Poison-hemlock identification and control: Conium.
Poison hemlock, a Class B noxious weed, is found in open sunny areas, fields, vacant lots, and on roadsides.People, livestock, and wildlife can be killed by eating a small amount of this plant.
The stems of poison-hemlock are not hairy and are hollow.The leaves are bright green, fern-like, finely divided, and have a strong musty odor when crushed.There are small, umbrella-shaped clusters on the ends of branched stems.
Poison-hemlock can grow throughout the year.Plants that are first year can survive in mild climates.The lack of hairs on the stems of poison-hemlock plants can be seen as a sign that the plant is young.
Second-year plants produce many umbrella-shaped clusters of tiny, white, 5-petaled flowers in late spring.The flowering poison-hemlock is confused with the wild carrot.In contrast to poison-hemlock, wild carrot has one densely packed umbrella-shaped flower cluster on a narrow, hairy stem, usually with one purple flower in the center, and is usually 3 feet tall or less.The carrot flowers later in the summer.
Symptoms of poison-hemlock appear 20 minutes to three hours after ingestion.The dead canes of the plant are toxic for up to three years.In sunny areas, the amount of toxin tends to be higher.The main danger is eating the plant, but it is also toxic to the skin and respiratory system.When controlling poison-hemlock, wear gloves and take breaks when pulling or mowing large amounts of plants.A person had a severe reaction after pulling plants on a hot day.
The typical symptoms for humans include dizziness and trembling, followed by a slow heartbeat, paralysis of the central nervous system, and death due to respiratory failure.Symptoms for animals include nervous trembling, salivation, lack of coordination, pupil dilation, rapid weak pulse, respiratory paralysis, coma, and sometimes death.For both people and animals, quick treatment can reverse the harm.If you suspect poisoning from this plant, you should call for help immediately because the toxins are fast-acting for people and animals.
The King County Noxious Weed Control Board selects Poison-hemlock for required control on public lands and public rights-of-way.Control of poison-hemlock is not required on private property in King County.See the Noxious weed lists and laws for more information.
The King County Noxious Weed Control Board encourages property owners to remove poison-hemlock where possible to avoid introducing it to new landscapes.
If you find poison-hemlock, please report it to the property owner or residents on our Report-a-Weed form.Control of poison-hemlock is not required of private property owners in King County.If you notice poison-hemlock at any place where people are growing food or collecting wild plants, please notify the property manager or agency in charge as soon as possible, or report the location to us and we will alert them.This is important in p-patch or community gardens where new gardeners may not be familiar with this plant.We can help if you don't know who to contact.