What is Hydrilla?

A close up of a hand holding water weeds

Hydrilla (Hydrilla verticillata) is a submerged aquatic invasive plant that looks similar to the native American waterweed (Elodea canadensis) and also appears similar to another aquatic  invasive plant, Brazilian elodea (Egeria densa). Hydrilla has visibly serrated leaves that grow in whorls of four to eight, and small white flowers that bloom at the surface on slender stalks. Hydrilla can grow in water depths of 30 feet. Of all aquatic invasive species, Hydrilla causes some of the most challenging problems. The plant grows into dense, rooted stands, and also may be found as large drifting mats of live plant fragments. Hydrilla impacts fish habitat, clogs intake pipes, and makes recreational swimming and boating difficult.

How do we stop it?

Clean, Drain, and Dry: Always clean, drain, and dry your boat, paddle gear, and footwear after use. This prevents the transfer of organisms between water bodies.

  • Clean all plant stems and fragments and mud from boats and trailers before leaving your lake or river and dispose of them in an aquatic invasive species disposal station if one is available.
  • Empty all water from your gear well before moving to a new body of water.
  • Dispose of leftover bait in the trash, not in the water.
  • Clean out waders and wading boots before moving to a new body of water.
  • Dry your boat and gear thoroughly between water bodies by towel drying or drying in the sun for at least 5 days.

Read more about Clean, Drain, and Dry requirements and best practices at the following websites:

Northern Forest Canoe Trail
Lake Champlain Basin Program

If You See It, Report It

You can report invasive species sightings through the iMapInvasives website, the iMapInvasives mobile app, or by contacting the Adirondack Park Invasive Plant Program (APIPP).

Volunteer with ADK

You can help ADK survey ponds and lakes for aquatic invasive species such as Yellow Floating Heart, European frog-bit, European Water Chestnut, and Curly Leaf Pond Weed. For more information on the Backcountry Water Monitors Project and upcoming workshops and outings, please visit our website.


Learn More About Hydrilla (sources for description above)




Please also see all invasive species of concern for the Adirondack Park: http://adkinvasives.com/species_of_concern/