Ceratophyllum demersum L., Ceratophyllaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

Chinese: jin yu zao

English: common coontail, coontail, hornwort

Fijian: lumilumi

Filipino: arigman

French: cératophylle submergé

Japanese: matsumo

Spanish: cama de ranas, cola de zorro

Tagalog: inata

Habit:  aquatic herb

Description:  "A submerged, rootless, densely leafy, perennial, freshwater plant, stems often much-branched, forming large masses, flexuous, the internodes 1 to 3 cm long; leaves in whorls of seven to 10, 1 to 4 cm long, the base gradually or abruptly thickened above the middle, the segments spreading when submerged, collapsing out of water, twice or thrice forked with linear segments; flowers very small, sessile in the leaf axils, each surrounded by minute bracts, a real perianth not present; flower bracts nine to 12, linear, transparent, with numerous short, brown lines; female flowers with a minute ovary and simple style; male flower, anthers white, stamens sessile; fruit black, 4 to 5 mm long, with three spines, the apical spine (style) 11 to 12 mm long, soft, the two basal ones straight to slightly recurved, 9 to 11 mm long, one-seeded.  This submerged plant is distinguished by the presence of one apical and two basal spines on the fruit and its rootless branched stems with forked leaf segments"  (Holm et al., 1977; p. 207).

"Plants entirely submerged; stems brittle or cord-like and flexuous, 0.5-3 m long, branched, forming large masses.  Leaves of seedlings simple, otherwise in whorls of 3-12 per node and dichotomously dissected, variable in length, often 1-2 cm long, ultimate divisions linear.  Style 4-6 mm long.  Achenes ellipsoid, compressed, 4-6 mm long, wingless, with 2 basal spines 2-5 mm long" (Wagner et al., 1999; p. 533).

Habitat/ecology:  "The plant is an inhabitant of shallow ponds, tanks, lakes and stagnant water.  It tends to seek sheltered sites in standing or slowly flowing water where bottoms are much silted.  There are some records of growth in 10 m of water" (Holm et al., 1977; p. 207).

In Hawai‘i, "naturalized in ponds and reservoirs" (Wagner et al., 1999; p. 533). In Fiji, "found near sea level in swamps and ponds and also at the edges of fast-flowing streams and rivers, sometimes associated with Potamogeton crispus (Smith, 1981; p. 148).

Propagation:  Seed, spread by water and birds (Staples et al., 2000; p.65). "Birds are known to fly with pieces of the plant for short distances.  Strong winds, strong currents, foraging animals, or any violent disturbance of the water may tear the plants into many pieces, each of which is a viable source of a new plant"  (Holm et al., 1977; p. 210).  Often used as an aquarium plant (Smith, 1981; p. 148).

Native range:  Cosmopolitan (Wagner et al., 1999; p. 533). "In the Pacific, distribution of the species is spotty; its occurrence in Hawaii is thought to be due to the escape of cultivated plants (Smith, 1981; p. 148).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Fiji Fiji Islands	Viti Levu Island	probably native	Smith, Albert C. (1981) (p. 148) Vouchers cited: DA 3471, DA 16611, DA 16621, DA 16611, DA 16624, Seemann 386
Guam Guam Island	Guam Island	native	Stone, Benjamin C. (1970) (p. 276) Voucher cited: Stone 4974 (GUAM), Stone 5019 (GUAM)
Guam Guam Island	Guam Island	native	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 76)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 533)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 533) East Maui
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Oppenheimer, Hank L./Bartlett, Randal T. (2002) (p. 5) West Maui. Voucher cited: Oppenheimer H109906 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Staples, George W./Imada, Clyde T./Herbst, Derral R. (2002) (p. 7) Voucher cited: E. Funk s.n. (BISH 666283)
Japan (offshore islands) Bonin (Ogasawara) Islands	Bonin (Ogasawara) Islands		Kato, Hidetoshi (2007)
Papua New Guinea Bismarck Archipelago	Bismarck Archipelago		Peekel, P. G. [translated by E. E. Henty] (1984) (p. 177) In ponds, pools and slow-flowing creeks.
Papua New Guinea Bougainville Islands	Bougainville Island		Foreman, D. B. (1971) (p. 36)
Philippines Philippine Islands	Philippine Islands		Waterhouse, D. F. (1993) (p. 64)
Philippines Philippine Islands	Philippine Islands		Merrill, Elmer D. (1923) (p. 141) In shallow lakes and slow streams.
Solomon Islands Solomon Islands	Solomon Islands	native	Hancock, I. R./Henderson, C. P. (1988) (p. 56)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	Queensland	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 209)
Chile (continental) Chile	Chile (Republic of)		Hafliger, Toni J./Wolf, Matthias (1988) (p. 45)
China China	China (People's Republic of)	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2011) "Streams, ponds, lakes".
China China	Hong Kong	native	Wu, Te-lin (2001) (p. 51)
Colombia Colombia	Colombia (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 78)
Indonesia Indonesia	Indonesia (Republic of)		Waterhouse, D. F. (1993) (p. 64)
Japan Japan	Japan (country)		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 209)
South Korea South Korea	South Korea (Republic of)		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 209)
Malaysia Malaysia	Malaysia (country of)		Waterhouse, D. F. (1993) (p. 64)
Mexico Mexico	Mexico (United Mexican States)		Hafliger, Toni J./Wolf, Matthias (1988) (p. 45)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 515) "Drains, lakes, lagoons, slow-moving rivers".
Panama Panama	Panama (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 78)
Taiwan Taiwan	Taiwan Island		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 209)
Thailand Thailand	Thailand (Kingdom of)		Waterhouse, D. F. (1993) (p. 64)
Vietnam Vietnam	Vietnam (Socialist Republic of)		Waterhouse, D. F. (1993) (p. 64)

Additional information:
Information from the Global Invasive Species Database.

Additional online information about Ceratophyllum demersum is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Ceratophyllum demersum as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Ceratophyllum demersum may be available from the Germplasm Resources Information Network (GRIN).

References:

Foreman, D. B. 1971. A check list of the vascular plants of Bougainville, with descriptions of some common forest trees. Botany Bulletin No. 5. Division of Botany, Department of Forests. Lae, New Guinea. 194 pp.

Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce. 1979. A geographical checklist of the Micronesian dicotyledonae. Micronesica 15:1-295.

Hafliger, Toni J./Wolf, Matthias. 1988. Dicot weeds, vol. 1. CIBA-GEIGY Ltd., Basle, Switzerland. 335 pp.

Hancock, I. R./Henderson, C. P. 1988. Flora of the Solomon Islands. Research Bulletin No. 7. Ministry of Agriculture and Lands, Honiara. 203 pp.

Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. 1977. The world’s worst weeds: distribution and biology. East-West Center/University Press of Hawaii. 609 pp.

Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. 1979. A geographical atlas of world weeds. John Wiley & Sons, New York. 391 pp.

Kato, Hidetoshi. 2007. Herbarium records of Makino Herbarium, Tokyo Metropolitan University. Personal communication.

Merrill, Elmer D. 1923. An enumeration of Philippine flowering plants, vol. 2 [reprint]. Bureau of Printing, Manila. 530 pp.

Oppenheimer, Hank L./Bartlett, Randal T. 2002. New plant records from the main Hawaiian Islands. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 2000. Part 2: Notes. Bishop Museum Occasional Papers. 69:1-14.

Peekel, P. G. [translated by E. E. Henty]. 1984. Flora of the Bismarck Archipelago for naturalists. Office of Forests, Division of Botany, Lae, Papua New Guinea. 638 pp. ISBN 9980-66-000-7.

Smith, Albert C. 1981. Flora Vitiensis nova: a new flora of Fiji. National Tropical Botanical Garden, Lawai, Kauai, Hawaii. Volume 2. 810 pp.

Staples, George W./Herbst, Derral/Imada, Clyde T. 2000. Survey of invasive or potentially invasive cultivated plants in Hawai‘i. Bishop Museum Occasional Papers No. 65. 35 pp.

Staples, George W./Imada, Clyde T./Herbst, Derral R. 2002. New Hawaiian plant records for 2000. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 2000. Part 1: Articles. Bishop Museum Occasional Papers. 68:3-18.

Stone, Benjamin C. 1970. The flora of Guam. Micronesica 6:1-659.

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu. 1919 pp. (two volumes).

Waterhouse, D. F. 1993. The major arthropod pests and weeds of agriculture in Southeast Asia. The Australian Centre for International Agricultural Research, Canberra. 141 pp.

Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. 1988. Flora of New Zealand, Volume IV: Naturalised pteridophytes, gymnosperms, dicotyledons. Botany Division, DSIR, Christchurch. 1365 pp.

Wu, Te-lin. 2001. Check List of Hong Kong Plants. Hong Kong Herbarium and the South China Institute of Botany. Agriculture, Fisheries and Conservation Department Bulletin 1 (revised). 384 pp.

Zhengyi, Wu/Raven, Peter H./Deyuan, Hong. 2011. Flora of China (online resource).