Poison-hemlock (Conium maculatum)



  • Poison-hemlock Plant Mature 215x150

Category C Weed

Parsley family (Apiaceae)

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Stem

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

Leaves

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

Flower

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

Root

  • Thick, deep taproot

Other

  • 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

Control

  • 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

Images

Poison-hemlock Plant Mature 215x150
Mature Plant
Poison-hemlock Plant Young 215x150
Young Plant/basal
Poison-hemlock Flower 215x150
Flowers
Poison-hemlock Stem 215x150
Spotted stem
Poison-hemlock Seedling 215x150
Seedling
Nevada Noxious Weed Field Guide
Nevada Noxious Weed Guide