Eurasian watermilfoil (Myriophyllum spicatum)

Category A Weed

Watermilfoil family (Halorgaceae)

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  • Aquatic weed up to 12 ft. long, submersed, branched near water surface, growing points often reddish; breaks into fragments easily


    • Whorled with 4 leaves per node; leaves are green to brown, less than 1.25 in. long and pinnately-divided with more than 14 pairs of narrow, opposite lobes (less than 0.4 in. long)


      • Pinkish and small, each with a small, bract-like leaf

      • Occur in clusters on small, pencil-like stalks that emerge from water (1-3 in. long); stem often bends to become parallel with the water surface after flowering


        • Creeping rhizomes


          • Most common in still or slow-moving water but can sometimes be found in fast-moving rivers, streams and irrigation ditches; known to occur in Churchill, Douglas Washoe and White Pine counties

          • Perennial; reproduces by rhizomes, stem fragments and seed


            • Mechanical removal can be effective but must be done repeatedly; escaped stem fragments can form new plants; draining then allowing an empty water-body to freeze can be effective

            • Aquatic herbicides such as 2,4-D, diquat, endothall, triclopyr, fluridone and copper complexes are effective


              Eurasian Watermilfoil mature plant
              Mature Plant
              Eurasian Watermilfoil Infestation
              Eurasian Watermilfoil Flower
              Eurasian Watermilfoil Seed Pod
                Nevada Noxious Weed Field Guide
              Nevada Noxious Weed Guide