 m (3–10 ft), with numerous side shoots making a single specimen appear as a large, bushy mass. The leaves are produced in whorls of six to twelve, each leaf 8–40 mm long, simple, or forked into two to eight thread-like segments edged with spiny teeth; they are stiff and brittle. It is monoecious, with separate male and female flowers produced on the same plant. The flowers are small, 2 mm long, with eight or more greenish-brown petals; they are produced in the leaf axils. The fruit is a small nut 4–5 mm long, usually with three spines, two basal and one apical, 1–12 mm long. Plants with the two basal nut spines very short are sometimes distinguished as Ceratophyllum demersum var. apiculatum (Cham.) Asch., and those with no basal spines sometimes distinguished as Ceratophyllum demersum var. inerme Gay ex Radcl.-Sm.[3][4][5][6][7] It can form turions: buds that sink to the bottom of the water that stay there during the winter and form new plants in spring.
Distribution and habitat

Ceratophyllum demersum grows in lakes, ponds, and quiet streams with summer water temperatures of 15-30 °C and a rich nutrient status. In North America, it occurs in the entire US and Canada, except Newfoundland.[8] In Europe, it has been reported as far north as at a latitude of 66 degrees in Norway.[9] Other reported occurrences include China, Siberia (at 66 degrees North), Burkina Faso and in the Volta River in Ghana (Africa), Vietnam, and New Zealand (introduced).[10] Ceratophyllum demersum grows in still or very slow-moving water.
Invasive status

Hornwort is a declared weed under the Tasmanian Weed Management Act 1999 in Tasmania, Australia,[11] and is classed as an unwanted organism in New Zealand.[12]
Ecology

C. demersum has allelopathic qualities as it excretes substances that inhibit the growth of phytoplankton and cyanobacteria (blue-green algae).[2][13] Its dense growth can outcompete native underwater vegetation, leading to loss of biodiversity. In New Zealand, it has caused problems with hydroelectric power plants.[2]
Cultivation and uses

This species is often used as a floating freshwater plant in both coldwater and tropical aquaria. Though without roots, it may attach itself to the substrate or objects in the aquarium. Its fluffy, filamentous, bright-green leaves provide excellent cover for newly hatched fish. It is propagated by cuttings.[14] It is frequently used as a model organism for studies of plant physiology.[15] One of the reasons for this is that it allows studies on shoot effects without influence of a root, which often makes interpretation of nutrition and toxicity experiments difficult in terrestrial plants. As it is free floating and therefore does not require a solid substrate, it has been used successfully in the biological life support systems "Aquarack/CEBAS" and "Omegahab" on space flights [16][17][18] Hornwort plants or the epiphytes they support have been shown to degrade the herbicide atrazine.[19]

In aquaria this plant appears to drop all its leaves when exposed to products designed to kill snails. The stems can recover relatively quickly, growing new leaves within a few weeks.
References

BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-06-26. Retrieved 2014-10-17.
Ceratophyllum demersum on the Global Invasive Species database (2006).
Flora of China: Ceratophyllum demersum
Flora of North America: Ceratophyllum demersum
Flora of NW Europe: Ceratophyllum demersum
Blamey, M. & Grey-Wilson, C. (1989). Flora of Britain and Northern Europe. ISBN 0-340-40170-2
Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan ISBN 0-333-47494-5.
USDA PLANTS database on C. demersum as of 2011.
ISSG database, reports in Norway (based on Mjelde, 1997)
ISSG: distribution of C. demersum
"Hornwort". Department of Primary Industries, Parks, Water and Environment. Retrieved 21 September 2012.[dead link]
"Hornwort". MPI Biosecurity New Zealand. 29 May 2012. Archived from the original on 5 December 2012. Retrieved 21 September 2012.
"Cyanobacteria (Blue-green Algae)".
Hiscock, P. (2003). Encyclopedia of Aquarium Plants. Interpret Publishing, United States and Canada ISBN 0-7641-5521-0.
"Google Scholar".
Blüm V, Stretzke E, Kreuzberg K (1994) CEBAS-aquarack project - the mini-module as tool in artificial ecosystem research. Acta Astronautica 33: 167–177
Voeste D, Levine LH, Levine HG, Blüm V (2003) Pigment composition and concentrations within the plant (Ceratophyllum demersum L.) component of the STS-89 C.E.B.A.S. Mini-Module spaceflight experiment. Advances in Space Research 31, 211-214
"Landing of Bion-M No. 1 satellite". Archived from the original on 2013-06-09. Retrieved 2013-05-20.
Rupassara, S. I., R.A. Larson, G.K. Sims, and K.A. Marley. 2002 Degradation of atrazine by hornwort in aquatic systems. Bioremediation Journal 6(3): 217-224.