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.
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.
Opposite, narrowly elliptic or spatulate, to 9 cm (3.5 in) long; occasionally a few indistinct teeth on margin.
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.
Tiny, one-seeded, thin-walled.
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.
NW, NE, C, SW, SE
Biological control insects of alligator weed
- Alligatorweed flea beetle Agasicles hygrophila Selman and Vogt (Coleoptera: Chrysomelidae: Halticinae) by Ted D. Center, James P. Cuda, Michael J. Grodowitz EENY 462 (2009)
- Alligatorweed thrips (suggested) Amynothrips andersoni ONeill (Insecta:Thysanoptera:Phlaeothripidae) by Ted D. Center, James P. Cuda, and Michael J. Grodowitz. EENY 476/IN 859 (2010)
For brief control information, see Efficacy of Herbicide Active Ingredients Against Aquatic Weeds by K. Langeland, M. Netherland, and W. Haller.