Lemna spp. Araceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

Chinese: fu ping shu

English: duckweed

Habit:  aquatic herb

Description:  "Fronds free-floating on or just beneath water surface, solitary or cohering in colonies, usually greenish or purplish to reddish on lower surface, obovate to orbicular or greatly elongated, each one with a single peltately attached root. Flowers 3, borne in a pouch, 2 staminate and 1 pistillate, enclosed in a membranous sheath in a marginal cleft of the frond, opening along the side or nearly closed; ovules 1-3. Seeds 1-6, usually ribbed and with minute transverse striations" (Wagner et al., 1999; pp. 1457-1458, 1902).

Habitat/ecology:  Freshwater lakes, ponds, ditches, canals, and slow-moving streams.

Propagation:  Seed, pieces moved by water.

Native range:  Various

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Tinian Island		Wagner, W. L./ Herbst, D. R./Weitzman, A./Lorence, D.H. (2013) Lemna perpusilla Torr.
Commonwealth of the Northern Mariana Islands (US) Saipan	Saipan Island		Fosberg, F. R./Falanruw, M. V. C. (1980) (p. 203) Lemna purpusilla; voucher cited: P. Moore 911 (US)
Federated States of Micronesia Chuuk Islands	Weno (Moen) Island		Wagner, W. L./ Herbst, D. R./Weitzman, A./Lorence, D.H. (2013) Lemna perpusilla Torr.
Federated States of Micronesia Chuuk Islands	Weno (Moen) Island		Bishop Museum (Honolulu) (1977) (voucher ID: BISH 581869) Taxon name on voucher: Lemna perpusilla
Federated States of Micronesia Yap Islands	Yap (Waqab) Island		Wagner, W. L./ Herbst, D. R./Weitzman, A./Lorence, D.H. (2013) Lemna perpusilla Torr.
Fiji Fiji Islands	Viti Levu Island		Bishop Museum (Honolulu) (1968) (voucher ID: BISH 34270) Taxon name on voucher: Lemna perpusilla
Fiji Fiji Islands	Viti Levu Island		Bishop Museum (Honolulu) (1937) (voucher ID: BISH 112547) Taxon name on voucher: Lemna perpusilla
Guam Guam Island	Guam Island		Wagner, W. L./ Herbst, D. R./Weitzman, A./Lorence, D.H. (2013) Lemna perpusilla Torr.
Philippines Philippine Islands	Philippine Islands		Waterhouse, D. F. (1993) (pp. 66, 77) Lemna purpusilla
Samoa Western Samoa Islands	Upolu Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1989) (voucher ID: PTBG 3946) Taxon name on voucher: Lemna perpusilla Torrey
Samoa Western Samoa Islands	Western Samoa Islands		Parham, B. E. V. (1972)
Tonga Ha‘apai Group	Ha‘apai Islands	native	Whistler, W. A. (1992) (p. 88) Lemna perpusilla Torrey. Voucher cited: Buelow 384
Tonga Ha‘apai Group	Lifuka and Foa Islands	native	Space, James C./Flynn, Tim (2001) (p. Field notes.)
Tonga Tongatapu Group	Tongatapu Island	native	Whistler, W. A. (1992) (p. 88) Lemna perpusilla Torrey. Vouchers cited: Hurlimann 324, Buelow 243, Whistler 7502
Tonga Tongatapu Group	Tongatapu Island		Yuncker, T. G. (1959) (p. 76) Lemna minor L. Voucher cited: Hürlmann 324
Tonga Vava‘u Group	Vava‘u Island	native	Space, James C./Flynn, Tim (2001) (p. Field notes.)
Tonga Vava‘u Group	Vava‘u Island	native	Whistler, W. A. (1992) (p. 88) Lemna perpusilla Torrey. Voucher cited: Buelow 1044

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Cambodia Cambodia	Cambodia (Kingdom of)		Waterhouse, D. F. (1993) (pp. 66, 77) Lemna purpusilla
China China	China (People's Republic of)		Li-ying, Li/Ren, Wang/Waterhouse, D. F. (1997) (p. 173) Lemna purpusilla
China China	Hong Kong	native	Wu, Te-lin (2001) (p. 301) Lemna minor L. In ponds and paddy fields.
Indonesia Indonesia	Indonesia (Republic of)		Waterhouse, D. F. (1993) (pp. 66, 77) Lemna purpusilla
Malaysia Malaysia	Malaysia (country of)		Waterhouse, D. F. (1993) (pp. 66, 77) Lemna purpusilla
Negara Brunei Darussalam Brunei	Brunei (Negara Brunei Darussalam)		Waterhouse, D. F. (1993) (pp. 66, 77) Lemna purpusilla
Singapore Singapore	Singapore (Republic of)	introduced invasive	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 54) Lemna perpusilla Torr., naturalised
Taiwan Taiwan Island	Taiwan Island		Li-ying, Li/Ren, Wang/Waterhouse, D. F. (1997) (p. 173) Lemna purpusilla
Thailand Thailand	Thailand (Kingdom of)		Waterhouse, D. F. (1993) (pp. 66, 77) Lemna purpusilla
Vietnam Vietnam	Vietnam (Socialist Republic of)		Waterhouse, D. F. (1993) (pp. 66, 77) Lemna purpusilla

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia (Indian Ocean offshore islands) Christmas Island Group	Christmas Island	introduced cultivated	Swarbrick, J. T. (1997) (p. 118)
Seychelles Seychelles Islands	Cousin Island	native	Fosberg, F. R. (1983) (p. 33)

Comments:  Non-native species would be aquatic threats. Only one species, Lemna aequinoctialis [=perpusilla] Welwitsh, is native to the Pacific. It is recorded from at least Saipan, Tinian, Guam, Yap, Chuuk and Fiji. It is also present in Hawai‘i, but Wagner et al. (1999; pp. 1457-1458) say that it is not known whether it is native or naturalized.

Yuncker (1959; p. 76) reports L. minor on Tongatapu. Lemna sp. observed covering a pond on Vava‘u (Space & Flynn, 2001). Smith (1979; p. 461) reports L. aequinoctialis [=perpusilla] present in Tonga.

Parham (1972; p. 29) reports L. minor present in Samoa.

Control:  If you know of control methods for Lemna spp., please let us know.