Officials issue Poison Hemlock warning

Posted at 1:17 PM, Jun 28, 2016
and last updated 2016-06-28 15:17:31-04

State noxious weed officials are warning Idahoans to be on the lookout for poison hemlock -- a dangerous noxious weed that can be fatal to all livestock. The hemlock is typically seen in full growth around Idaho during this time of year. 

“Poison Hemlock can kill a horse or a cow within hours of them eating it. There are even documented cases where people have died from eating poison hemlock because they mistook the weed for some type of wild herb such as parsley, dill or fennel,” said Idaho Weed Awareness Campaign spokesman Roger Batt.

Poison Hemlock grows 3 to 6 feet tall with a smooth green stem, usually spotted or streaked, with purple spots. The leaves are finely divided and lacy, resembling a “carrot-like” leaf. The weed has flowers that are small, white and clustered and resemble the spokes of an umbrella, Batt said.

The Poison Hemlock root is fleshy and white and is the most toxic part of the plant.  When crushed, Poison Hemlock leaves and roots emit a rank, unpleasant odor often compared to that of a mouse or parsnip, he added. 

“Though highly toxic, Poison Hemlock is very easy to control and eradicate with hand pulling and the use of broadleaf herbicide treatments,” Batt explained. However, he warned people should always wear rubber gloves and protective clothing/gear when pulling the weed. They should also place the plant into a plastic bag and dispose of it in a trash receptacle.

When using an herbicide labeled to control and eradicate Poison Hemlock, always follow the label and safety instructions on that label, weed officials stressed.

Poison Hemlock typically grows in wetlands, stream banks, canals, ditch banks and pastures. It’s a biennial plant -- meaning it grows for two years, flowers, seeds, and then dies. 

Pictures, audio and video footage, and other information about Poison Hemlock and how to control and eradicate it are available at the Idaho Weed Awareness Campaign’s website at:

Landowners (whether federal, state, or private) need to be aware that Idaho law requires them to control noxious weeds on their lands.  One of the best ways to control noxious weeds such as Poison Hemlock is to learn how to identify them on the lands they own. 

“If you as a landowner or recreationalist are uncertain about whether you have Poison Hemlock or other noxious weeds growing on your property, or are in need of technical expertise to identify and eradicate this and other noxious weeds, please contact your county weed superintendent’s office or look in the yellow pages for a private weed control application company,” Batt added.  

For more information about Poison Hemlock and other noxious weeds and to learn about the best ways to eradicate and control them, log on to the Idaho Weed Awareness Campaign’s website at”