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
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 Survival | For 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.