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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: water spangles

Synonyms and Other Names: common salvinia, water fern

Salvinia auriculata auct. non Aubl., Salvinia rotundifolia auct. non Willd.

Taxonomy: available through www.itis.gov

Identification: According to Nauman 1993; Wunderlin 1998; Mickel and Beitel 1988; Stoltze 1983:

Habit: Free floating, rootless aquatic fern.

Stems/Roots: Horizontal, branching rhizomes float just below the water surface and produce, at each node, two floating to emergent leaves, and a third, submersed leaf that is dissected into filaments.

Leaves: Floating leaves are orbicular to oval in shape, with heart shaped bases and rounded to notched tips. Leaf length ranges from 0.4 to 2.0 cm. Smaller, orbicular leaves lie flat on the water surface; larger leaves become elongated and fold upright on the midrib. Shade grown leaves remain broadly orbicular, and emerald green. Leaves grown in full sun become larger and elongated and often change from emerald green to rusty brown with maturity and senescence. The upper surfaces of floating leaves are uniformly covered with rows of white, bristly hairs. The stalks of each hair divide into four thin branches that are spreading and free at the tips. The branching hairs create a water repellent shield. Long chestnut colored hair coats the underside of floating leaves, the submersed filaments, buds, and the rhizome.

Spores: Salvinia minima is believed to be a sterile species. It is not known to produce fertile spores and is postulated to be of hybrid origin (Schneller 1980). Regardless, sporocarps are common among the submersed leaves of large plants. Sporocarps are sacs, which enclose smaller sacs (sporangia) that are formed to hold microscopic spores. Shaped like small lemons (~1 mm wide) sporocarps are attached in spirals along the main axis of the submersed filaments.

Look-a-likes: Salvinia minima has hairs on the leaf which are free at the tips, unlike Salvinia molesta where the hairs resemble tiny “egg-beaters” (Julien et al. 2002).

Size: 0.4 to 2 centimeters in length

Native Range: Central and South America; common and wide-ranging from southern Mexico to northern Argentina and Brazil (Mickel and Beitel 1988, Stolze 1983). De la Sota (1976) remarked that, in Argentina, the natural range of Salvinia minima could not be precisely determined due to its frequency in the water garden and aquarium trade.

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology:

Life history: Salvinia minima has three separate growth stages. In the primary stage, a small number of fern buds are introduced to a new environment, where they lie flat on the surface of the water. As the ferns grow into their secondary stage, their leaves being begin to curl upwards when the plants crowd against each other as they spread, while in the final tertiary stage, the leaves can become almost vertical due to crowding as the plants form a mat covering the water surface (Tewari and Johnson 2011).

The continuous branching and fragmentation of rhizomes turns out large volumes of vegetative daughter plants throughout the growing season. Copious hairy coverings minimize the desiccation of plants spotted on boats, trailers, alligators, turtles, and even dogs leaving the water. Lateral buds deeply imbedded in the rhizome, may lie dormant during periods of reduced moisture and cold temperature. Small rhizome fragments, commonly sheltered in associating vegetation, provide material for reintroduction on the return of favorable growing conditions.

Habitat: Salvinia minima prefers shallow backwaters of bayous, lakes and ponds, oxbows, ditches, slow flowing streams, cypress swamps, and marshes (Lellinger 1985, Nauman 1993, Jacono et al. 2001). Like Salvinia molesta, S. minima is vulnerable to conditions of salinity. Biologists along the coast of southeastern Texas find Salvinia minima in their coastal study sites only during wintertime, when freshwater outflow is high and salinity measurements decline to 4 – 7 ppt. They regularly control Salvinia minima, and improve waterfowl habitat, by opening gates to allow saline water from the Gulf of Mexico into the bayous (Kirk Blood, Texas Parks and Wildlife Department, Port Arthur, Texas, pers. comm.). During August, on the Waterhole Branch of the Fish River, Alabama, Salvinia minima was registered as growing well with surface water salinity levels at 4 –5 ppt. (Scott Phipps, Weeks Bay National Estuarine Research Reserve, AL, pers. comm.).

Means of Introduction: First reported in Florida in 1930, probably from ship ballast released into the Saint John River (Schmitz et al. 1998) and cultivated in greenhouses and gardens in the United States since the late 1880s (Weatherby 1921, 1937; Fernald 1950). Early plants in Florida likely entered natural areas from flooding of cultivated pools or through intentional release (Jacono et al 2001). Salvinia minima is still widely available in the water garden trade, either as a sale item or a contaminant. Secondary introductions are likely due to hitchhiking on animals and boats.

Status:

Established in: Alabama, Florida, Louisiana, Minnesota, New York, and Texas (GISD 2018).

Locally established in: Missouri, Mississippi

Collected in: Arkansas, Maine, Maryland, New Mexico, New York, Oklahoma

Impact of Introduction:

Summary of species impacts derived from literature review. Click on an icon to find out more...

Ecological	Economic

During earlier stages of colonization Salvinia minima demonstrates exponential growth rates (Gaudet, 1973), which may be just as high as those of Salvinia molesta. In Texas and Louisiana, S. minima typically occurs in dense, expansive populations and is known as a very troublesome weed. At Lacassine Bayou, southwestern Louisiana, plants completely blanket a waterway measuring 19.3 km long and 110 m wide (Jacono et al 2001). Mats in Louisiana have been measured as thick as 20 - 25 cm (Montz 1989).

Clatworthy and Harper (1962) studied the competition among three species of duckweed, Spirodela polyrrhiza, Lemna gibba, Lemna minor, and the single temperate species of Salvinia, S. natans. Salvinia natans outcompeted Spirodela polyrrhiza and Lemna minor in mixed culture, but a comparison of growth rates between mixtures of Salvinia minima and Spirodela polyrrhiza demonstrated that reduction or elimination of Salvinia minima through insect herbivory did not lead to any increase in Spirodela biomass (Tipping et al. 2009).

An eight-year study at Jean Lafitte National Historic Park, Louisiana, found complete displacement of native Lemna species by Salvinia minima. (T. Doyle, LA, pers. comm.), but a vegetation survey of the park conducted from May 2003 – August 2004 found that while S. minima was common in the waterways, Lemna minor was sporadically apparent in the floating mats (Nolfo-Clements 2006). The Lemnaceae (duckweeds) contain high protein content and are important food sources for waterfowl.

An investigation of competition among Salvinia minima, Spirodela [Landoltia] punctata (G.F.W. Mey.) C.H. Thompson and Azolla caroliniana Willdenow in north Florida found Salvinia minima dominating during the summer months (Dickinson and Miller 1998). Later in the season, S. minima was impacted by flooding and freezing and Spirodela punctata became the most abundant species (Dickinson and Miller 1998). Also introduced to North America, Spirodela punctata shows greater cold tolerance than Salvinia minima by extending to more northern temperate latitudes (Landolt 1986).

Remarks: Genetic studies indicate that S. minima was introduced in the east and has spread westward throughout the United States (Madeira et al. 2003, Rowe et al. 2018). While it is a pest species in Louisiana and Texas, insect herbivory, large fluctuations in water depth and competition with other floating plant species tends to suppress S. minima in Florida (Tipping and Center 2005, Tipping et al. 2009 and 2013).

The salvinia weevil Cyrtobagous salviniae has been successfully used for biocontrol of Salvinia molesta in Australia, Papua New Guinea, Sri Lanka, India, Botswana and Namibia, suppresses the population of Salvinia minima in Florida and has been introduced into Louisiana and Texas beginning in 2001 (Room 1990, Room et al. 1981, Parys and Johnson 2013, Tipping and Center 2003 and 2005, Tipping et al. 2012a and 2012b). At Jean Lafitte National Historic Park in Louisiana the salvinia weevil was negatively impacted by the red imported fire ant Solenopsis invicta, hampering biocontrol of Salvinia minima (Parys and Johnson 2012 and 2013).

The native salvinia stem-borer moth Samea multiplicalis has been shown to reduce S. minima biomass, especially in conjunction with C. salviniae in south Louisiana (Tewari and Johnson 2011). The waterfern weevil (Stenopelmus rufinasus) will feed on Salvinia minima, but only when its preferred host plant is depleted (Parys et al. 2015).

References: (click for full references)

Clatworthy, J.N. and J.L. Harper. 1962. Comparative biology of closely related species living in same area. 5. Inter- and intraspecific interference within cultures of Lemna spp. and Salvinia natans, J. Exp. Bot. 13:307–324.

Cozad, A,R.; Diaz, R; and C. Mudge., C (2019). "Phenotypic plasticity in the cold tolerance of three populations of the salvinia weevil (Cyrtobagous salviniae) from Louisiana, USA". Biocontrol Science and Technology. 29 (9): 912–916. doi:10.1080/09583157.2019.1608512. S2CID 146039108

de la Sota, E.S. 1976. Sinopsis de las especies Argentinas del genero Salvinia Adanson (Salviniaceae - Pteridophyta). (Synopsis of the Argentine species of the fern-genus Salvinia Adanson (Salviniaceae).) Bol. Soc. Argent. Bot. 17. (1-2): 47 - 50.

Dickinson, M. B. & Miller, T. E. 1998. Competition among small, free-floating, aquatic plants. American Midland Naturalist, 140, 55–67.

Fernald, M.L., 1950. Gray’s Manual of Botany a handbook of the flowering plants and ferns of the central and northeastern United States and adjacent Canada. 8th (Centennial) ed. American Book Company, New York.

Flowgrow Aquatic Plant Database. 2021. “Salvinia minima – Common Salvinia”. http://www.flowgrow.de/db/aquaticplants/salvinia-minima

Gaudet, J. J. (1973). Growth of a floating aquatic weed, Salvinia under standard conditions. Hydrobiologia 4:77-106.

Global Invasive Species Database. 2021. Species profile: Salvinia minima. Edited 4 Oct 2010. http://issg.org/database/species/ecology.asp?si=570&fr=1&sts=sss&lang=EN

Haynes, R.R. and Jacono, C.C., 2000. Status of Salvinia (Salviniaceae) in Alabama. Castanea 65:225–227.

Jacono, C.C., Davern, T.R. and Center, T.D., 2001. The adventive status of Salvinia minima and S. molesta in the southern United States and the related distribution of the weevil Cyrtobagous salviniae. Castanea 66 (3):214–226.

Julien, M.H., T.D. Center, and P.W. Tipping. 2002. Floating fern (Salvinia). Pages 17-32 in Van Driesche, R., S. Lyon, B. Blossey, M. Hoddle, and R. Reardon, eds. Biological control of invasive plants in the eastern United States. USDA Forest Service Publication FHTET-2002-04. USDA Forest Service. Morgantown, WV.

Landolt, E. 1986. The family of Lemnaceae - a monographic study. Vol.1. In: Biosystematic investigations in the family of duckweeds (Lemnaceae). 2(71) :566.

Landry, G.P., 1981. Salvinia minima new to Louisiana. Amer. Fern J. 68:95.

Lawalree, A. 1964. Salviniaceae in Flora Europaea, vol. 1. In: Tutin, T.G. (Ed.), others with the assistance of P.W. Ball and A.O. Chater. University Press, Cambridge, pp. 24–25.

Lellinger, D.B. 1985. A Field Manual of the Ferns and Fern-Allies of the United States and Canada. Smithsonian Institute Press, Washington, DC.

Maki, K., and S. Galatowitsch. 2004. Movement of invasive aquatic plants into Minnesota (USA) through horticultural trade. Biological Conservation 118(3):389–396.

Madeira, P.T., C.C. Jacono, P. Tipping, T.K. Van, and T.D. Center. 2003. A genetic survey of Salvinia minima in the southern United States. Aquatic Botany 76(2):127-139.

Mickel J.T. and Beitel J.M. 1988. Pteridophyte flora of Oaxaca, Mexico. ((Memoirs of the New York Botanical Garden, 46)). Bronx: New York Botanical Garden 568p.

Montz, G. N. 1989. Distribution of Salvinia minima in Louisiana. In Proc. 23rd Annual Meeting, Aquatic Plt Control Res Prog., 14-17 November 1988, West Palm Beach, FL, Misc. Paper A-89-1, USACOE, Waterways Experiment Station, Vicksburg, MS.:312-316.

Natural Science Association of Staten Island. 1893. Salvinia natans on Staten Island. Pages 1-3 in Proceedings of the Natural Science Association of Staten Island, October 14, 1893.

Nauman C. E. 1993. Salviniaceae. Pp. 336–337, in Flora North America Editorial Committee. Flora of North America vol. 2. Pteridophytes and Gymnosperms. Oxford University Press, Oxford.

Nolfo-Clements, L.E. 2006. Vegetative survey of Wetland Habitats at Jean Lafitte National Historical Park and Preserve in Southeastern Louisiana. Southeastern Naturalist 5(3):499-514.

Parys, K.A., and S.J. Johnson. 2012. Impact of the Red Imported Fire Ant, Solenopsis invicta (Hymenoptera: Formicidae), on Biological Control of Salvinia minima (Hydropteridales: Salviniaceae) by Cyrtobagous salviniae (Coleoptera: Curculionidae). Florida Entomologist 95(1):136-142.

Parys, K.A., and S.J. Johnson. 2013. Biological Control of Common Salvinia (Salvinia minima) in Louisiana using Cyrtobagous salviniae (Coleoptera: Curculionidae). Florida Entomologist 96(1):10-18.

Parys, K.A., S. Tewari, and S.J. Johnson. 2015. Adults of the Waterfern Weevil, Stenopelmus rufinasus Gyllenhal (Coleoptera: Curculionidae), Feed on a Non-Host Plant, Salvinia minima Baker, in Louisiana. The Coleopterists Bulletin 69(2):316-318.

Proctor, G.R., 1989. Ferns of Puerto Rico and the Virgin Islands. Memoirs of the New York Botanical Garden, vol. 53. Bronx, New York.

Roalson, E.H., and K.W. Allred (eds.). 1995. A working index of New Mexico vascular plant names, plus supplements.

Room, P.M. 1990. Ecology of a simple plant-herbivore system: biological control of salvinia. Tree 5(3):74-79.

Room, P.M., K.L.S. Harley, I.W. Forno, and D.P.A. Sands. 1981. Successful biological control of the floating weed salvinia. Nature 294:78-80.

Rowe, C.A., D.P. Hauber, and P.G. Wolf. 2018. Genomic variation of introduced Salvinia minima in southeastern United States. Aquatic Botany 151:38-42.

Schneller J.J. 1980. Cytotaxonomic investigations of Salvinia herzogii de la Sota. Aquatic Bot. 9. (3): 279 - 283.

Small, J.K., 1931. Ferns of Florida: being descriptions of and notes on the fern-plants growing naturally in Florida (Illustrated). The Science Press, New York.

Sorrie, B.A., B. Connolly, B. Sorrie, and P. Somers. 2011. The Vascular Plants of Massachusetts: A County Checklist. MA Natural Heritage & Endangered Species Program, MA Div. of Fisheries and Wildlife, Westborough.

Stoltze, R.G., 1983. Ferns and fern allies of Guatemala. Part III. Marsileaceae, Salviniaceae, and the fern allies. Fieldiana Bot. 12:10–13.

Taylor, R.J., and C.E.S. Taylor. 1989. An annotated list of the ferns, fern allies, gymnosperms and flowering plants of Oklahoma.

Tewari, S., and S. Johnson. 2011. Impact of two herbivores, Samea multiplicalis (Lepidoptera: Crambidae) and Cyrtobagous salviniae (Coleoptera: Curculionidae), on Salvinia minima in south Louisiana. Journal of Aquatic Plant Management 49: 36-43.

Texas A&M AgriLife Extension. 2020. Common salvinia management options. Wildlife and Fisheries Sciences. http://aquaplant.tamu.edu/management-options/common-salvinia/

Tipping, P.W., and T.D. Center. 2003. Cyrtobagous salviniae (Coleoptera: Curculionidae) successfully overwinters in Texas and Louisiana. The Florida Entomologist 86(1):92-93.

Tipping, P.W., and T.D. Center. 2005. Population Dynamics of Cyrtobagous salviniae on Common Salvinia in South Florida. Journal of Aquatic Plant Management 43:47-50. http://www.apms.org/japm/vol43/v43p47.pdf.

Tipping, P.W., L. Bauer, M.R. Martin, and T.D. Center. 2009. Competition between Salvinia minima and Spirodela polyrhiza mediated by nutrient levels and herbivory. Aquatic Botany 90(3):231-234.

Tipping, P.W., M.R. Martin, and T.D. Center. 2012a. Weevils Versus No Weevils: A Comparison of Salvinia minima Populations in Florida and Louisiana. Florida Entomologist 95(3):779-782.

Tipping, P.W., M.R. Martin, L. Bauer, R.M. Pierce, and T.D. Center. 2012b. Ecology of common salvinia, Salvinia minima Baker, in southern Florida. Aquatic Botany 102:23-27.

Tipping, P.W., M.R. Martin, W.J. Hulslander Jr., P.T. Madeira, R.M. Pierce, M.D. Smart, and T.D. Center. 2013. Release and evaluation of Cyrtobagous salviniae on common salvinia in southern Louisiana. Journal of Aquatic Plant Management 51:34-38. http://www.apms.org/japm/vol51/japm-51-01-34.pdf.

Weatherby, C.A., 1921. Other records of Salvinia natans in the United States. Am. Fern J. 11 (2):50–53.

Weatherby, C.A., 1937. A further note on Salvinia. Am. Fern J. 27:98–102.

Wunderlin, R.P. 1998. Guide to the Vascular Plants of Florida. University Press of Florida. Gainesville, FL, 806 p.

Zolczynski, J., and Eubanks, M.J., 1990, Mobile delta submerged aquatic vegetation survey 1987: Mobile, Alabama Department of Conservation and Natural Resources and U.S. Army Corps of Engineers, Mobile District, 32 p.

Other Resources:
https://aquaplant.tamu.edu/plant-identification/alphabetical-index/common-salvinia/

https://assessment.ifas.ufl.edu/assessments/salvinia-minima/

Author: Howard Morgan, V., E. Anemaet, and E. Lower

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.