Mentha aquatica L., Lamiaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  yes

Other Latin names:  Mentha palustris Mill.

Common name(s): [more details]

English: water mint

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).

"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
Canada Province of British Columbia	Canada (British Columbia)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
Canada Canada	Canada (country)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
Chile (continental) Chile	Chile (Republic of)	introduced	Belov, Michail (2011)
Japan Japan	Japan (country)	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 188)
United States (west coast) United States (west coast states)	USA (Oregon)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
United States (west coast) United States (west coast states)	USA (California)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
United States (west coast) United States (west coast states)	USA (Washington)	introduced	U.S. Dept. Agr., Nat. Res. Cons. 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)

Additional information:
Photos and other information from Chileflora.

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

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

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

References:

Atkinson, Rachel/Sawyer, John. 2011. Naturalized species in the Juan Fernández Archipelago, Chile. Unpublished spreadsheet.

Belov, Michail. 2011. Chileflora (online resource).

Bishop Museum (U.S.A. Hawaii. Honolulu.). 1991. Voucher specimen #BISH603017(Mayeda, C.S. 32).

Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido. 2006. Nouveau catalogue de la flore vaculaire de l'archipel Juan Fernández (Chile) [Nuevo catálogo de la flora vacular del Archipélago Juan Fernández (Chile)]. Acta Bot. Gallica 153(4):399-587.

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.

Staples, George W./Herbst, Derral R. 2005. A tropical garden flora: plants cultivated in the Hawaiian Islands and other tropical places. Bishop Museum Press, Honolulu. 908 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.