Mentha aquatica L., Lamiaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  yes

Other Latin names:  Mentha citrata Ehrh.; Mentha palustris Mill.

Common name(s): [more details]

English: water mint

French: baume d'eau, menthe acuatique

Japanese: mensa akuatika, menta akuatika, numa hakka

Spanish: bergamota, hierba buena, mentha, sándalo de agua

Habit:  aquatic herb

Description:  "Plant subglabrous to pubescent, with strong pleasant (not spearmint-like) scent. Stems erect, to 90cm. Leaves ovate, broadly cuneate to subcordate at base, with rather shallow, rather blunt teeth, petiolate. Upper whorls in axils of small bracts, congested to form rounded head. Calyx tubular, with narrowly triangular to subulate  teeth, 3-4.5mm. Corolla lilac"  (Interactive Flora of NW Europe [website now apparently defunct; see info from WorldCat]).

"Water mint has red-purple, erect stems to 12 inches; the leaves are dark green, broadly elliptic to more or less rectangular, 1-1.75 inches long and 0.8-1.2 inches wide, with an often puckered and crisped surface and serrate margins"  (Staples & Herbst, 2005; p. 358).

Habitat/ecology:  "In Chile this species grows in the following environmental conditions:  Low altitude, interior valleys; coastal mountains, 500-2000 m; coastal areas, 0-500 m. The plant grows in water or it has its roots within a permanent water course, this corresponds to marshes, bogs, water courses, lake and river shores; humid areas, with almost constant rainfall, short dry periods are possible (generally not longer than 1 month). Fully exposed to the sun, level areas or slopes facing north; some shadow, some protection against direct sunlight, some shadow from vegetation, filtering about 20-40% of light"  (Chileflora).

Propagation:  Perhaps by seed.  Spreads aggressively by underground runners (Staples & Herbst, 2005; p. 358).

Native range:  Europe, Africa, western Asia; naturalized elsewhere (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (p. 555)
State of Hawaii Hawaiian Islands	O‘ahu Island		Bishop Museum (U.S.A. Hawaii. Honolulu.) (1991) (voucher ID: BISH 603017) Taxon name on voucher: Mentha aquatica L.

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
British Columbia (province of Canada) Province of British Columbia	Canada (British Columbia)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
Central America Central America (Pacific rim)	Guatemala (Republic of)	introduced cultivated	U.S. Dept. Agr., Agr. Res. Serv. (2013)
China China	China (People's Republic of)	introduced cultivated	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) As Mentha citrata Ehrh. [= Mentha aquatica var. citrata]. Beijing Shi, Hangzhou Shi, Nanjing Shi, and other cities.
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 188)
Mexico Mexico	Mexico (United Mexican States)	introduced cultivated	U.S. Dept. Agr., Agr. Res. Serv. (2013)
New Zealand New Zealand	New Zealand (country)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)	introduced	Belov, Michail (2013)
United States (west coast) United States (west coast states)	USA (Oregon)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (west coast) United States (west coast states)	USA (California)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (west coast) United States (west coast states)	USA (Washington)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Canada Canada	Canada	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (continental except west coast) United States (other states)	United States (other states)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)

Control:  If you know of control methods for Mentha aquatica, please let us know.