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Taxonomy

Domain	Eukarya
Kingdom	Plantae
Phylum	Magnoliophyta
Class	Magnoliopsida
Superorder	Asteranae
Order	Apiales
Family	Apiaceae
Genus	Cicuta
Species	Cicuta maculata

Scientific Name

Cicuta maculata var. angustifolia

Common Name

spotted water hemlock

Water Hemlock (Cicuta maculata)

Compiled by Joe Julian Colorado State University, Douglas County Extension, from the following sources:

Identification and Life Cycle

Water hemlock (Cicuta maculata) is a biennial and perennial in the carrot or parsnip family (Apiaciae). Other common names for water hemlock include poison parsnip, spotted cowbane, spotted water hemlock, and spotted parsley. Stems are 3 to 6 feet tall, hollow, and have purple stripes or spots. Stems are often branched and emerge from fibrous to fleshy roots. Roots are thick and tuberous and contain many small chambers. These chambers contain a brown to straw-colored liquid that is released when the roots are broken or cut. Leaves are alternate with the lower leaves pinnately to bipinnately divided. Leaves are up to 1.5 inches long and 0.75 inches across with serrated edges with the uppermost leaves not dissected. Leaf veins end at the bottom of leaf serrations rather than at the tips as in poison hemlock. Flowers are white and borne in compound flat-topped umbles at the ends of the stems and branches. Umbles can reach 6 inches across. Fruits are ovoid, prominently ribbed, two parted, and small. Water hemlock is often confused with the edible water parsnip, but can be distinguished by the distinctive roots system.

Habitats

Water hemlock is found along stream banks, irrigation canals, and roadside ditches. It can also be found in tilled areas, wet pastures, moist open woodlands, swamps, marshes, and seeps. Water hemlock is most commonly found in deep loam, clay loam, or clay soils.

Impacts

All parts of the plant contain a very poisonous alkaloid and resinoid particularly when plants are young and actively growing. Concentrations are highest in the roots. The toxin is a convulsant that can lead to death through respiratory failure. Livestock and humans are particularly susceptible.

Biology and Ecology

Water hemlock reproduces by seeds. In the first year, the plant produces a small seedling that can resemble wild carrot or water parsnip. Plants usually bolt in the second year producing flowers. Flowers bloom from June to September.

Management Approaches

Preventing the increase of water hemlock population by controlling seed set, is a management priority.

Biological Control

There are no commercial biological control methods available for water hemlock.

Mechanical and Cultural Control

Hand grubbing can be effective at containing small populations of water hemlock. It is important to remove the entire root as roots are attractive to livestock. Grubbing is easiest when the soil is moist.

Chemical Control

Chemical control is most effective when done in late spring or early summer. There is some evidence that toxicity of water hemlock increases after spraying until the plant dies. Therefore it is advised that animals be kept away from treated plants for three weeks after spraying.

Examples of herbicides that can be used to manage water hemlock

Consult herbicide labels for additional rate, application, and safety information. Additional herbicide information can be found at http://www.greenbook.net.

Due to constantly changing labels, laws and regulations, the sponsors of this web site assume no liability for the suggested use of any chemicals noted in the management section. Contact your local pest management personnel for current information on labeled pesticides that can be used for the intended plant disease, insect pest or weed.

References

For more information and images please visit IPM Bugwood: http://www.ipmimages.org/search/action.cfm?q=Cicuta%20maculata

HPIPM:Water Hemlock