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Alternanthera philoxeroides

Common Name: alligator weed

Family: Amaranthaceae

Common Synonyms: Achyranthes philoxeroides

USDA Hardiness Zone: 7b-11

Growth Habit: Aquatic, Forb/Herb

Origin: South America

FISC Category: 2

FDACS Listed Noxious Weed: Yes

Introduction Date: 1894

IFAS Assessment:

  • North: PROHIBITED
  • Central: PROHIBITED
  • South: PROHIBITED
Flowering plant showing typical aquatic growing conditions.
Graves Lovell, Alabama Department of Conservation and Natural Resources, Bugwood.org
A monoculture of alligatorweed growing from the shore into the shallow water.
G Buckingham, USDA Agricultural Research Service, Bugwood.org

Description

Found throughout florida, alligator weed is a trailing herb that can grow aquatically. The plant has hollow stems and will have nodes along the stalk where it is able to root. Leaves are opposite, simple, and elliptic with smooth margins. Has small white bushy flowers that are visible during the warm months of the year.

Habitat

Freshwater tidal swamp, slough, floodplain marsh, strand swamp, ponds, row crops, gardens

Comments

Spreads by dividing rhizomes, tubers, corms or bulbs, not by seed.

Map of species distribution

Control Methods

  • Manual: NA
  • Chemical: Imazapyr
  • Biological: Agasicles hygrophila (Coleoptera: Chrysomelidae: Halticinae),Amynothrips andersoni (Insecta: Thysanoptera: Phlaeothripidae), Arcola (= Vogtia) malloi (Insecta: Lepidoptera: Pyralidae) (IFAS)

Control Notes

NA

References

IFAS, Center for Aquatic and Invasive Plants. 2013. https://plants.ifas.ufl.edu/plant-directory/alternanthera-philoxeroides/. Accessed June 13, 2017.

IFAS, Assessment of Non-Native Plants in Florida's Natural Areas. https://assessment.ifas.ufl.edu/assessments/alternanthera-philoxeroides/. Accessed June 13, 2017.

Dave's Garden. PlantFiles: alligatorweed, Alternanthera philoxeroides. http://davesgarden.com/guides/pf/go/32230/#b. Accessed June 13, 2017.

IFAS. 2011. Integrated Management of Nonnative Plants in Natural Areas of Florida. http://edis.ifas.ufl.edu/pdffiles/WG/WG20900.pdf. Accessed June 13, 2017.

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