Salvinia minima Baker

Common Name: Water spangles

Synonyms and Other Names:

Salvinia rotundifolia, common salvinia, floating fern, Salvinia auriculata auct. non Aubl., Salvinia rotundifolia auct. non Willd.




Alan Cressler, 2016 all rights reservedCopyright Info


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Identification: Free floating, rootless aquatic fern. Horizontal, branching rhizomes float just below the water surface and produce two floating to emergent leaves at each node, along with a third submersed leaf that is dissected into filaments. 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. These branching hairs create a water-repellent shield. Long chestnut-colored hairs coat the underside of floating leaves, the submersed filaments, buds, and the rhizome.

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 sac-shaped, and enclose smaller sacs (sporangia) that are formed to hold microscopic spores. Small (~1 mm wide) lemon-shaped sporocarps are attached in spirals along the main axis of the submersed filaments. For further details on identification, see Nauman 1993; Wunderlin 2000; Mickel and Beitel 1988; and Stoltze 1983.


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.


This species is not currently in the Great Lakes region but may be elsewhere in the US. See the point map for details.

Table 1. States/provinces with nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Salvinia minima are found here.

State/ProvinceFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AL1982201810Escatawpa; Lower Black Warrior; Lower Tallapoosa; Middle Chattahoochee-Walter F; Middle Tombigbee-Chickasaw; Mobile Bay; Mobile-Tensaw; Mulberry; Perdido; Upper Conecuh
AR199819992Bayou Meto; Lower Arkansas
CA200820095Aliso-San Onofre; Salton Sea; San Luis Rey-Escondido; Santa Ana; Whitewater River
FL191750Alafia; Alapaha; Apalachee Bay-St. Marks; Apalachicola; Apalachicola Bay; Aucilla; Big Cypress Swamp; Caloosahatchee; Cape Canaveral; Charlotte Harbor; Chipola; Crystal-Pithlachascotee; Daytona-St. Augustine; Econfina-Steinhatchee; Escambia; Everglades; Florida Southeast Coast; Hillsborough; Kissimmee; Lake Okeechobee; Little Manatee; Lower Chattahoochee; Lower Choctawhatchee; Lower Ochlockonee; Lower St. Johns; Lower Suwannee; Manatee; Myakka; Nassau; New; Northern Okeechobee Inflow; Oklawaha; Peace; Pensacola Bay; Perdido; Santa Fe; Sarasota Bay; South Atlantic-Gulf Region; Southern Florida; St. Andrew-St. Joseph Bays; St. Marys; Tampa Bay; Upper St. Johns; Upper Suwannee; Vero Beach; Waccasassa; Western Okeechobee Inflow; Withlacoochee; Withlacoochee; Yellow
GA1936202011Alapaha; Little Ocmulgee; Little Satilla; Lower Chattahoochee; Lower Flint; Lower Savannah; Middle Chattahoochee-Walter F; Middle Flint; Ogeechee Coastal; Suwannee; Withlacoochee
ID20042004*
LA1980202021Amite; Atchafalaya; Bayou Teche; Bogue Chitto; East Central Louisiana Coastal; Eastern Louisiana Coastal; Lake Maurepas; Lower Calcasieu; Lower Grand; Lower Mississippi-New Orleans; Lower Ouachita; Lower Pearl; Lower Red-Lake Iatt; Lower Sabine; Mermentau; Mermentau Headwaters; Saline Bayou; Toledo Bend Reservoir; Vermilion; West Central Louisiana Coastal; Whisky Chitto
MA194119411Narragansett
MN189018901Twin Cities
MS199920217Escatawpa; Homochitto; Lower Pearl; Pascagoula; Tangipahoa; Upper Leaf; Upper Tombigbee
MO201820181Lower Missouri-Crooked
NH197619761Piscataqua-Salmon Falls
NM199419941El Paso-Las Cruces
NY189318991Sandy Hook-Staten Island
OH201720171Cuyahoga
OK198919891Arkansas-White-Red Region
PR195520073Cibuco-Guajataca; Culebrinas-Guanajibo; Southern Puerto Rico
SC199720196Calibogue Sound-Wright River; Cooper; Lake Marion; Lower Savannah; Salkehatchie; Santee
TN200920091Pickwick Lake
TX1992201911Austin-Travis Lakes; Buffalo-San Jacinto; Caddo Lake; Lower Angelina; Lower Neches; Lower Sabine; Lower Trinity; Middle Sabine; Sabine Lake; West Fork San Jacinto; Wichita

Table last updated 8/14/2022

† Populations may not be currently present.

* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).


Ecology: 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 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 embedded 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.

This species 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: 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, as either a sale item or a contaminant. Secondary introductions are likely due to hitchhiking on animals and boats.


Status: Occasional populations rarely reported within the Great Lakes basin, but this species has not been reported to overwinter in the region.


Great Lakes Impacts: Salvinia minima has a high probability of introduction to the Great Lakes (Confidence level: high).

Potential pathway(s) of introduction: Stocking/planting/escape from recreational culture, escape from commercial culture, unauthorized intentional release, hitchhiking/fouling.

This species is commonly grown by aquarium and pond owners (Global Invasive Species Database, 2021), and is very commonly sold online through sites like eBay and Amazon. Synonym S. rotundifolia is cultured and sold in Ohio. Salvinia minima is still widely available in the water garden trade, either as a sale item or as a contaminant. Although it continues to infest new regions, it is not included on the Federal Noxious Weed List and is prohibited only in the states of Texas (Tex. Admin. Code §57.112 and §19.300) and Louisiana (La. Admin. Code tit. 76 § VII-1101) (USGS). It is commonly associated with commercially sold species, with one study showing it as a contaminant or hitchhiker up to 25% of the time in the sale of other species of retail aquatic plants (Maki and Galatowitsch 2004).

Status: Occasional populations rarely reported within the Great Lakes basin, but this species has not been reported to overwinter in the region.

Salvinia minima has a moderate probability of establishment if introduced to the Great Lakes (Confidence level: high).

While this species is highly adaptable to a variety of environmental variables and conditions, persistent low temperatures and ice cover in the region would provide significant barriers to establishment (Dickinson and Miller 1998; Flowgrow Aquatic Plant Database, 2021).

Great Lakes Impacts:

Salvinia minima has the potential for high environmental impact if introduced to the Great Lakes.
Mats of this plant can decrease oxygen concentration and block out sunlight, harming fish and other aquatic organisms in the area. Furthermore, die-offs of this species can reduce dissolved oxygen content in the surrounding area (Texas A&M AgriLife Extension, 2020). During earlier stages of colonization, Salvinia minima demonstrates exponential growth rates (Gaudet 1973). In Texas and Louisiana, S. minima typically occurs in dense, expansive populations and is known as a very troublesome weed that can completely blanket waterways (Jacono et al. 2001). Mats in Louisiana have been measured as thick as 20-25 cm (Montz 1989). 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.). 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 the other species 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). In Texas, S. minima was observed shading out some submersed plant species (Jacono et al. 2001).

Salvinia minima has the potential for high socioeconomic impact if introduced to the Great Lakes.
Salvinia minima can clog water intakes for industry and power production if it forms dense surface mats (Jacono 2003). It can also negatively affect fisheries by changing macrophyte composition and reducing oxygen concentration (Texas A&M AgriLife Extension, 2020). Salvinia minima can restrict boating and impede waterway access due to excessive surface growth (Global Invasive Species Database, 2021).

Salvinia minima has the potential for moderate beneficial impact if introduced to the Great Lakes.
This species is sold as a common, inexpensive aquarium plant, and is often used in home aquariums in planted tanks due to its hardiness and ability to absorb excess nutrients (Global Invasive Species Database, 2021; Flowgrow Aquatic Plant Database, 2021).


Management: Management:
Regulations (pertaining to the Great Lakes region)
No Great Lakes-specific regulations currently exist for this species.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control
 

Biological
Biological control efforts for S. minima have focused on the salvinia weevil, Cyrtobagous salviniae, which is native to South America. It was introduced accidentally in Florida, a state in which water spangles are widespread but considered manageable. The manageable level of salvinia species, including both S. minima and Salvinia molesta (giant salvinia), is thought to be caused by the presence of these weevils, which live and feed on the salvinia leaves (Jacono et al. 2001).
The effects of these weevils on S. minima were compared to the effects of the salvinia stem-borer moth, Samea multiplicalis, which is a species native to the southern United States and is known to feed on other salvinia species in the same genus. Both the moth and the weevil feed on salvinia plants and control their spread (Tewari and Johnson, 2011). The lack of recorded detrimental environmental effects makes biological control methods the most promising in the long-term management of S. minima. Research continues to try to identify cold-tolerant populations that may be more suited to the region (Cozad et al 2019).

Physical
Mechanical methods include the physical removal of S. minima from areas where it is established, including raking the surface of the water or using large seine nets for removal. Mechanical methods have proven mostly ineffective because any fragments left behind will regrow, in addition to the difficulty of maneuvering equipment around small waterways (Texas A&M AgriLife Extension, 2020).

Chemical
Chemical herbicides that have been used with the best success on S. minima include the ingredients carfentrazone, copper complexes, diquat, fluridone, flumioxazin, glyphosate imazamox, and penoxsulam (Texas A&M AgriLife Extension, 2020). Some of these herbicides kill S. minima more successfully when a surfactant is added to make the chemicals stick to the surface of the leaves. However, if a large area of S. minima is sprayed with an herbicide all at once, the dead plant matter will sink and decompose, which can deplete oxygen in the water and result in fish kills and harm to other aquatic life. Smaller sections can be sprayed in sequence to reduce this side effect (Texas A&M AgriLife Extension, 2020).

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.


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, and C. Mudge. 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. and T.E. Miller. (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 C.C. Jacono. 2000. Status of Salvinia (Salviniaceae) in Alabama. Castanea 65:225–227.

Jacono, C.C., Davern, T.R. and T.D., Center. 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.

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.

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.

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.

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/

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 M.J., Eubanks. 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.


Author: Lower, E.


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Revision Date: 6/10/2021


Citation for this information:
Lower, E., 2022, Salvinia minima Baker: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatlakes/FactSheet.aspx?Species_ID=297&Potential=Y&Type=2&HUCNumber=DGreatLakes, Revision Date: 6/10/2021, Access Date: 8/14/2022

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.