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

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

Learn more about the author(s)

Carrie Jensen

Heidi Kratsch

Also of Interest:


Nevada Native Plant Nurseries and Seed Suppliers Here's our comprehensive list of native plant nurseries and seed suppliers for Nevada. Jensen, C. 2025, Extension, University of Nevada, Reno
Know Nevada Insects: Monarch Butterfly The monarch butterfly is perhaps one of the most iconic butterfly species in North America, and it can be found throughout Nevada in the summertime. Learn about Monarch lifecycle, catepillar host plants and damage, threats and conservation and resources. Burls, K., Newton, J. 2017, Extension \| University of Nevada, Reno, FS-17-13
Know Nevada Insects: Orange sulphur butterfly - Colias eurytheme (Boisduval) The collective research on the description and life cycle of orange sulphur butterfly. Including the damages done by caterpillars and integrated pest management as a result of it. Burls, K. and Newton, J. 2017, University of Nevada Cooperative Extension, Fact Sheet 17-15
Kids Know Nevada Insects: Monarch Butterfly I am the monarch butterfly! I am found all throughout the United States and even southern Canada. I am most well-known for the yearly trip back and forth (called a migration) that I make every fall and spring. Monarchs in Nevada and other western states head to the coast of Calif... Burls, K., Newton, J. 2015, Extension \| University of Nevada, Reno, IP
Know Nevada Insects: Orange Sulphur Butterfly I am the orange sulphur butterfly! I can be found in all of the United States, except Alaska and Hawaii. I fly most of the summer, from May to October, in Nevada. Learn about my life cycle, why I'm important and what I eat. Burls, K., Newton, J. 2015, Extension \| University of Nevada, Reno, IP

Nevada Noxious Weed Field Guide – Poison-hemlock