• ChesReport (current)
  • Marine Invasions Lab
  • Partner Portals
    Nemesis California Panama Galapagos Cocos Island NP JTMD
    Archived Projects
    Chesapeake
  • Browse Species
    Taxonomic Groups All Species
  • News
  • login
You are viewing an archived site. The Chesapeake Bay Introduced Species Database project ended in 2020 and the database is no longer receiving updates. Learn more…
Image of Alternanthera philoxeroides

Alternanthera philoxeroides

Plants

Alligatorweed

Alligatorweed was likely transported to Mobile, AL on ships’ dry ballast (rocks and dirt used to weight a sailing vessel) in 1897 from South America (Brazil-Argentina) where it is native. It spread though much of the Southeast in the following years, reaching Hampton VA in 1953 on a load of asparagus from the Carolinas. The winters in much of the Chesapeake Bay region are too cold for this species so it is restricted to watersheds in the lowermost Bay. In the southeast, where it is more abundant, it was the target of a successful biological control program. As a result, it is largely controlled by several South American insect species brought in by the United States Department of Agriculture from 1964-71.

Image Credit: Wiki Commons

Description Taxonomy Invasion History Ecology Impacts References

Description

This plant is amphibious and can grow in dry soil, wet soil, or as a largely submersed creeping emergent (Julien and Broadbent 1980).


Taxonomy

Kingdom Phylum Class Order Family Genus
Plantae Magnoliophyta Magnoliopsida Caryophyllales Amaranthaceae Alternanthera

Synonyms

Telanthera philoxeroides; Bucholzia philoxeroides; Achyranthes philoxeroides

Invasion History

Chesapeake Bay Status

First Record Population Range Introduction Residency Source Region Native Region Vectors
1953 Established Expanding Introduced Regular Resident North America South America Agriculture(Agricultural Weed)

History of Spread

Alternanthera philoxeroides (Alligatorweed) is native to southern South America (Brazil-Argentina). There is an unsubtantiated record in FL in 1894, but the first confirmed record, in 1897, was on ship's ballast in Mobile AL. By 1901, it was recognized as a potentially troublesome weed in wet soils and shallow waterways in the southeast U.S. (Coulson 1977). Alternanthera philoxeroides invaded reservoirs of the Tennessee Valley authority in 1935, possibly spread by shipping from the Ohio and Mississippi Rivers. By the 1930's, it was present from FL north to NC and west to LA (Penfound 1940). By 1963, 162,400 acres of water were considered infested, and small populations were observed in VA, AR and CA. A biological control program is considered to have successfully controlled A. philoxeroides in much of the southeast (Buckingham 1996; Coulson 1977; Julien et al. 1995). However, the insects used, primarily the flea beetle Agasicles hygrophila, have not been established in NC (Buckingham 1996) and little or no control has occurred there (and probably also in VA). A. philoxeroides is considered to have reached the limits of its potential range in North America under present climate conditions but northward and inland expansion is likely with greenhouse warming (Julien et al. 1995). Alternanthera philoxerorides has been introduced to Puerto Rico, Asia (India-China), Australia, and New Zealand (Julien 1995).

In the Chesapeake Bay region, A. philoxeroides was first reported as a terrestrial weed (lawn pest) in Hampton VA, 'It is believed to have been brought from eastern Carolina with asparagus plants' (Massey 1957). By 1957, it was reported from Princess Anne and Isle of Wight Counties. The Fairfax County records are in Harvill et al. 1992, but not in the 1986 edition. In the Chesapeake Bay region. it is found around Back Bay (Virginia Beach County VA, an arm of Currituck Sound) and in the watershed around the lowermost Bay. Botanists whom we interviewed suspected that it was present in tidal fresh tributaries along the southwestern shore of the Bay (Silberhorn 1995; Ware 1996) but hadn't yet collected it.

History References - Buckingham 1996; Coulson 1977; Harvill et al. 1986; Harvill et al. 1992; Julien et al. 1995; Massey 1957; Penfound 1940; Silberhorne 1995; Ware 1996

Invasion Comments

Ecology

Environmental Tolerances

For SurvivalFor Reproduction
Minimum Maximum Minimum Maximum
Temperature (ºC) 12.0 36.0
Salinity (‰) 0.0 10.0 0.0 10.0
Oxygen hypoxic
pH
Salinity Range fresh-oligo

Age and Growth

Male Female
Minimum Adult Size (mm)
Typical Adult Size (mm) 2580.0 2580.0
Maximum Adult Size (mm) 5080.0 5080.0
Maximum Longevity (yrs)
Typical Longevity (yrs

Reproduction

Start Peak End
Reproductive Season
Typical Number of Young
Per Reproductive Event
Sexuality Mode(s)
Mode(s) of Asexual
Reproduction
Fertilization Type(s)
More than One Reproduction
Event per Year
Reproductive Startegy
Egg/Seed Form

Impacts

Economic Impacts in Chesapeake Bay

Alternanthera philoxeroides (Alligatorweed) apparently caused minor local problems as a terrestrial weed in lawns and asparagus fields in the Norfolk-Hampton VA area (Massey 1957). Abundance and economic impacts in Chesapeake region are presumably limited by climate, and could be altered by climate change (Julien et al. 1995). This species apparently has few or no beneficial impacts. It is on a list of 'invasive plants' of VA (Virginia Dept. of Conservation and Recreation 1996).

Alternanthera philoxeroides is resistant to herbicidal control of Eichornia crassipes (Water Hyacinth) in southeastern U.S. Chemical control programs for E. crassipes led to proliferation of A. philoxeroides which in turn prompted a successful biological control program (Coulson 1977). Alternanthera philoxeroides is now largely controlled by several South American insect species which were introduced by USDA in 1964-71 (Coulson 1977). Quoting a study of 102 sites in 10 southeastern states, Buckingham (1996) stated that ''Alligatorweed was not a major problem throughout the southeastern states in 1982', although there were locally serious problems. ... However, in the colder climates along the margin of alligatorweed's range, there has been little or no control reported except in the lower Mississippi Valley'.

Agriculture- Alternanthera philoxeroides can clog irrigation ditches and shallow waterways (U.S. Agricultural Research Service 1971). It also contaminates pastures, and can crowd out clovers and grasses. It is a weed in lawn turf fields, lawns and crop fields (Julien and Broadbent 1980; Massey 1957).

Boating- A. philoxeroides can interfere with boating in shallow water (Julien and Broadbent 1980; Penfound 1940).

Health - Dense growths reduce water circulation, and are favorable to mosquitos (Julien and Broadbent 1980; Penfound 1940).

Aesthetic - Aesthetic impacts have not been mentioned in the litereature we've reviewed, but dense floating mats and shoreline growths are probably unattractive.

Habitat Change- See 'Ecological impacts'.

References - Buckingham 1996; Coulson 1977; Julien and Broadbent 1980; Julien et al. 1995; Massey 1957; Penfound 1940; Agricultural Research Service 1971; Virginia Department of Conservation and Recreation 1995


Economic Impacts Outside of Chesapeake Bay

Alternanthera philoxeroides (Alligatorweed) is an important weed worldwide in tropical to warm-temperate regions; both as a terrestrial agricultural weed and as an aquatic plant affecting boating, irrigation canals, etc. (Buckingham 1996; Coulson 1977; Julien and Broadbent 1980; Penfound 1940). It caused 'millions' of dollars worth of damage to waterways in the US. The overall cost of United States Department of Agriculture biological control program was $1 million (1977 dollars) (Drea 1991).

References - Buckingham 1996; Coulson 1977; Drea 1991; Julien and Broadbent 1980; Penfound 1940


Ecological Impacts on Chesapeake Native Species

Abundance and ecological impacts of Alternanthera philoxeroides (Alligatorweed) in the Chesapeake Bay region are presumably limited by climate and could be altered by climate warming (Julien et al. 1995). Impacts noted in other areas include:

Competition- Rapid growth of A. philoxeroides can crowd out native plants (Julien and Broadbent 1980). In TN reservoirs, Alternanthera philoxeroides grew much faster than native Justicia americana (Water-Willow), its chief competitor (Penfound 1940). This species is on a list of invasive plants compiled by Virginia Department of Recreation and Conservation and VA Native Plant Society (Virginia Department of Conservation and Recreation 1999) and can be considered a potential competitor with other aquatic flora in its habitat.

Habitat Change- Alternanthera philoxeroides can produce dense growths in shallows and shorelines, and dense floating masses in shallow water. These floating mats reduce penetration of light and circulation, increasing accumulations of debris and sediment, promoting anoxic conditions (Julien and Broadbent 1980).

References - Julien et al. 1995; Julien et al. 1995; Penfound 1940; Virginia Department of Conservation and Recreation 1999


Ecological Impacts on Other Chesapeake Non-Native Species

Interactions of Alternanthera philoxeroides (Alligatorweed) with other exotic plants have not been studied in our region.

Food/Prey- A. philoxeroides is eaten by the introduced Hymenia recurvalis (Beet Webworm) in the southeast U.S. and Austrailia, but damage was insufficient for biological control (Coulson 1977; Julien et al. 1995). South American beetles (Agasicles hygrophila), moths (Vogtia malloi), and thrips (Amynothrips andersoni) were introduced to the southeast U.S. for biological control, but these did not survive in the northern parts of alligatorweed's range (NC). Most known insect control agents have a narrower climate range than A. philoxeroides (Coulson 1977; Julien et al. 1995).

References - Coulson 1977; Julien et al. 1995


References

Agricultural Research Service (1971) Common weeds of the United States., In: (Eds.) . , Washington, D.C.. Pp.

Buckingham, Gary (1996) Biological control of Alligatorweed, Alternanthera philoxeroides, the world's first aquatic weed success story, Castanea 61: 232-243

Coulson, Jack R. (1977) Biological control of alligatorweed, 1959-1972: a review and evaluation, , Washington, D.C.. Pp.

Drea, John J. (1991) The philosophy, procedures, and cost of developing a biological control of weeds project., Natural Areas Journal 11: 143-147

Gleason, Henry A.; Cronquist, Arthur (1991) Manual of vascular plants of northeastern United States and adjacent Canada, In: (Eds.) . , Bronx, New York. Pp.

Godfrey, R. K.; Wooten, Jean W. (1981) Aquatic and Wetland Plants of the Southeastern United States: Dicotyledones, , Athens. Pp.

Harvill, A. M., Jr.; Bradley, T. R.; Stevens, C. E.; Weiboldt, T.F.; Ware, D.E.; Ogle, D. W. (1986) Atlas of the Virginia Flora, , Farmville, VA. Pp.

Harvill, A. M.; Bradley, Ted R.; Stevens, Charles E.; Wieboldt, Thomas F.; Ware, Donna M. E.; Ogle, Douglas W.; Ramsey, Gwynn W.; Fleming, Gary P. (1992) Atlas of the Virginia Flora, , Burkeville, VA. Pp.

Hotchkiss, Neil (1972) Common Marsh, Underwater, and Floating-Leaved Plants of the United States and Canada, , New York. Pp.

Julien, M. H.; Broadbent, J. E. (1980) The biology of Australian weeds (Mart.) Griseb. 3. Alternanthera philoxeroides, The Journal of the Australian Institute of Agricultural Science 46: 150-155

Julien, Michael H.; Skarratt, B.; Maywald, G. F. (1995) Potential geographical distribution of Alligator Weed and its biological control by Agasicles hygrophila, Journal of Aquatic Plant Management 33: 55-60

Massey, A. B. (1957) Alternanthera in Virginia, Rhodora 59: 239

Penfound, William T. (1940) The biology of Achyranthes philoxeroides (Mart.) Standley, American Midland Naturalist 24: 248-252

Rejmankova, Eliska (1992) Ecology of creeping macrophytes with special reference to Ludwigia peploides (H. B. K.) Raven, Aquatic Botany 43: 283-299

Resource Management Inc. (1993) National list of plant species that occur in wetlands., , Minneapolis.. Pp.

Silberhorne, Eugene (December 1995) Introduced plants in the Chesapeake Bay region, telephone conversation;, , Gloucester Point VA. Pp.

1999 Invasive Alien Plant Species of Virginia. http://www.state.va.us/~dcr/dnh/invlist.htm

Ware, Donna (January 1996) Introduced plants in the Chesapeake Bay region, telephone conversation, , Williamsburg VA. Pp.

Weldon, L. W.; Blackburn, R. D.; Harrison, D. S. (1969) Common aquatic weeds., , Washington, D.C.. Pp.


Direct questions and comments to chesnemo@si.edu.

©