Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Other Latin names:  Ammannia rotundifolia Buch.-Ham. ex Roxb.

Common name(s): [more details]

English: dwarf rotala, rotala, roundleaf toothcup

Habit:  aquatic herb

Description:  "Perennial or annual herb.  Stems usually branched, erect, floating or creeping, to 30 cm long.  Leaves decussate, sessile or shortly petiolate, broadly elliptic to orbicular, to 1.2 cm long.  Bracts ovate, obtuse, sometimes apiculate, the base obtuse; inflorescence bract to 4 mm long; flower bract to 2 mm long; bracteoles lanceolate, usually less than or equal to hypanthium length.  Flowers subsessile, in distinct many-flowered racemes.  Hypanthium campanulate, to 1 mm long; appendages absent.  Sepals 4, triangular, to 1 mm long.  Petals 4, obovate, 2-3 times a s long as sepals, mauve.  Stamens 4, inserted near base of hypanthium. Style to 0.5 mm long.  Capsule globose, c. 1.5 mm diameter, opening by 4 valves" (Orchard, 1990; p. 96).

"A perennial herb with slender prostrate rhizome and erect, glabrous stems 10-20 cm long.  The small, solitary flowers are borne in the axils of the small leaves.  Leaves are sessile, elliptic and opposite on the stem."  (Csurhes & Edwards, 1998; p. 55).

Habitat/ecology:  "The plant inhabits wetland areas, low-lying fields and moist soil adjacent to ponds and dams.  It is cultivated in outdoor ornamental ponds in tropical regions." (Csurhes & Edwards, 1998; p. 55).  "Grows in damp areas or submerged in water" (Orchard, 1990; p. 96).

Propagation:  Seed, stem fragments.

Native range:  Myanmar, Vietnam (GRIN).  "Occurs in S and SE Asia from India to Japan" (Orchard, 1990; p. 96).

Presence:

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)	New South Wales	introduced invasive cultivated	Csurhes, S./Edwards, R. (1998) (pp. 55-56) Naturalized.
Australia Australia (continental)	Queensland	introduced invasive cultivated	Csurhes, S./Edwards, R. (1998) (pp. 55-56) Naturalized.
China China	Hong Kong	native	Wu, Te-lin (2001) (p. 160) In paddy fields and wet places.
Taiwan Taiwan	Taiwan Island		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 311)
Vietnam Vietnam	Vietnam (Socialist Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)

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)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011) Alabama
United States (continental except west coast) United States (other states)	USA (Florida)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)

Comments:  "The plant is widely used by aquarists and sold through the pet industry" (Csurhes & Edwards, 1998; p. 55).

Additional information:
Additional online information about Rotala rotundifolia is available from the Hawaiian Ecosystems at Risk project (HEAR).

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

Taxonomic information about Rotala rotundifolia 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.

Orchard, A. E., ed. 1990. Flora of Australia. Vol. 18, Podostemaceae to Combretaceae. Australian Government Publishing Service, Canberra.

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

U.S. Dept. Agr., Nat. Res. Cons. Serv. 2011. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

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.