• Hydrilla Plant 215x150

Category A Weed

Waterweed family (Hydrocharitaceae)

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Hydrilla (Hydrilla verticillata)


    • Aquatic weed up to 25 ft. long, submersed, slender and branched near water surface


      • Strap-like (linear) to lance-shaped, 0.25-0.75 in. long and less than 0.2 in. wide; NO leaf stems (petioles); arranged in whorls of 4-8 around stem; edges (margins) are toothed; midvein on leaf underside often has one or more sharp teeth


        • Small, white, attached to threadlike stalks up to 4 in. long and float on water surface


          • Unbranched, slender and white; yellowish, potato-like tubers (0.25-0.5 in. diameter) form at root tips


            • Often found in still or slow-moving water; not known to occur in Nevada

            • Perennial; reproduces by stem fragments and tubers; occasionally produces turions at leaf axils; turions are mostly cylindrical, dark green reproductive structures up to 0.5 in. long

            • Listed on the Federal Noxious Weed List


              • Mechanical removal can be effective but must be done repeatedly; escaped stem fragments can form new plants

              • Grass carp can be an effective biological control

              • Aquatic herbicides such as diquat, endothall, fluridone and copper complexes are effective