SIOUX FALLS, S.D. (KELO) — Poison Hemlock is a flowering biennial plant, and a hazardous invasive species. The plant has its origins in Europe and according to the U.S. Forest Service is highly toxic, especially for children.
In 2016, the South Dakota Department of Agriculture (now the Department of Agriculture and Natural Resources – DANR) reported that Poison Hemlock had been detected in three South Dakota counties; Codington, Deuel and Hamlin.
In Codington and Hamlin counties, the state determined (based on reports from County Weed Boards) that there were fewer than 100 acres infested with Poison Hemlock. Deuel county meanwhile was listed as having 1,001-5,000 infested acres.
The DANR distribution map for 2020 shows that reports of the deadly plant have spread. Codington, Deuel and Hamlin counties are still listed, but four more; Grant, Clark, Kingsbury and Butte counties have been added.
In Grant and Clark counties, the state listed 2020 distribution at less than 200 acres infested. In Codington, Hamlin and Kingsbury counties, spread is listed at 101-500 acres infested.
Butte County, on the other side of the state, is listed as having 501-1,000 infested acres, while Deuel County is reporting an in infestation of 5,001-10,000 acres.
KELOLAND News reached out to the Deuel County Weed Supervisor, but have not received a response.
Jessalyn Bachler, an SDSU Extension Range Field Specialist says that the spread of Poison Hemlock in the state extends beyond the reported counties. “Where I’ve seen it is primarily in the [Black Hills] counties; Lawrence, Pennington and Custer, and I think it’s starting to spread out of the Hills and become more of a concern,” she said.
Bachler’s reports of Hemlock in the Black Hills are backed up by EEDMapS.org, a website used by the Minnesota Dept. of Natural Resources (DNR) to allow residents to report sightings of noxious weeds. According to their data, Poison Hemlock has also been reported in Harding, Pennington, Custer, Todd, Tripp, Gregory and Clay Counties.
Bachler says Poison Hemlock follows infrastructure, growing in area where the soil has been disturbed. “It like disturbance,” she said “in those wetland ditch areas, and a lot of our smaller acreages in and around the Hills that aren’t necessarily managed by grazing or mowing — it probably is going to start to pop up in some of those disturbed areas.”
These disturbed areas, according to an extension report authored by Bachler and Krista Ehlert, include livestock pens and manure piles, cultivated fields and gardens, ditches and fence lines or wet areas that dry up in late summer.
“It is highly dangerous and poisonous,” said Bachler, describing the aptly named Poison Hemlock. “All parts of the plant are highly poisonous to humans and livestock.”
Bachler says that if you suspect you have Hemlock on your property, it’s important to get confirmation and recommends contacting your local county weed supervisor.
In terms of recognizing the plant, Bachler says the leaves resemble little parsley leaves. The plant’s flowers form a white umbel and resembles the plant Queen Anne’s Lace or wild carrot. Bachler compared the flowers to a white version of the dill plant. “The stem is also spotted with purple,” she said. You can take a look at the plant in Bachler’s report here, or at the USFS site here.