Poison Hemlock
Characteristics and Dangers of Poison Hemlock
Nashville, Ark. – Poison hemlock is widely distributed throughout the United States. This weed may be spotted in pastures and along the road throughout Howard County. It may easily be mistaken for wild carrot and spotted water hemlock, which share similar characteristics because they are all in the parsley family.
Poison hemlock is a biennial plant, meaning it produces vegetative growth in the first year and flowers in the second year. The flowers of poison hemlock form an umbel shape, originating from the center of the stem and extending outwards with clusters of small white flowers at the end of each stalk. Poison hemlock seedlings will have purplish stems. Very young plants will have hairs on the stems, but as they grow, the stems of newer leaves will be waxy with no hairs. These new stems will either be purplish or have purple spots. The leaves of poison hemlock are divided and may be described as fernlike. It is important that you use more than one characteristic to distinguish this plant from its relatives. Plants of the same species may look different based on their environment.
Poison hemlock contains neurotoxins. This not only affects livestock, but humans may be at risk, too. Symptoms usually appear within a few minutes. They include convulsions, loss of coordination, respiratory distress, slowed heart rate, nausea, vomiting and death. The greatest risk of poisoning comes from ingesting the plant, but there are reports of skin irritation and respiratory reactions from touching or smelling the plant. For cattle, consuming as little as 300 grams of this weed can be poisonous.
There are several herbicide options for control of poison hemlock. Spraying poison hemlock may make the plant more desirable for livestock. To prevent consumption, rotate your animals to a different pasture for a few weeks. Multiple applications may be required.
For more information about poison hemlock, you can contact the Howard County Extension office at 870-845-7517 or visit our website at www.uaex.uada.edu. The Cooperative Extension Service is part of the University of Arkansas System Division of Agriculture.
By Dawson Bailey
County Extension Agent - Agriculture
The Cooperative Extension Service
U of A System Division of Agriculture
Media Contact: Dawson Bailey
County Extension Agent - Agriculture
U of A Division of Agriculture
Cooperative Extension Service
421 N. Main Nashville AR 71852
(870) 845-7517
dbailey@uada.edu
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