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Extension > Local Extension Offices > Stearns > County Horticulture Educator > Articles > All About Poison Hemlock

All About Poison Hemlock

University of Minnesota Extension, Stearns County News
August 16, 2017        
           
Source:  Haely Leiding, Extension Intern
University of Minnesota Extension
Stearns, Benton, & Morrison Counties

 

All About Poison Hemlock
By Haely Leiding, University of Minnesota Extension

ST. CLOUD, Minn. (08/16/17) - This summer a topic of discussion throughout the state has been poison hemlock. This is an invasive plant that is native to Europe and North Africa. It is highly toxic to humans and livestock, and if ingested it may result in death.

Poison hemlock thrives in places that receive generous amounts of sunlight and can be found near railways, ditches, edges of fields, pastures, around farms, and paths. Livestock poisoning can happen when there is a presence of poison hemlock in hay, pastures that have been overgrazed or when other sources of feed have run out.

Poison hemlock is known as a biennial plant which means that it is a flowering plant that takes two years to fully grow. The first year, poison hemlock grows leaves, stems and roots. Poison hemlock has leaves that are triangular in shape, dark green in color, lacy and fern like. The stem of the plant are hollow between nodes, ridged, and hairless with purple spots throughout. The second year the plant grows to be around 4-6 feet. Flowers will appear the second year and are white in color with five notched petals organized in an umbrella shape.

It is highly recommended that you call a professional to handle this plant, but if you choose to manage poison hemlock yourself make sure to wear gloves, protective clothes covering all of your skin, and protective eyewear. Shower after removal to be sure to remove toxic sap and always launder your clothing. Plants can be sprayed with an herbicide and dug out; read and follow all application and safety instructions when using herbicides. Make sure to ensure that no flowers or seed heads are left behind.

To dispose of plants bury the plants, flowers and seed heads in a plastic bag in an area that will remain undisturbed. To learn more about management visit the University of Minnesota- Extension website at z.umn.edu/poisonhemlock.

If you think you have poison hemlock email arrest.the.pest@state.umn.us and send a picture of the purple spots on the stem, a leaf, and a specific location of the plant.

PHOTO:  Poison hemlock. Clockwise from left: lacy, triangular leaves; white flowers in umbel; green stem with purple spots and blotches; seeds.  Image courtesy K.-Chayka. http://www.myminnesotawoods.umn.edu/poisonhemlock/

Contacts

Beth Berlin
Extension Educator, Horticulture
(320) 255-6169
adam0062@umn.edu
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