• Poison-hemlock Plant Mature 215x150

Category C Weed

Parsley family (Apiaceae)

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Poison-hemlock (Conium maculatum)


    • Up to 10 ft. tall, green with purple spots, stout, hollow except at nodes and highly branched with lengthwise ridges


      • Triangular, 4-12 in. long, finely pinnate-divided (fern-like) and lack hair (glabrous); leaflets have toothed edges; foliage has a musty odor


        • Small and white; arranged in umbrella-like clusters at end of a stalk


          • Thick, deep taproot


            • Grows best in moist sites; often infests crop fields, waterways, roadsides and waste areas; known to occur in all Nevada counties EXCEPT Clark, Lander, Mineral, Nye and Pershing

            • Biennial; reproduces by seed

            • Highly toxic to animals and humans when consumed


              • Repeated mowing or tillage prior to seed production is effective; hand-removal by cutting the taproot below the crown can also eliminate plants (avoid contact with skin)

              • An insect biological control agent is available

              • Apply 2,4-D, MCPA, glyphosate, chlorsulfuron or metsulfuron to young actively growing plants