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Science and Environment

Be On The Lookout For Poison Hemlock In Indiana

(Jerry Kirkhart/Flickr)
You can tell poison hemlock apart from things like Queen Anne's lace and wild parsnip by the specks of purple on it's hairless stem when it's in its second year.

While poison hemlock has been in the state for years, the deadly invasive plant is moving into more urban areas. That’s a problem because it can be fatal to people, pets and livestock.

Eating any part of poison hemlock can be deadly and touching the plant can irritate your skin. Dugan Julian is a regional specialist with Southern Indiana Cooperative Invasive Species Management. He said it’s easy to mistake the plant for a wild carrot or parsnip.

“Where a lot of the accidental ingestions come from with poison hemlock are foragers who think they found a parsnip and they consume it and a lot of bad stuff happens," Julian said.

Julian said the weather we’ve been having — coupled with disturbed ground from agriculture and construction — has made the right environment for poison hemlock to spread. He said over time it’s moved into new areas where people are more likely to encounter it. 

“This plant that used to be found in hay lots and field edges and agricultural drainage ditches — all of a sudden, it's making its way into the suburbs and even to the urban areas along roadsides there," Julian said.

According to EDD Maps — an invasive species mapping system — Indiana is one of the few states where poison hemlock is found in all counties.

While mowing over the plant can help control it, Julian said you don't want to mow it or harvest fields that have the plant after it has flowered — which spreads its seeds.

A poison hemlock plant lives for two years. In the first year, it looks like a fern growing low to the ground. In the second year, it’s a tall plant with clumps of white flowers with a hairless stem that has flecks of purple.

Julian said the most effective way to control poison hemlock is to mow it when it’s not flowering combined with an herbicide. However, you need to be very careful to make sure you’re using the right herbicide for your situation — especially if the poison hemlock is by a waterway. Contact the Office of Indiana State Chemist for recommendations.

If you find poison hemlock, you can report it through EDD Maps or to the Indiana Department of Natural Resources.

Contact reporter Rebecca at rthiele@iu.edu or follow her on Twitter at @beckythiele.

Indiana Environmental reporting is supported by the Environmental Resilience Institute, an Indiana University Grand Challenge project developing Indiana-specific projections and informed responses to problems of environmental change.