Cabomba caroliniana A.Gray, Cabombaceae

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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results: 

Australia:  Reject, score: 18 (Go to the risk assessment)
Risk assessment from the Government of Queensland, Australia (PDF format).

Common name(s): [more details]

Chinese: zhu jie shui song

English: cabomba, Carolina fanwort, Carolina water-shield, fanwort, fish-grass, Washington plant, Washington-grass

Habit:  herb

Description:  "Stems to 1-2 m, basally rhizomatous and glabrescent, apically rust colored pubescent. Submersed leaves petiole 0.3-1.5 cm; blade palmately dissected, 2-5 x 2.5-7 cm in overall diam., ultimate segments linear to slightly spatulate, to 1.8 mm wide. Floating leaves petiole 1.5-2 cm; blade 1.4-2 x ca. 0.3 cm. Flowers 0.6-1.5 cm in diameter. Sepals white, with margin tinged purple, or yellow, rarely purplish, 5-12 x 2-7 mm, apex obtuse. Petals colored as sepals, 4-12 x 2-5 mm, base clawed, apex broadly obtuse or emarginate; basal nectiferous auricles yellow. Stamens (3-)6, ca. 3.5 mm. Pistils (2-)3, 3.5-4 mm, short pubescent. Fruit 4-7 mm. Seeds 1-3, 1.5-3 x 1-1.5 mm"  (Flora of China online).

"Stems slender, coated with gelatinous matter, branching. Leaves petioled, peltate, the floating ones small, entire; submerged ones opposite, palmately dissected into numerous capillary segments. Flowers small, white or yellow. Sepals and petals 3. Stamens 3-6; filaments slender; anthers extrorse. Carpels 2-4. Stigmas small, terminal; ovules commonly 3, pendulous. Fruit coriaceous, indehiscent, about 3-seeded" (Britton & Brown, 1913; p. 76).

Habitat/ecology:  "Grows in humid, sub-humid and temperate regions where it requires direct sunlight and still water.  Favours nutrient-rich waterways including ponds, lakes and slow-moving streams. Out-competes native plants and presumably has a negative impact on native fish or aquatic invertebrates." (Smith, 2002; 81).

"Cabomba grows well on a silty bed but not so well on hard surfaces. It grows quickly - growth of 50 mm a day has been reported in Lake Macdonald in Queensland - allowing it to respond to wide fluctuations in water depth. It grows well in high nutrient environments with low pH, but in more alkaline waters it tends to lose its leaves. High calcium levels also inhibit growth. Unlike other aquatic weeds, cabomba can grow well in turbid water. It prefers a warm, humid climate with a temperature range of 13-27° C but can survive when the surface of the water body is frozen"  (Australian Weed Management Guide).

Propagation:  "Reproduction is mainly by fragmentation and dispersal by stem fragments of discarded aquarium plants" (Smith, 2002; 81).

Native range:  North and South America.

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	MacKee, H. S. (1994) (p. 25) Voucher cited: Veillon 1140 (NOU)

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)	Northern Territory	introduced invasive	Smith, Nicholas M. (2002) (p. 81) Infestaiton in Palmerston, N.T. under management.
Australia Australia (continental)	Queensland	introduced invasive	Smith, Nicholas M. (2002) (p. 81) Established in coastal rivers.
Canada Canada	Canada (country)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
China China	China (People's Republic of)	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2011) "In rivers".
Japan Japan	Japan (country)	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 182)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
United States (continental except west coast) United States (other states)	United States (other states)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)

Comments:  A "weed of national significance" in Australia; declared a noxious weed in Queensland, Northern Territory and Western Australia (Smith, 2002; 81).

Control: 

Physical:  "Physical cutting and removal is suited to accessible areas of closed water bodies with established heavy infestations. However, cabomba grows so quickly that treatment by this method is only likely to maintain a clear water surface for a few weeks. The cost of mechanically removing cabomba from dams is very high.  Operators and their equipment require rigorous hygiene protocols to minimise spread. The removal of plant material needs to be carefully controlled. Cabomba easily fragments from disturbance, so control activities can actually contribute to spread of the weed if great care is not taken"  (Australian Weed Management Guide).

Chemical:  "Chemical control is difficult because of the problems associated with applying chemicals in water and the potential to affect non-target species. However, there are cases where herbicides have been used successfully"  (Australian Weed Management Guide).

Additional information:
Information from the Washington State Department of Ecology.
Information from the Global Invasive Species Database.
Weed Management Guide from the Government of Australia. (PDF format).

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

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

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

References:

Britton, N.L. and A. Brown. 1913. An illustrated flora of the northern United States, Canada, and the British possessions, second edition, vol. 2. New York, Scribners.

MacKee, H. S. 1994. Catalogue des plantes introduites et cultivées en Nouvelle-Calédonie. Muséum National d'Histoire Naturelle, Paris, 164 p.

Mito, Toshikazu/Uesugi, Tetsuro. 2004. Invasive alien species in Japan: the status quo and the new regulation for prevention of their adverse effects. Global Environmental Research 8(2)/2004: 171-191.

Smith, Nicholas M. 2002. Weeds of the wet/dry tropics of Australia - a field guide. Environment Centre NT, Inc. 112 pp.

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

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