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 Carson City, Douglas, Elko, Lander, Lincoln, Lyon, Nye, Storey, Washoe, and White Pine counties
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, chlorsulfuron, glyphosate, metsulfuron or triclopyr to actively growing young plants; aminopyralid, imazapic, or imazapyr preemergence or on young plants

Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Nevada Noxious Weed Field Guide – Poison-hemlock, Extension, University of Nevada, Reno, Field Guide

Extension Associated Contacts

Heidi Kratsch

Also of Interest:


Managing Poison and Western Water Hemlocks This fact sheet contains several ways to manage poison and western water hemlocks by taking a look at the habitat, impact, identification, and weed management options. Graham, J. and Johnson, W. 2004, Extension \| University of Nevada, Reno, FS-04-09

Associated Programs

Master Gardeners of Nevada

Program trains local gardeners to provide research-based horticulture information to Nevadans

Grow Your Own, Nevada!

Learn the secrets of high desert gardening

Green Industry Training

A workforce development program to train green industry professionals, who receive continuing education units for pesticide applicator, ISA-certified arborist and Qualified Water Efficient Landscaper

Nevada Noxious Weed Field Guide – Poison-hemlock