Vascular Plants (C. C. Jacono)

Nonindigenous aquatic plants often act as stressors of aquatic ecosystems. Many form large colonies that alter the abundance and diversity of the native flora or disturb physical and biological functions such as water flow, light penetration and dissolved oxygen content.  Although not all introduced aquatic plants share these extreme abilities, the consequences of most introductions have yet to be understood.  Fundamentally, the establishment of nonindigenous plants preempts habitat for native species.  As new taxa are introduced and the range of previously established species increases, detailed knowledge of their distribution and potential range is imperative for resource management.

The following summary provides an inventory of all freshwater aquatic vascular plants that have become established (i.e. naturalized) in the southeastern Region 4. It provides specific information on regional species included in the Nonindigenous Aquatic Species (NAS) database (http://nas.er.usgs.gov/plants), an online inventory developed for tracking introductions in the United States.

This report, like the NAS database, is based on occurrence data derived from monitoring programs, herbarium vouchers, published accounts and professional observations.  The geographic distribution of many of the species is only superficially understood, mainly due to significant gaps in plant collection and monitoring data. Any increase in the collection and provision of spatial data would promote a better determination of the geographic coverage of aquatic plant introductions at both regional and national levels.

USFWS Region 4 is defined by hundreds of drainages categorized under the USGS Hydrologic Unit Code level 8 (HUC 8). In this report HUC 8 drainage names are commonly used to describe distribution.  Temperate species from Europe and cooler Asian climates define the majority of introduced species in Kentucky, Tennessee and the Southern Appalachians. The more southerly states host a wider variety of plants, the majority being of subtropical and tropical origin. Many of these species are found to perenniate in the warm temperate zones of Georgia, Arkansas and North Carolina.

In this report, 60 vascular freshwater plants species, representing 29 families are catalogued as introduced in Region 4.  The number of taxa would be much higher if the inventory were not restricted to true aquatics, i.e. those plants that grow with some of their photosynthetic portions submerged or floating in water.

All species considered not indigenous to the region are included.  A few taxa, namely Marsilea vestita and Nymphaea mexicana, are native to other parts of North America.  Geographic distributions differ greatly from species such as Limnophila indica, that have a limited occurrence in Region 4, to broadly ranging species like Hydrilla verticillata.  New, potentially weedy plants such as Salvinia molesta, Marsilea minuta, and Nymphoides hydrophyllum are highlighted for Region 4, to assist resource managers with early detection. Well-established species such as Najas minor, Egeria densa and Murdannia keisak also merit attention for their potential to inhabit new regions. 

This report is contained in three sections.  Section 1 is a matrix listing all nonindigeous aquatic plant species recorded in ten states of Region 4.

Section 2 is of a list of plants known from USFWS refuges in Region 4.  The species name is followed by the earliest date of known occurrence.

Section 3 provides the earliest records of plant species occurring in each state, along with origin notes, distribution summaries, and pertinent comments on individual species.

The early occurrence records provided in Section 3 fall into three categories. The categories are depicted in bold type, standard type, or standard type with an asterisk.  Dates in bold type indicate the verified first occurrence of a species in a state.  When an occurrence is not verified to be the first, standard type is used to indicate the earliest record known to the author.  Standard type followed by an asterisk (i.e. 1986*) is used for literature citations, which document the earliest occurrence record known to the author, but do not represent a collection date.

Additional records of nonindigenous species from refuge or other lands and waters are welcomed at: http://nas.er.usgs.gov/reportcol.htm.  Contact Colette_Jacono@usgs.gov for identification or verification of plant material.

Section 1.   Nonindigenous Aquatic Plant Species in States of Region 4. - click to enlarge

Section 1. (continued) - click to enlarge

Section 2.  Nonindigenous Aquatic Plant Species at Region 4 Refuges. - click to enlarge

Section 3.  Summary of Nonindigenous Aquatic Plants in Region 4.

Acanthaceae

Hygrophila polysperma - Indian hygrophila                                                                             Asia

AL AR FL GA KY LA MS NC SC TN     1965

Comments:

Highly invasive. Ranging through peninsular to northern Florida at more than 40 locales, including 22 flowing rivers and streams.  Most southern parts of Region 4, mainly Gulf and Atlantic Coastal Plains, potentially vulnerable.  Recognize by opposite, elliptical leaves, sessile to the stem.  Submersed stems round, terrestrial becoming more square.

Alismataceae

Sagittaria guyanensis - Guyana arrow-head                                         South & Central America

AL AR FL GA KY LA MS NC SC TN           1993*

Comments:

Collected from rice fields of south central Louisiana; likely not of concern.

Sagittaria montevidensis - long-lobed arrow-head                                               South America

AL AR FL GA KY LA MS NC SC TN 1968*   1977 1939       1968* 1968*

Comments:

Older, sporadic collections near seaports may not represent persisting populations.  However, presence in the water-garden industry could serve as an introduction source for more recent and future populations.  Plants to 1m high.

Amaranthaceae

Alternanthera philoxeroides - alligatorweed                                                           South America

AL AR FL GA KY LA MS NC SC TN 1897 1988* 1894 1965 1986 1946 1949 1967 1957 1975

Comments:

Long established yet still expanding in range; new to western Kentucky in 1986 and Oklahoma in 1996. Invasive in aquatic and wetland habitats. Forming floating tangles of hollow stems in streams, marshes, and lakes.   Perenniates vegetatively; rarely reproduces by seed. Northern distribution mainly limited by cold tolerance of herbaceous above ground parts.

Araceae

Colocasia esculenta - wild taro                                                                                     Asia Tropics

AL AR FL GA KY LA MS NC SC TN 1981   1958 1985   1986 1994   ?

Comments:

Emergent aquatic and semi-aquatic with wide ecological amplitude in respects to habitat. Increasing in Gulf Coast regions to northern Louisiana, lower halves of Mississippi, Alabama and Georgia. Rapid colonization throughout Florida since the late 1950s and early 1960s.  Three varieties newly described in the southeast; characterized by tubers, rhizomes and habitat.  Colocasia is often confused with other non-natives aroids, namely Alocasia and Xanthosoma (Serviss et al. 2000).  Reproduction vegetative, rarely by seed.  Poisonous calcium oxylate crystals deposited throughout the plant, especially in tubers.

Cryptocoryne wendtii - water-trumpet                                                     Asia Tropics - Sri Lanka

AL AR FL GA KY LA MS NC SC TN     1989

Comments:

Rooted rosettes, submersed and locally abundant on limestone and organic substrate at high flow spring in Florida. Dense colony expanding by rhizomes at that site; habitat similar to that of the closely related and similarly introduced Cryptocoryne beckettii, in ripples and pools of spring fed San Marcos River, Texas (Rosen 2000). Popular aquarium plant; likely expanding from cultivation.
 

Cryptocoryne wendtii submersed in Florida.

Pistia stratiotes - water-lettuce                                                                                       Pan tropical

AL AR FL GA KY LA MS NC SC TN     1765     1969 1999   1991

Comments:

Free floating, velvety rosettes; prolific grower.  Absence of indigenous, host specific insects indicates Pisita as introduced to the U.S. (Dray et al. 1993); introduction by birds has not been discounted. Range recently expanding to include Mississippi, persisting there along a creek in Madison Co., (Middle Pearl-Strong River drainage); also persisting in eastern South Carolina along the Waccama River.  Frost intolerant; sexual reproduction important for the dynamics of some populations in the Netherlands, Australia, and Florida (Harley 1990, Dray and Center 1989); seeds survived prolonged experimental periods in water at 4^oC and a few weeks in ice at –5^oC; germination occurred between 20^oC and 25^oC (Pieterse 1981). With appropriate substrate and hydrologic conditions, overwintering by seed could account for population reoccurrence in temperate regions of the U.S.; seedlings are light green and pubescent.
 

Pistia stratiotes: mature plant (left); flowering spathe (center), seedlings
with Wolffia and Lemna (right, seedling photo courtesy T. Center, USDA, ARS).

Brassicaceae

Nasturtium officinale - water-cress                                                                                         Europe
= Rorippa nasturtium-aquaticum

AL AR FL GA KY LA MS NC SC TN 1944* 1978* 1929 1951 1944* 1972 1969 1944* 1944* 1959

Comments:

Established in the US by the mid 1800s as a submersed plant in cold water streams and springs. Dense, leafy stands may alter function and flow in shallow streams. Sometimes confused in Florida with the indigenous Nasturtium microphyllum (Rorippa floridana).   Nasturtium officinale is distinguish by pods bearing a double row of seeds, while N. microphyllum bears a single row of seeds in narrow pods.

Butomaceae

Hydrocleys nymphoides - water-poppy                                                     South America - Brazil

AL AR FL GA KY LA MS NC SC TN     1989

Comments:

Scattered collections from central Florida are likely water-garden escapes.  Plants appear similar to the native Limnobium spongia, yet have large yellow flowers. In 1989 found forming 0.25-acre mat in an Orange Co. wetland; status there unknown.

Callitrichaceae

Callitriche stagnalis - pond water-starwort                                                                           Europe

AL AR FL GA KY LA MS NC SC TN 1980                 1997*

Comments:

Introduced since late 1800s in dry ballast.  Expanding to a 500 mile range in northeastern US; ranging south to Maryland with disjunct southern locals recent in Tennessee and Alabama (namely the Middle Tennesee-Elk River drainages).  Submersed and mat forming in streams, ditches, and ponds. Seeds prolific in plant dispersal. Distinguish from native Callitriche by round fruits with a marginal wing. Potential exists for the species to become a nuisance in cooler zones of Region 4 (Philbrick et al. 1998).

Commelinaceae

Murdannia keisak - marsh dewflower                                                                                       Asia

AL AR FL GA KY LA MS NC SC TN 1980s 1960s 1960s 1950s 1986* 1981 1980s 1950s 1930s 1976

Comments:

Competitive emergent; forming locally dominant colonies in marshes and along stream and reservoir margins. Found rooted in water up to 1.5 m deep, with trailing stems to 1 m long.  Expanding from eastern Carolinas through the southeast, north to Maryland and Virginia. Introduced with early rice farming.  Reproduction both vegetative and by small, abundant seeds. Most parts of Region 4 likely vulnerable.

Convolvulaceae

Ipomoea aquatica - water-spinach                                                                               Asia - Tropics

AL AR FL GA KY LA MS NC SC TN     1987

Comments:

Scattered locales exist in Florida only. Aggressive vine-like species with floating stems that spread over the surface of canals, streams and lakes.  Cultivated by Asian Americans for its edible green leaf with high protein content.

Cyperaceae

Cyperus alopecuroides - foxtail flatsedge

AL AR FL GA KY LA MS NC SC TN     1993

Comments:

In Polk Co., Florida, a single local at a phosphate pit in the Peace River drainage, forming abundant floating mats and emerging in shallow water along wetland edges (Carter et al. 1996).

Cyperus prolifer - dwarf papyrus                                                                                               Africa

AL AR FL GA KY LA MS NC SC TN     1993

Comments:

Newly introduced and apparently spreading. Known from lakes in the Kissimmee, Peace, Hillsborough River and Tampa Bay drainages. Growing at shorelines and forming floating mats; water-garden escape (Carter et al. 1996).

Haloragaceae

Myriophyllum aquaticum - parrot-feather                                                                 South America

AL AR FL GA KY LA MS NC SC TN 1970 1970 1918 1951 1986* 1970 1944 1958 1968* 1959

Comments:

A favorite in the water-garden trade, this species readily escapes cultivation to form weedy masses in ponds, swamps and streams.  Becomes terrestrial with water draw-down. Common throughout Florida, Louisiana and Alabama. Extending north to central Mississippi, much of Arkansas and Tennessee. Found in Georgia north through the Ridge and Valley Province, including the Upper Ocmulgee and Upper Coosa River drainages where plants occur at 950 ft. elevation.   Known in the Carolinas west to the Piedmont.  Occurrence in the Lower Susquehanna drainage of Pennsylvania and the Upper Ohio River drainage of West Virginia suggests vulnerability throughout Region 4. Absence of male plants in US implicates reproduction by vegetative propagules only.

Myriophyllum spicatum - Eurasian water-milfoil                                                                 Europe

AL AR FL GA KY LA MS NC SC TN 1963 1997 1964 1966 1977 1979 1979 1966 1987 1955

Comments:

The most problematic species in northern US, forming tangled, submersed stands.  Well established in the Tennessee and Cumberland River systems of Kentucky and Tennessee.  Common in reservoirs of Kentucky (including the Ohio and Green River drainages), Alabama (including Middle Alabama, and Middle Tombigbee drainages) and Mississippi (including Upper Tombigbee, Town and Tibbee drainages). New to Arkansas, at Lake Ouachita. In Florida, Louisiana and southern Alabama mainly occurring in estuaries of large rivers along the Gulf of Mexico.  Many Region 4 waterbodies, especially in cooler zones, are prone to infestation.  Lacking a current commercial market, new occurrences should be anticipated through spread from current infestations.

Hydrocharitaceae

Blyxa aubertii - blyxa                                                                                                   Asia & Australia

AL AR FL GA KY LA MS NC SC TN           1968

Comments:

Uncommon in a few lakes and ponds of southern Louisiana, apparently not of concern.

Egeria densa - Brazilian waterweed                                                                         South America

AL AR FL GA KY LA MS NC SC TN 1966 1979 1937 1979 1986* 1968* 1968* 1968* 1966 1959*

Comments:

Submersed perennial, forming aggressive, often dominant colonies.  May be out competed only by hydrilla in southern regions.  Similar in appearance and growth to hydrilla, recognize by whorled leaves exceeding 2cm and by fresh plants being smooth to the touch. Also established in Pennsylvania and southern Missouri.  Seed production not known in US, however plants effectively spread by fragments.  All parts of Region 4 are vulnerable.

Hydrilla verticillata - hydrilla                                Tropical and Temperate Asia, Northern Europe

AL AR FL GA KY LA MS NC SC TN 1978   1953 1967   1973 1987 1980 1982 1988

Comments:

Most critical invasive submersed species in Region 4.  Range greatly expanding due to the separate introduction of two biotypes that independently populate warmer and cooler regions of the U.S. "Warm region" type spreading from Florida through southern states; "cooler "region" type extending from North Carolina to northern Pennsylvania, and west across the Appalachian divide into the Tennessee and Ohio River drainages.  Recognize by many toothed leaves, arranged in a whorl that do not exceed 1.5 cm in length; usually having midrib spines that give plants a rough touch.

Distribution of hydrilla biotypes in U.S. by drainage basin (USGS HUC 8) (Madeira, et al. 2000).

Ottelia alismoides - duck-lettuce                                                                 Asia, Australia & Africa

AL AR FL GA KY LA MS NC SC TN           1969

Comments:

First discovered in rice field ditches of Cameron Parish in 1969.  Recorded from four additional western Parishes in the Calcasieu-Mermentau drainage by 1993. Expanding east by 1986 to the Bayou Teche drainage and the East Central coastal drainages, the including the Barataria Basin. At lake, marsh ponds and canals, a completely submersed, rooted rosette with broad leaves on long petioles.  Plants do not tolerate drying out.  Lacking specialized organs for vegetative reproduction, plants reproduce solely by seed. Flowers submersed or emersed.  Local populations probably not displaying the aggressiveness anticipated; population at Lake Chicot  only ~18 sq. m.

Iridaceae

Iris pseudacorus - yellow iris                                                                                     Europe & Africa

AL AR FL GA KY LA MS NC SC TN 1988* 1988* 1943 1997* 1986* 1972*   1967   1993*

Comments:

Widespread in northeastern U.S.  More southern collections are highly scattered and likely represent garden escapes. A cool climate invasive, potentially problematic in warm zones of Region 4 at cold spring fed, riparian habitat similar to that at the Frio River, Texas.  Emergent in shallow streams, creek flats, marshes and lake shorelines.  Identify yellow flower by 3 inner tepals being much shorter and more upright than the 3 large, outer tepals (called falls).

Iris pseudacorus, Frio River, Texas. Photos courtesy C. Lee, USFWS

Lemnaceae

Landoltia (Spirodela) punctata - dotted duckweed                                           Asia & Australia

AL AR FL GA KY LA MS NC SC TN 1976 1974 1945 1965 1985* 1961 1974* 1981* 1981* 1986*

Comments:

Well established in the southeast, expect throughout Region 4. Often overlooked due to resemblance to native duckweeds. Considered a "pioneer species" in that this species colonizes quickly, has a high rate of vegetative propagation and is distributed easily (Landolt 1986).  Impact on natives not known; often found in pure stands.
 

Landoltia punctata has fronds appearing smaller
and more elongated than the native Spirodela polyrhiza.

Lythraceae

Lytrhum salicaria – purple loosestrife                                                                                   Eurasia

AL AR FL GA KY LA MS NC SC TN 1978 1985*     1896   1999 1885   1899

Comments:

Cool zone marsh weed, not tolerating hot, humid climates of Region 4 coastal plains. Ten North Carolina populations, yet, only those in the mountains and piedmont established and aggressive. Northern Alabama, Huntsville, is the most southern Region 4 local. Plants also found recently in northeastern Mississippi, near Corinth, at roadside ditch and ponds.

Rotala indica – Indian toothcup                                                                                                   Asia

AL AR FL GA KY LA MS NC SC TN           1971

Comments:

Rice field weed, sometimes escaping to ditches and wet prairies. Known in five southern Parishes of Louisiana, all draining the headwaters of the Mermentau River.  Submersed or terrestrial, annual species with axillary reddish flowers. Perhaps more abundantly established in California rice regions than in Louisiana. In Italy, where also introduced, found to be nearly ubiquitous in rice fields, yet rarely straying from them (Cook 1973). Incorrectly advertised by the water-garden trade to be the same as Rotala rotundifolia. However R. rotundifolia is a perennial species with a racemose inflorescence and rose colored flowers (Cook 1976).  It is being promoted for water-gardens in Florida and southern Louisiana, where it can be expected to perenniate.

Marsileaceae

Marsilea ancylopoda, M. hirsuta, M. macropoda, M. vestita

Comments:

Identification and distribution of introduced North American (western) and exotic Marsilea species under investigation at USGS/FISC.

Marsilea minuta – small water-clover                                                      Africa and Tropical Asia

AL AR FL GA KY LA MS NC SC TN     1992 1993

Comments:

New to U.S.  First recorded in the Pensacola Bay drainage, Florida (Burkhalter 1995), later collected in the Middle Chattahoochee-Lake Harding drainage in northern Georgia and most recently in the Briar drainage of eastern Georgia. Status under investigation at  USGS/FISC.  Submersed to terrestrial fern, forming locally abundant colonies along water margins. Leaves appearing like a four-leaf clover.  Larger floating leaves develop on long petioles; terrestrial leaves having crenate margins and are held erect. A widespread and important weed in tropical Asia; to be looked for in southern zones of Region 4.

Marsilea minuta, small water-clover, terrestial form, USGS.

Marsilea quadrifolia – European water-clover                                                                   Eurasia

AL AR FL GA KY LA MS NC SC TN         1920

Comments:

Northern invasive, submersed to terrestrial fern.  Known from the Upper Green and Northern Kentucky River drainages of Kentucky. Expected only in the colder zones of Region 4. Fruiting structures (sporocarps) required for identification of all Marsilea species.

Menyanthaceae

Nymphoides cristata – crested floating heart                                                           Asian tropics

AL AR FL GA KY LA MS NC SC TN     1996

Comments:

New, weedy, floating-leaved species in lakes and canals of central and southern Florida (Jagger pers. comm.; Burks 2000). Distinguish from the native Nymphoides by  flower petals having a crested wing along the center of the inner surface. Populations expand vegetatively by rhizomes and by bulbils produced on leaves (Sivarajan and Joseph 1993).  Water-garden escapes should be watch for in Region 4 coastal plains.

Nymphoides cristata, crested floating heart.
Photo courtesy V. Ramey, U/FL Center for Aquatic and Invasive Plants.

Nymphoides indica – water snowflake                                Tropics of America, Asia and Africa

AL AR FL GA KY LA MS NC SC TN     1998*

Comments:

Collected from Manatee Co., Florida. Distinguish from native Nymphoides by flower petals with long, soft hairs covering the inside surface (petals of native Nymphoides are smooth on the inner surface) (Wunderlin 1998; Sivarajan and Joseph 1993).

Nymphoides peltata – yellow floating heart                                                                       Eurasia

AL AR FL GA KY LA MS NC SC TN   1939     1986*   1955

Comments:

Floating-leaved invasive, well established in the northeastern US, apparently not persisting in southern zones of Region 4.  Early collections from Louisiana and Mississippi do not represent current populations.  More adapted to northwestern Arkansas where a 1939 collection from a lake in the Illinois River  was still persisting in 1954. Rare occurrences recorded in lakes and ponds in the Lower Ohio-Salt River drainage of Kentucky.  A water-garden favorite.  Naturally dispersal by seed; seeds float when wet, are picked up and transported by waterfowl, detach and sink to germinate when the bird returns to water (Stuckey 1973-74; Cook 1990).

Najadaceae

Najas minor – brittle naiad                                                                                                     Europe

AL AR FL GA KY LA MS NC SC TN 1944* 1979* 1958 1951 1986* 1980 1979 1997 1969 1944*

Comments:

Submersed; potentially invasive both widely or locally; many branching stems may fill the water column; earliest Region 4 occurrences in Tennessee River system, expanding since then in Alabama and Tennessee; abundant in impoundments of central North Carolina (Haw and Upper Neuse River drainages) and central South Carolina. (Saluda River and Lake Marion drainages); common in northern and western Georgia; more suited to cooler zones, becoming less common northern to central Florida, Mississippi and Louisiana; identify by seeds at leaf axils; reproducing prolifically as an annual by seed; seeds survive drought; plant tolerates pollution, turbidity and depths greater than 3.5 m; infestations develop in late summer.

Nelumbonaceae

Nelumbo nucifera – sacred lotus                                                                                               Asia

AL AR FL GA KY LA MS NC SC TN 1901 1988* 1961 1951   1978 1971 1968* 1968* 1970*

Comments:

Sporadically escaping and spreading locally from cultivation.  Identify by flower petals pink compared to yellow for the native Nelumbo lutea.

Nymphaea ampla, N. capensis, N. lotus, N. x daubeniana

Comments:

Exotic water lily species and hybrids occasionally escaping ornamental cultivation to become locally established in Florida and Louisiana.

Nymphaea mexicana – banana water-lily                                                                 North America

AL AR FL GA KY LA MS NC SC TN               1968* 1968*

Comments:

Native south/western; yellow flower; escaping ornamental cultivation north of its natural range; primarily at impoundments in the outer coastal plain, Carolinas.

Onagraceae

Ludwigia hexapetala – Uruguay seedbox                                                 North/South America ?

Comments:

Recorded for all states in Region 4; potentially native, status under investigation; problematic at reservoirs in the Lake Marion and Cooper River drainages of eastern South Carolina.

Parkeriaceae

Ceratopteris thalictroides – water sprite                                                                                   Asia

AL AR FL GA KY LA MS NC SC TN     1878     1972*

Comments:

Fern; rooted or floating; lakes and slow moving waters; peninsular Florida, north to the St. Johns River drainage in the east and to the Withlacoochee River drainage in the west; perhaps less common in coastal regions of southern Louisiana; also known from Hawaii, California and central Texas; plantlets form along leaf margin; similar native species, Ceratopteris pteridoides has inflated, slightly wider petioles.

Poaceae

Urochloa (Brachiaria) mutica – para grass                                                                             Africa

AL AR FL GA KY LA MS NC SC TN     Early   1900s           After 1968

Comments:

Introduced for pasture grass.  Hollow stems form floating mats in aquatic systems; out competes native shoreline species. Distributed throughout peninsular Florida, especiallly problematic in drainage canals. Also found in lakes, marshes and rivers; tens of thousands of acres burned in Lake Okeechobee this season.  Status of a single collection from Aiken Co., South Carolina, unknown, perhaps not representing an aquatic site.

Hymenachne amplexicaulus – West Indian marsh grass                 South & Central America

AL AR FL GA KY LA MS NC SC TN     1968*

Comments:

Robust, emergent grass.  First documented as part of the Florida flora in the 1960’s and 70’s. Not becoming more frequent until the mid 1990s when recorded at marshes, rivers and drainage canals in six drainages of central and southern Florida.  Extending north to the Myakka and the Crystal-Pithlachascotee River drainages.  Found forming monocultures to the displacement of native species.  Tolerates extensive periods of flooding and drought.  Dispersal by seed; seeds float [Langeland and Burks (eds.) 1998].

Hymenachne amplexicaulis, photos courtesy V. Ramey,
U/FL Center for Aquatic and Invasive Plants.

Luziola peruviana – Peruvian watergrass                                                             South America

AL AR FL GA KY LA MS NC SC TN     1901     1882

Comments:

Shallow ponds, ditches and miry places.  Low growing grass, almost always in standing water with leaf blades floating.  Occurrence local and infrequent; limited to the Lower Mississippi and coastal drainages of Louisiana and the Pensacola Bay drainage of Florida.

Oryza sativa – rice                                                                                                                           Asia

AL AR FL GA KY LA MS NC SC TN           1993*   1968* 1968*

Comments:

Escaping locally from rice cultivation; not of concern.

Panicum repens – torpedo grass                                                                                         Australia

AL AR FL GA KY LA MS NC SC TN 1876   Cultivated in 1920s     1971 1971 1969 1987 1987

Comments:

Invasive grass displacing native species in marshes and along shorelines mainly throughout Florida.  Not spreading much beyond the coast in Alabama, where it was first recorded in the Mobile Basin. Otherwise scattered northward along the Atlantic Coast to North Carolina.  Initially planted for forage in wet pasture.

Pontederiaceae

Eichhornia crassipes – water-hyacinth                           South America - Upper Amazon Basin

AL AR FL GA KY LA MS NC SC TN 1947* + 1890s 1947* + 1933 1916 1947* 1947* +

Comments:

Floating invasive with thick, glossy leaves. Distributed throughout Gulf Coastal plain, including entire states of Louisiana and Florida. In Mississippi extending north to the Big Sunflower drainage in the west and to Columbus Lake in the east.  Ranging through central Alabama to the Coosa River drainage.  In Georgia extending north in to the Upper Ocmulgee River drainage; perenniating in coastal tidewater regions of Georgia and South Carolina where marshes were diked. Persisting in southeastern North Carolina after harsh winters, extending there into the Piedmont during warm years.  More recently persisting in coastal Virginia.   Several populations in southern Arkansas, southwestern Tennessee and Kentucky were temporary, not surviving the winter.  In cooler regions, including northern Mississippi and Alabama, this species may have the potential to reappear annually by seed.

U.S. Distribution of water-hyacinth, Eichhornia crassipes.

Potamogetonaceae

Potamogeton crispus – curly pondweed                                                                               Europe

AL AR FL GA KY LA MS NC SC TN 1943 1988* 1937 1947 1973 1949 1979 1950 1990 1946

Comments:

Aggressive, cool climate, totally submersed perennial. Established in northeastern US ~160 yrs (Stuckey 1979).   Florida populations infrequent and short lived.  In cooler regions, life cycle described by  turion production and plant die-back by mid-summer, followed by turion germination in the fall for seedlings to over winter and serve as colonizing species in the spring.  Tolerates pollution, turbidity, and deep water. Distinguish from native pondweeds by serrated leaf margins. Expect in cooler zones of Region 4.

Salviniaceae

Salvinia minima – water spangles/common salvinia                           Central & South America

AL AR FL GA KY LA MS NC SC TN 1982 1998 1930 1936   1980 1999   1998

Comments:

Free floating fern with oval leaves and velvety hairs. Introduced 1928 to Florida (St. John's River drainage), currently expanding to 73 drainages in eight southern states.  Extremely problematic in Louisiana and Texas. Florida populations less problematic, probably due to feeding damage by the Salvinia weevil, which is not fond in other states (Jacono et al.  2001). Distinguish from S. molesta by hairs on the upper leaf that are spreading - not attached at the tips.

Salvinia minima, U.S. Distribution by USGS HUC 8 Drainages.

Salvinia molesta – giant salvinia                                                                                South America

AL AR FL GA KY LA MS NC SC TN 1999   1999 1999   1998 1999 2000

Comments:

Free floating fern, about two times larger than Salvinia minima.  Distinguished by leaf hairs that are joined at the tips to form an eggbeater-like cage. Highly adapted invasive weed of tropics and warm-temperate zones; forms impenetrable monoculture covering water surface. Since 1998 found at >60 locations in 29 drainages of ten states (including Texas, Arizona, California and Hi).  Originating from water-garden trade, quickly dispersed in nature through flooding and by man (Jacono 1999; Haynes and Jacono 2000).

Mature specimens of Salvinia minima (left) and Salvinia molesta (right), USGS.

Scrophulariaceae

Bacopa egensis – Brazilian water-hyssop                                Central & South America, Africa

AL AR FL GA KY LA MS NC SC TN           1930

Comments:

Distributed in shallow, quiet waters of Bayou Tech and in the Lower Ouachita, Lower Red and Little River drainages of central Louisiana.  Frequently intermingled with the native and somewhat similar Bacopa rotundifolia; B. egensis differs in having tapering leaves with crenate margins (Depoe 1969).

Dopatrium junceum – dopatrium                                                                                                 Asia

AL AR FL GA KY LA MS NC SC TN           1969

Comments:

Restricted to rice fields of southern Louisiana. Inconspicuous, small, slender annual species; emersed in water up to 30 cm deep.

Limnophila indica – Indian marshweed                                                                                     Asia

AL AR FL GA KY LA MS NC SC TN     1983

Comments:

Recorded once from a Salix/Juncus marsh, Pinellas Co., Florida; also from Texas. Similar to Limnophila sessiliflora, differs by emersed stems having glands.  Distributed in the aquarium trade with L. sessiliflora.

Limnophila x ludoviciana – marshweed                                                      hybrid from cultivation

AL AR FL GA KY LA MS NC SC TN           1963

Comments:

Common where found at several rice fields, lakes and a cypress swamp in Louisiana. Known from the Bayou Tech drainage, the Mermentau headwaters and central coastal Louisiana. Suspected to be a horticultural hybrid between Limnophila sessiliflora and L. indica that was developed for aquaria.

Limnophila sessiliflora - Asian marshweed                                                                             Asia

AL AR FL GA KY LA MS NC SC TN     1961 1967

Comments:

Submersed, weedy species with the potential to develop large stands near the surface of relatively shallow, quiet waters.  Known from over 30 water bodies in central, south and the panhandle regions of Florida, including lakes, rivers and canals. In Georgia known only at Lake Seminole and a nearby pond.  Dispersed mainly through seed.  Flowering tips emersed; identify by emersed stems powdery and hairy. Expect in warmer zones of Region 4.

Limnophila sessiliflora submersed (left) and emersed with flowers (right).
Photos courtesy V. Ramey, University of Florida, Center for Aquatic and Invasive Plants.

Solanaceae

Solanum tapicense – wetland nightshade                                                            Central America

AL AR FL GA KY LA MS NC SC TN     1983

Comments:

Recorded from six counties in southwestern Florida.  Sprawling stems up to 5m with harsh, recurved prickles create impenetrable thickets along wetland streams and in moist cypress domes. Does not tolerating continuous flooding.  Believed to have the potential to spread and persist much farther north than southern Florida (Fox and Bryson 1998).

Solanum tapicense, photo courtesy V. Ramey,
Univ. FL, Center for Aquatic and Invasive Plants.

Literature Cited

Burkhalter, J.R. 1995. Marsilea minuta (Marsileaceae): new to Florida and North America. SIDA 16(3): 545-549.

Burks, K.C.  2000. Nymphoides cristata (Roxb.) Kuntze, new to the U.S. and occurring as a pest plant in Florida. Abstract in The ASB Bulletin.   47:171.

Carter, R., R.L. Mears, K. Craddock Burks. 1996. A report of four exotic Cyperus (Cyperaceae) species new to Florida, U.S.A. SIDA 17(1): 275-281.

Cook, C.D.K. 1973. New and noteworthy plants from the northern Italian ricefields. Ber. Schweiz. Bot. Ges. 83(1): 54-65.

Cook, C.D.K. 1976.  Revision of the genus Rotala.  Boissiera 29:1-156.

Cook, C.D.K. 1990.  Seed dispersal of Nymphoides peltata (S.G. Gmelin) O. Kuntze (Menyanthaceae).  Aquatic Botany 37:325-340.

Depoe, C.E. 1969.  Bacopa egensis (Poeppig) Pennell (Scrophulariaceae) in the United States.  SIDA 3(5):313-318.

Dray, F.A., T.D. Center and D.H. Habeck. 1993.  Phytophagous insects associated with Pistia stratiotes in Florida. Environmental Entomology 22(5):1146-1155.

Dray, F.A., Jr. and Ted D. Center. 1989.  Seed production by Pistia stratiotes L. (water lettuce) in the United States.  Aquatic Botany, 33(1989): 155-160.

Dunn, C.P. and R.R. Sharitz. 1990.  The history of Murdannia keisak (Commelinaceae) in the Southeastern United States. Castanea 55(2):122-129.

Fox, A.M. and Bryson, C.T.   1998. Wetland nightshade (Solanum tampicense): a threat to wetlands in the United States. Weed Technology 12:410-413.

Jaggers, B.V.  Florida Game and Fish Commission. Personal communication, Oct. 2000.

Jacono, C.C. 1999. Salvinia molesta (Salviniaceae) new to Texas and Louisiana. Sida 18(3): 927-928.

Jacono, C.C., T. R. Davern 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) in press.

Haynes, R.R. and C.C. Jacono.  2000. Status of Salvinia (Salviniaceae) in Alabama. Castanea 65(3):225-227.

Harley, K.L.S. 1990.  Production of viable seeds by water lettuce, Pistia stratiotes L. in Australia. Aquatic Botany 36:277-279

Langland, K.A. and K.C. Burks (eds.) 1998.  Identification and Biology of Non-Native plants in Florida’s Natural Areas. University of Florida, Gainesville, Fla. Pp. 165.

Landolt, E. 1986. The family of Lemnaceae - a monographic study. Vol 1. In: Biosystematic Investigations in the Family of Duckweeds (Lemnaceae). Veroff. Geobot. Inst. ETH, Stiftung Rubel. No. 71.

Madeira, P.T., C.C. Jacono and T.K. Van. 2000. Keeping track of hydrilla using two RAPD procedures and the nonindigenous aquatic species information resource. Journal of Aquatic Plant Management 38:33-40.

Philbrick, C.T., R.A. Aakiar, Jr. and R.L. Stuckey.  1998. Invasion and spread of Callitriche stagnalis (Callitrichaceae) in North America. Rhodora 100(901):25-38.

Pieterse, A.H., L. De Lange and L. Verhagen. 1981. A study on certain aspects of seed germination and growth of Pistia stratiotes L. Acta. Bot. Neerl. 30(1/2): 47-57.

Rosen, D.  2000. Cryptocoryne beckettii (Araceae), a new aquatic plant in Texas. SIDA 19(2):399-401.

Sivarajan V.V. and K.T. Joseph. 1993. The genus Nymphoides Sequier (Menyanthaceae) in India. Aquatic Botany 45:145-170.

Stuckey, R.L.  1979. Distributional history of Potamogeton crispus (curly pondweed) in North America.  Bartonia 46:22-42.

Stuckey, R.L. 1973-74. The introduction and distribution of Nymphoides peltatum (Menyanthaceae) in North America. Bartonia 42:14-23.

Serviss, B.E., S.T. McDaniel and C.T. Bryson.  2000. Occurrence, distribution and ecology of Alocasia, Caladium, Colocasia, and Xanthosoma (Araceae) in the southeastern United States. SIDA 19(1):149-174.

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

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.

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