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Alligator weed

Thu, 05/03/2007 - 5:27pm — beth56
Alternanthera philoxeroides -- Center for Aquatic and Invasive Plants

Alternanthera philoxeroides

Non-Native to Florida


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Alternanthera philoxeroides Alternanthera philoxeroides Alternanthera philoxeroides Alternanthera philoxeroides Alternanthera philoxeroides

 

    Alligator weed is an emersed plant. It can grow in a variety of habitats, including dry land, but is usually found in water. It may form sprawling mats over the water or along shorelines.

    Appearance: Sprawling herb, usually in water, often in row crops and gardens. Stems pinkish, can become hollow when larger, to 1 m (3.3 ft) long. 

    Leaves: Opposite, narrowly elliptic or spatulate, to 9 cm
    (3.5 in) long; occasionally a few indistinct teeth on margin.

    Flowers: Reduced, bisexual in round white heads on long stalks from upper leaf axils; each flower with 4–5 thin, papery bracts, 5 stamens, 1 pistil.

    Fruit: Tiny, one-seeded, thin-walled.

    Ecological threat: FLEPPC Category II – Invasive exotics that have increased in abundance or frequency but have not yet altered Florida plant communities to the extent shown by Category I species.

    Distribution: NW, NE, C, SW, SE

    Text from Invasive and Non-Native Plants You Should Know, Recognition Cards, by A. Richard and V. Ramey, 2007. UF/IFAS Center for Aquatic and Invasive Plants, Publ. No. SP 431.

    Download the Recognition Card (PDF 512 KB).

    Biological control insects of alligator weed

    The UF/IFAS Assessment lists plants according to their invasive status in Florida.

    Alternanthera philoxeroides View the herbarium specimen image of the UNIVERSITY OF FLORIDA HERBARIUM DIGITAL IMAGING PROJECTS.