Pacific Island Ecosystems at Risk (PIER)

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Salvinia molesta
D.S.Mitchell, Salviniaceae
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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results: 

Reject, score: 19 (Go to the risk assessment (Australia))
High risk, score: 29 (Go to the risk assessment (Pacific))

Other Latin names:  Salvinia auriculata Aubl.

Common name(s): [more details]

English: African payal, aquarium water-moss, giant salvinia, kariba weed, salvinia, water fern

French: salvinia

Habit:  aquatic fern

Description:  "A free-floating, rapid-growing, mat-forming, branched, gregarious, annual or perennial fern; individual plants up to 30 cm long with numerous leaves which usually form a mat to 2.5 cm thick, although they can form very dense mats also; slender horizontal floating rhizome producing at each node two short petioled or sessile fronds on the upper side and a long filiform feathered rootlike frond downward; leaves (fronds) produced in groups of three, from the delicate stem, each group with two broadly ovate, entire, undivided, green, aerial leaves up to 25 mm long situated on the upper side of the stem, with a distinct midrib from the base to the apex, the upper surface covered with close parallel rows of numerous long hairs that terminate in a cagelike, club-shaped tip and that prevent the leaves from getting wet, lower leaf surfaces smooth except for simple hairs (rootlets?) near the midrib; the leaves of young plants on open water float flat on the surface, later with age and crowding they fold against one another with the hairy upper surfaces  facing each other; the third, the submerged, rootlike "water" leaf, situated ventrally, is much divided, feathery, brown, up to 25 cm long, resembles and functions as a true root, and bears the sporocarp or spore-forming structures; sporocarps globose 2 to 3 mm in diameter, on a short stalk 1 mm long, densely hairy, indehiscent, monoecious, seated in clusters on the stem at the base of the rootlike, submerged leaves; megaspores and microspores about 2 mm long, numerous, globular, covered with minute hairs.  The presence of numerous, cagelike, clubshaped hairs on the upper surfaces of the aerial leaves is very distinctive.  This feature imparts an additional buoyancy to the plant and serves to distinguish S. [molesta] from any other species of the genus" (Holm et al., 1977; p. 409).

"Perennial, free-floating, aquatic fern, forming dense mats with plagiotropic shoots and tightly overlapping leaves.  Leaves:  Floating leaves of different sizes, elliptic, entire, folded, light or brownish-green, becoming somewhat darker near the entire margins, densely covered on upper surface by hydrophobic papillae bearing groups of 2 or 4 uniseriate hairs united at their distal ends; papillae to 3 mm long; submerged leaf greatly dissected, hanging into the water, functioning as a root.  Sporocarps in long straight secund chains, hairy, about 1 mm in diameter, containing mostly empty sporangia"  (Cronk and Fuller, 1995; pp. 119-122).

See also Salvinia cucullata and Salvinia natans.

Habitat/ecology:  "This species grows best in stagnant or slow-flowing water and prefers the small bays of dissected shorelines and the estuaries of small streams.  Growing around emergent brush and trees on flooded shorelines it is protected from wave action and multiplies rapidly.  The optimum range of temperature for good growth is 25 to 28 C.  The plant can tolerate a wide pH range; the optimum is thought to be pH 6 to 7.5" (Holm et al., 1977; p. 411).

"Still or slowly moving fresh to slightly brackish waters in tropical, subtropical and warm temperate regions.  A serious weed of waterways and other wet areas" (Parsons and Cuthbertson, 1992; pp. 18-22). In New Caledonia, "cette fougère flottante est devenue depuis une vingtaine d'années abondante dans la Rivière de Koumac et dans certains se ses affluents. Plus récemment elle devient gênante dans le secteur Boulouparis-La Foa où elle couvre d'une couche dense, compacte et continue des retenues d'eau artificielles" (MacKee, 1994; p. 126); "Fougère flottante, devenue abondante depuis une vingtaine d'années dans la rivière de Koumac et dans certains de ses affluents. Plus récemment, elle devient gênante dans le secteur Boulouparis-La Foa où elle couvre d'une couche dense, compacte et continue des retenues d'eau artificielles (Gargominy et al., 1996; p. 383).

Propagation:  Reproduces vegetatively; dispersed by wind and water. "Reproduces only by vegetative pieces which are spread by floodwaters, boats, vehicles and animals.  Many infestations have arisen from discarded aquarium material." (Smith, 2002; p. 83).

Native range:  South America (southern Brazil).

Presence:

Pacific
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Fiji
Fiji Islands
Fiji Islands   Swarbrick, John T. (1997) (p. 96)
Fiji
Fiji Islands
Fiji Islands   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 320)
French Polynesia
French Polynesia Islands
French Polynesia Islands   Waterhouse, D. F. (1997) (p. 65)
French Polynesia
Society Islands
Tahiti Island introduced
invasive
Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013)
Adventice
State of Hawaii
Hawaiian Islands
Hawai‘i (Big) Island introduced
invasive
Wilson, Kenneth A. (2003) (pp. 6-7)
Vouchers cited: Shishido s.n. (BISH 657222), C. Hirayama & L. Nakahara s.n. (BISH 657220, LAM), C. Hirayama & L. Nakahara s.n. (BISH 657221, LAM)
State of Hawaii
Hawaiian Islands
O‘ahu Island introduced
invasive
Wilson, Kenneth A. (2003) (pp. 6-7)
Vouchers cited: K. Wilson & G. Staples s.n. (BISH 606163), W. Hoe 5351 (BISH), G. Staples 1137 (BISH), J. Cook s.n. (BISH 655219), Nakahara, Heu & Matayoshi 99-01 (BISH, LAM), C. Imada 99-12 (BISH, LAM), D.D. Palmer 3123 (BISH, LAM), M. Buck s.n. (BISH 655286, LAM), Staples & Ahsing 1185 (BISH 658380, LAM), Higashi s.n. (BISH 655127), F. Kraus s.n. (BISH 655218), G. Higashi et al. s.n. (BISH 657219, LAM)
New Caledonia
New Caledonia
New Caledonia Islands introduced
invasive
Meyer, Jean-Yves (2000) (p. 99)
"Rivers and wetlands"
New Caledonia
New Caledonia Archipelago
Île Grande Terre introduced
invasive
Gargominy, Oliver/Bouchet, Philipe/Pascal, Michel/Jaffre, Tanguy/Tourneu, Jean-Christophe (1996) (p. 383)
New Caledonia
New Caledonia Archipelago
Île Grande Terre introduced
invasive
cultivated
MacKee, H. S. (1994) (p. 126)
Vouchers cited: MacKee 4202, MacKee 14783, MacKee 24630, MacKee 25983, MacKee 45767, Suprin in MacKee 46013
Papua New Guinea
Papua New Guinea (eastern New Guinea Island)
Papua New Guinea (eastern New Guinea Island)   Waterhouse, D. F. (1997) (p. 65)
Vanuatu
New Hebrides Islands
Vanuatu (Republic of) introduced
invasive
Meyer, Jean-Yves (2000) (p. 106)
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
Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 412)
Australia
Australia (continental)
New South Wales introduced
invasive
Australian Biological Resources Study (2013)
Australia
Australia (continental)
Northern Territory introduced
invasive
Smith, Nicholas M. (2002) (p. 83)
Australia
Australia (continental)
Northern Territory introduced
invasive
Australian Biological Resources Study (2013)
Australia
Australia (continental)
Queensland introduced
invasive
Smith, Nicholas M. (2002) (p. 83)
Australia
Australia (continental)
Queensland introduced
invasive
Australian Biological Resources Study (2013)
Colombia
Colombia
Colombia (Republic of)   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 320)
Indonesia
Indonesia
Indonesia (Republic of) introduced
invasive
Cronk, Q. C. B./Fuller, J. L. (2001) (p. 120)
Japan
Japan
Japan (country) introduced
Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 181)
Malaysia
Malaysia
Malaysia (country of) introduced
invasive
Waterhouse, D. F. (1993) (pp. 68, 78)
New Zealand
New Zealand
New Zealand (country) introduced
invasive
Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 37)
"Lakes, ponds and dams with still or slow-moving water, swamps".
Singapore
Singapore
Singapore (Republic of) introduced
invasive
Cronk, Q. C. B./Fuller, J. L. (2001) (p. 120)
Singapore
Singapore
Singapore (Republic of) introduced
invasive
Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 77)
Naturalised
Indian Ocean
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
La Réunion (France)
La Réunion Island
La Réunion Island introduced
invasive
Comité français de l'Union Internationale pour la Conservation de la Nature en France (2013)
French Territory of Mayotte
Mayotte Islands
Mayotte Island introduced
invasive
Comité français de l'Union Internationale pour la Conservation de la Nature en France (2013)

Comments:  Two other species of Salvinia, S. cucullata Roxb.and S. natans (L.) All., are also pest species and are present in southeast Asia, Indonesia, and Papua New Guinea (Waterhouse and Mitchell, 1998; pp. 91-94).

A "weed of national significance in Australia; a declared noxious weed in Western Australia, the Northern Territory and Queensland" (Smith, 2002; p. 83).

Control:  See "Biology and control of aquatic plants: A best management practices handbook"  for control information (large file, PDF format).

Physical:  Large infestations may be mechanically harvested but this may cause fragmentation and further spread.

Chemical: "Herbicides used are diquat formulated for use in running waters, hexazinone, chlosulfuron, or fluridone"  (Weber, 2003; p. 384).  Also see Parsons and Cuthbertson (1992; pp. 18-22).

Biological: "Biological control is the most effective method of removing salvinia.  Spectacular results have been obtained in parts of Australia and it seems likely that they will be repeated elsewhere.  The initial control obtained in Lake Moondarra, following the release of the weevil, Cyrtobagous salviniae, in 1981, was so successful that it became counterproductive when the weevil died out after destroying the weed, allowing re-infestation to occur.  Further releases of the insect, however, quickly brought the weed under control once again.  Similar results have followed the release of the weevil in Papua New Guinea, India and Namibia but not in Kakadu National Park in the Northern Territory.  It has since been suggested that there is a critical population density of the weed, associated with high water temperatures, below which the weevil cannot survive.

"A pyralid moth, Samea multiplicalis, released at Lake Julius, Queensland, was not as effective as the weevil and did not control the weed.  Because of this, although both species are active in the temperature range of 16° to 30° C, causing more damage at the higher temperature, it is concluded that the weevil alone, or in combination with the moth, will readily control salvinia north of Brisbane but that the moth alone will not"  (Parsons and Cuthbertson, 1992; pp. 18-22).

Biological control information from the publication "Biological control of invasive plants in the eastern United States".

For a summary of other efforts, see Julien (1992; pp. 84-87, 136-137).

Additional information:
Information on the Environment Bay of Plenty, New Zealand, web site.
Information from the Global Invasive Species Database.
Information from the Bugwood Wiki.
Fact sheet from the Bay of Plenty Regional Council, New Zealand.
Fact sheet from the Government of Queensland, Australia (PDF format).
Photos and additional information at University of Florida, Center for Aquatic and Invasive Plants.
Weed Management Guide from the Government of Australia. (PDF format).
Information sheet from Weedbusters New Zealand.
See information in the book "Biology and control of aquatic plants: A best management practices handbook"  (large file, PDF format).
Article from "Wildland Weeds".

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

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

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

References:

Australian Biological Resources Study. 2013. Flora of Australia Online. Australian Biological Resources Study, Canberra.

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.

Comité français de l'Union Internationale pour la Conservation de la Nature en France. 2013. Les espéces envahissantes en outre-mer (online resource).

Cronk, Q. C. B./Fuller, J. L. 2001. Plant invaders. Earthscan Publications, Ltd., London. 241 pp.

Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. 2013. Base de données botaniques Nadeaud de l'Herbier de la Polynésie Française (PAP). (online resource).

Gargominy, Oliver/Bouchet, Philipe/Pascal, Michel/Jaffre, Tanguy/Tourneu, Jean-Christophe. 1996. Conséquences des introductions d'espèces animales et végétales sur la biodiversité en Nouvelle-Calédonie. Rev. Ecol. (Terre Vie) 51:375-401.

Gettys, Lyn A./Haller, William T./Bellaud, Marc; eds. 2009. Biology and control of aquatic plants: A best management practices handbook. Aquatic Ecosystem Restoration Foundation, Marietta, Georgia. ISBN 978-0-615-32646-7. 200 pp.

Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. 1977. The world’s worst weeds: distribution and biology. East-West Center/University Press of Hawaii. 609 pp.

Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. 1979. A geographical atlas of world weeds. John Wiley & Sons, New York. 391 pp.

Julien, M. H. (ed.). 1992. Biological control of weeds: A world catalogue of agents and their target weeds (third edition). CAB International, Wallingford, UK. 186 pp.

MacKee, H. S. 1994. Catalogue des plantes introduites et cultivées en Nouvelle-Calédonie. Muséum National d'Histoire Naturelle, Paris, 164 p.

Meyer, Jean-Yves. 2000. Preliminary review of the invasive plants in the Pacific islands (SPREP Member Countries). In: Sherley, G. (tech. ed.). Invasive species in the Pacific: A technical review and draft regional strategy. South Pacific Regional Environment Programme, Samoa. 190 pp.

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.

Owen, S. J. 1997. Ecological weeds on conservation land in New Zealand: A database. Working draft. Wellington, New Zealand. Department of Conservation.

Parsons, W. T./Cuthbertson, E. G. 1992. Noxious weeds of Australia. Inkata Press, Melbourne/Sydney. 692 pp.

Smith, Nicholas M. 2002. Weeds of the wet/dry tropics of Australia - a field guide. Environment Centre NT, Inc. 112 pp.

Staples, George W./Herbst, Derral/Imada, Clyde T. 2000. Survey of invasive or potentially invasive cultivated plants in Hawai‘i. Bishop Museum Occasional Papers No. 65. 35 pp.

Swarbrick, John T. 1997. Weeds of the Pacific Islands. Technical paper no. 209. South Pacific Commission, Noumea, New Caledonia. 124 pp.

U. S. Government. 2013. Integrated Taxonomic Information System (ITIS) (on-line resource).

U.S. Dept. Agr., Agr. Res. Serv. 2013. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Van Driesche, Roy/Lyon, Suzanne/Blossey, Bernd/Hoddle, Mark/Reardon, Richard. 2002. Biological control of invasive plants in the eastern United States. USDA Forest Service Publication FHTET-2002-04. 413 pp.

Waterhouse, B. M./Mitchell, A. A. 1998. Northern Australia Quarantine Strategy: weeds target list. Second edition. Australian Quarantine & Inspection Service, Miscellaneous Publication No. 6/98. 110 pp.

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.

Waterhouse, D. F. 1997. The major invertebrate pests and weeds of agriculture and plantation forestry in the Southern and Western Pacific. The Australian Centre for International Agricultural Research, Canberra. 93 pp.

Waterhouse, D. F./Norris, K. R. 1987. Biological control: Pacific prospects. Inkata Press, Melbourne. 454 pp.

Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. 1988. Flora of New Zealand, Volume IV: Naturalised pteridophytes, gymnosperms, dicotyledons. Botany Division, DSIR, Christchurch. 1365 pp.

Weber, Ewald. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK. 548 pp.

Wilson, Kenneth A. 2003. New records of alien pteridophytes for Hawai‘i. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 2001-2002. Part 2: Notes. Bishop Museum Occasional Papers. 74:5-7.


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This page was created on 1 JAN 1999 and was last updated on 22 AUG 2011.