Hygrophila polysperma

Common Name: Indian swampweed

Family: Acanthaceae

Common Synonyms: Justicia polysperma

USDA Hardiness Zone: 7b - 11

Growth Habit: Emergent Aquatic

Origin: India, Malaysia

FISC Category: 1

FDACS Listed Noxious Weed: Yes

Introduction Date: 1965

IFAS Assessment:

• North: PROHIBITED
• Central: PROHIBITED
• South: PROHIBITED

Description

Perennial aquatic, mostly submersed, rooted. Square stem. Leaves opposite, variable color green to reddish, 8 cm long and 2 cm wide, broadest toward tip, joined at node by ciliate flange of tissue to 1.5 mm long. Flowers bluish white, small, solitary in upper leaf axils (almost hidden by the leaves). Fruit a narrow capsule with tiny round seeds.

Habitat

Streams, springs, lakes, and ruderal sites, prefers flowing streams

Comments

Popular aquarium plant. Vouchered Broward north to Leon County. Established in some waterways since 1980s. Eradication unlikely.

Control Methods

• Manual:
• Chemical: Flumioxazin most effective, frequent applications of various formulations. Copper, diquat, endothall, fluridone and 2,4-D provide marginal control. [IFAS: https://plants.ifas.ufl.edu/manage/why-manage-plants/floridas-most-invasive-plants/hygrophila/]
• Biological: Triploid grass carp (successful in canals)

Control Notes

**Follow herbicide labels: Only herbicides registered for application in water by EPA and FDACS may be applied to weeds growing in or near water.

References

Dave's Garden. 2013. PlantFiles: Hygrophila, Hygrophila polysperma. http://davesgarden.com/guides/pf/go/32039/. Accessed on December 10, 2013.

IFAS, Center for Aquatic and Invasive Plants. 2013. East Indian hygrophila.http://plants.ifas.ufl.edu/node/191. Accessed on December 2, 2013.

Langeland, K.A., H.M. Cherry, C.M. McCormick, K.C. Burks. 2008. Identification and Biology of Non-Native Plants in Florida's Natural Areas-Second Edition. IFAS Publication SP 257. University of Florida, Gainesville, Florida.

Vandiver VV. 1980. Hygrophila. Aquatics 2:4-11