Nasturtium microphyllum Boenn. ex Rchb., Brassicaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Rorippa microphylla (Boenn. ex Rchb.) Hyl. ex Á. Löve & D. Löve

Common name(s): [more details]

English: narrow-fruited water cress, one-row watercress, one-row yellow cress

French: cresson à petites feuilles

Hawaiian: lēkō

Japanese: chisa, kawara-chisa

Mangarevan: maru

Habit:  herb

Description:  "Aquatic or semiaquatic, somewhat fleshy, glabrous perennial herbs; stems floating, prostrate, or ascending, rooting at the nodes, hollow, 1-6 dm long, usually 2-6 mm in diameter.  Leaves pinnately compound with (3-) 6-9 leaflets, these ovate to elliptic, 1.5-4 cm long, 0.5-2 cm wide, margins subentire to sinuate-dentate, the terminal one often larger than lateral ones.  Pedicels 11-20 mm long in fruit; petals white, ca. 4 mm long.  Siliques 1.6-2.5 cm long.  Seeds in 1 row per cell, with ca. 100 polygonal depressions on each face" (Wagner et al., 1999; p. 411).

Habitat/ecology:  In Hawai‘i, "naturalized in running water or seasonally wet areas" (Wagner et al., 1999; p. 411).

Propagation:  Seed, vegetatively

Native range:  "Native to western Europe, widely cultivated as a food plant and widely naturalized in many areas" (Wagner et al., 1999; p. 411).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
French Polynesia Gambier Islands	Mangareva (Gambier) Island	introduced cultivated	St. John, Harold (1988) (p. 14) Voucher cited: St. John 14862 (BISH) Persisting from cultivation.
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 411)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 411)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 411)
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive cultivated	Wysong, Michael/Hughes, Guy/Wood, K. R. (2007) (p. 3) Voucher cited: Wysong 557 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 411)

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	National Herbarium of New South Wales (2013) As Rorippa microphylla (Boenn. ex Rchb.) Hyl. Naturalised
Australia Australia (continental)	Australia (continental)	introduced invasive	National Herbarium of New South Wales (2013) As Rorippa microphylla (Boenn. ex Rchb.) Hyl. South Australia, Tasmania, Victoria Naturalised
British Columbia (province of Canada) Province of British Columbia	Canada (British Columbia)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Japan Japan	Japan	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 183)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 441) As Rorippa microphylla (Reichb.) Hylander. Streams, ditches and drains.
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized

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 invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
United States (continental except west coast) United States (other states)	United States (other states)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized

Control:  If you know of control methods for Nasturtium microphyllum, please let us know.