Ammannia auriculata Willd., Lythraceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

Chinese: er ji shui xian

English: eared redstem

Habit:  herb

Description:  "Slender annual 0.5-5(8) dm tall, simple or branched above the base, the branches ascending. Leaves linear-lanceolate to linear-oblong, 1-4(6.5) cm long, 1.5-6(10) mm wide, auriculate-clasping at the base. Inflorescences of simple to compound, rather open cymes, peduncled from the axils, with (1)3-12(15) flowers per axil, most with at least 7 flowers; peduncles filiform, 3-9 mm long; pedicels 1-3(6) mm long. Calyx tube 1-3 mm long in flower, the lobes alternating with short appendages or the appendages absent; petals 4, deep rose-purple, ca. 1.5 mm long; stamens 4(-8), anthers deep yellow when fresh; styles 1-3 mm long in fruit. Capsules 1.5-3 mm in diameter, equaling or exceeding the calyx" (Aquatic and Wetland Vascular Plants of the Northern Great Plains).

Habitat/ecology:  "Muddy shores, flats and low spots in fields where water stands temporarily" (Aquatic and Wetland Vascular Plants of the Northern Great Plains).

Propagation:  Seed

Native range:  Americas, Africa, Asia

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Philippines Philippine Islands	Philippine Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Philippines Philippine Islands	Philippine Islands		Merrill, Elmer D. (1923) (p. 135)
Solomon Islands Solomon Islands	Solomon Islands		Swarbrick, John T. (1997) (p. 88)
Solomon Islands Solomon Islands	Solomon Islands	native	Hancock, I. R./Henderson, C. P. (1988) (p. 46)

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	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Australia Australia (continental)	Queensland	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
China China	China (People's Republic of)		Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2011) Wet places, rice farms.
Colombia Colombia	Colombia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
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)
El Salvador El Salvador	El Salvador (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Guatemala Guatemala	Guatemala (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Honduras Honduras	Honduras (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Japan Japan	Japan (country)	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 186)
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)

Comments:  See p. 1884, Wagner et al., 1999. Misidentified and not present in Hawai‘i.

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

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

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

References:

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

Merrill, Elmer D. 1923. An enumeration of Philippine flowering plants, vol. 3 [reprint]. Bureau of Printing, Manila. 628 pp.

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.

Swarbrick, John T. 1997. Weeds of the Pacific Islands. Technical paper no. 209. South Pacific Commission, Noumea, New Caledonia. 124 pp.

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.

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).

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