Hydrocotyle ranunculoides L. f., Araliaceae

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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Common name(s): [more details]

English: water pennywort

Habit:  herb

Description:  "Plants entirely glabrous, the stems fleshy, floating in water or creeping. Leaves non-peltate, suborbicular to reniform and frequently broader than long, 0.5-8 cm in diameter, shallowly to rather deeply 3-7-lobed, the lobes rounded, crenate or lobulate, subequal. Petioles 1-35 cm long. Peduncles much shorter than the leaves, 0.5-6 cm long. Umbels 3-8-flowered, the petals greenish-white. Involucral bracts oval to orbicular, up to 1 mm long. Styles much shorter than fruit width, spreading, the stylopodium depressed. Pedicels 1-3 mm long, spreading. Fruit suborbicular to transversely elliptical, moderately flattened, 1.5-2.5 mm long, 2-3 mm broad, often maculate, the ribs filiform or obscure" (Mathias & Constance, 1976; p. 22).

Habitat/ecology:  Aquatic. "Dense growth can smother static or slowly flowing waterways, particularly in nutrient-rick waters" (Csurhes & Edwards, 1998).  "Naturalized populations exist in coastal, freshwater streams of Western Australia, where it is reported to have escaped from ornamental garden ponds" (Keighery, 1994, cited in Csurhes & Edwards, 1998; p. 167).

Propagation:  Rooting at nodes, stem fragments, seed.

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
Kiribati Line Islands	Teraina (Washington) Island	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)

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)	Australia (continental)	introduced invasive	Csurhes, S./Edwards, R. (1998) (p. 167) Western Australia; subject of an eradication program.
Canada Province of British Columbia	Canada (British Columbia)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Chile (continental) Chile	Chile (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Colombia Colombia	Colombia (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 186)
Costa Rica Costa Rica	Costa Rica (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Ecuador (Mainland) Ecuador	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Guatemala Guatemala	Guatemala (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Nicaragua Nicaragua	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Panama Panama	Panama (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Perú Perú	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
United States (west coast) United States (west coast states)	USA (Oregon)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
United States (west coast) United States (west coast states)	USA (California)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)

Additional information:
Photos and other information from Chileflora.

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

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

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

References:

Csurhes, S./Edwards, R. 1998. Potential environmental weeds in Australia: Candidate species for preventative control. Canberra, Australia. Biodiversity Group, Environment Australia. 208 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.

Mathias, M. E./Constance, L. 1976. 145. Umbelliferae. In: G. Harling & B. Sarre, eds. Flora of Ecuador, vol. 5.

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