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	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		Bishop Museum (Honolulu) (1977) (voucher ID: BISH 581869) Taxon name on voucher: Lemna perpusilla
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
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	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.

Additional information:
Photos and additional information at University of Florida, Center for Aquatic and Invasive Plants.

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

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

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

References:

Bishop Museum (Honolulu). 1937. Voucher specimen #BISH 112547 (St.John, H. 18373).

Bishop Museum (Honolulu). 1968. Voucher specimen #BISH 34270 (Degener, O. 32000).

Bishop Museum (Honolulu). 1977. Voucher specimen #BISH 581869 (Stemmermann, R.L. 3109).

Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. 2009. A checklist of the total vascular plant flora of Singapore: native, naturalised and cultivated species. Raffles Museum of Biodiversity Research, National University of Singapore. 273 pp.

Fosberg, F. R. 1983. Natural history of Cousin Island. In: Sachet, M. H., D. R. Stoddart, and F. R. Fosberg. Floristics and ecology of Western Indian Ocean islands. Atoll Research Bulletin No. 273. Smithsonian Institution, Washington. 253 pp.

Fosberg, F. R./Falanruw, M. V. C. 1980. Noteworthy Micronesian plants 4. Micronesica 16(2):201-210.

Li-ying, Li/Ren, Wang/Waterhouse, D. F. 1997. The distribution and importance of arthropod pests and weeds of agriculture and forestry plantations in southern China. ACIAR, Canberra, Australia. 185 pp.

Parham, B. E. V. 1972. Plants of Samoa. New Zealand Dept. of Scientific and Industrial Research Information Series No. 85, Wellington. 162 pp.

Smith, Albert C. 1979. Flora Vitiensis nova: a new flora of Fiji. National Tropical Botanical Garden, Lawai, Kauai, Hawaii. Volume 1. 494 pp.

Space, James C./Flynn, Tim. 2001. Report to the Kingdom of Tonga on invasive plant species of environmental concern.  USDA Forest Service, Honolulu. 78 pp.

Swarbrick, J. T. 1997. Environmental weeds and exotic plants on Christmas Island, Indian Ocean: a report to Parks Australia. 101 pp. plus appendix.

U. S. Government. 2011. Integrated Taxonomic Information System (ITIS) (on-line resource).

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).

Waterhouse, D. F. 1993. The major arthropod pests and weeds of agriculture in Southeast Asia. The Australian Centre for International Agricultural Research, Canberra. 141 pp.

Whistler, W. A. 1992. Flora of Tonga [unpublished checklist]. 107 pp.

Wu, Te-lin. 2001. Check List of Hong Kong Plants. Hong Kong Herbarium and the South China Institute of Botany. Agriculture, Fisheries and Conservation Department Bulletin 1 (revised). 384 pp.

Yuncker, T. G. 1959. Plants of Tonga. Bishop Museum Bull. 220. Bishop Museum Press, Honolulu. 343 pp.

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