FLIP: Florida Invasive Plants

Hydrilla verticillata

Common Name(s): Hydrilla, water thyme, Florida elodea, waterweed


Old World

Ecological Impact

Hydrilla can spread rapidly and disrupts native submersed aquatic plant communities.  In dense populations, hydrilla may cause a shift in zooplankton communities and affect water chemistry (Langeland and Burks, 1998).


A submersed aquatic plant, hydrilla can grow to the surface of waterbodies and form dense mats.  The stems are slender, up to 25 feet long and are branched.  Leaves are small and grow in whorls of 4 to 8 around the stem; with saw-toothed (serrated) leaf edges.  Flowers are tiny and white with 3 petals that grow on long stalks.

Identification Tips

Hydrilla has one or more sharp teeth along the length of the leaf mid-rib.  May be confused with another invasive non-native submersed aquatic plant, Brazilian waterweed (Egeria densa). 


Introduced to Florida in 1960 and was found to have spread to all drainage basins in the state by the 1970s (Langeland and Burks, 1998).

Florida Range

Found throughout the state of Florida. 

Prevention/Management Strategies

Do not plant or release into water gardens or natural waterways. Check watercraft propellers and trailers for plant material before and after entry into waterways. 

For more information visit the Stop Aquatic Hitchhikers website.


Most photos courtesy of the Atlas of Florida Plants; click for additional plant details.

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Florida Invasive Plants