poison-hemlock USDA PLANTS Symbol: COMA2
U.S. Nativity: Exotic
Habit: Forbs/Herbs
Conium maculatum L.

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Taxonomic Rank: Magnoliopsida: Apiales: Apiaceae
Synonym(s): poison hemlock, deadly hemlock, poison parsley
Native Range: Europe (BAIL);

Conium maculatum, Poison-Hemlock is a biennial herbaceous plant in the carrot family (Apiaceae) that grows 3-8 ft. (0.9-2.4 m) tall. Stems are stout, hollow, ridged, and purple-spotted. C. maculatum has a thick, white taproot that may easily be mistaken for wild parsnips. All plant parts are poisonous; however, the seeds contain the highest concentration of poison. C. maculatum is native to Africa, temperate and tropical Asia and Europe.
Leaves are shiny green, 3-4 times pinnately compound, and clasp the stem at the swollen nodes. Crushed foliage and roots have a disagreeable, parsnip-like odor.
Flowers are small, white, and held in umbels about 3 in. (7.6 cm) across (appearing in early summer).
C. maculatum reproduces from seed. Fruits are ridged and flattened, and each fruit holds two seeds.
Ecological Threat
C. maculatum contains highly poisonous alkaloids toxic to mammals. Human deaths have occurred from harvesting and consuming the roots as wild carrots or parsnips. C. maculatum quickly colonizes disturbed habitats such as roadsides, old fields, fencerows and ditches. In natural areas it can displace native plant species and prefers riparian habitats. Many U.S states have listed C. maculatum as a noxious weed.

Identification, Biology, Control and Management Resources

Selected Images from Invasive.orgView All Images at Invasive.org

Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage

EDDMapS Distribution:
This map is incomplete and is based only on current site and county level reports made by experts and records obtained from USDA Plants Database. For more information, visit www.eddmaps.org

State(s) Where Reported invasive.
Based on state level agency and organization lists of invasive plants from WeedUS database.

U.S. National Parks where reported invasive:
Antietam National Battlefield (Maryland)
Colonial National Historical Park (Virginia)
Grand Canyon National Park (Arizona)
Harpers Ferry National Historical Park (West Virginia)
Monocacy National Battlefield Park (Maryland)
Stones River National Battlefield (Tennessee)

Invasive Listing Sources:
California Invasive Plant Council
Faith Campbell, 1998
Hoffman, R. & K. Kearns, Eds. 1997. Wisconsin manual of control recommendations for ecologically invasive plants. Wisconsin Dept. Natural Resources, Bureau of Endangered Resources. Madison, Wisconsin. 102pp.
Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
Kentucky Exotic Pest Plant Council
Mid-Atlantic Exotic Pest Plant Council, 2005
Pacific Northwest Exotic Pest Plant Council, 1998
Pennypack Ecological Restoration Trust, Pennsylvania.
Tennessee Exotic Pest Plant Council