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Federal Noxious Weed
TDA Noxious Weed
TPWD Prohibited Exotic Species
Invasive Plant Atlas of the US

NOTE: means species is on that list.

Conium maculatum


Poison hemlock

Synonym(s):
Family: Apiaceae (Carrot Family)
Duration and Habit: Biennial Herb


Photographer: Eric Coombs
Source: Oregon Department of Agriculture, Bugwood.org

Description

Erect, biennial, up to 8' tall forb; stems green with purple spots, freely branched, and hollow; all parts deadly poisonous. Flower is white, 5-parted; inflorescence of many 2"-3 1/2" mostly terminal umbels often with 2-4 together from the top stem node, with age the side umbels overtop the central one; blooms June-Aug.

Ecological Threat: All plant parts are poisonous; however, the seeds contain the highest concentration of poison. (It was probably used to poison Socrates.) It contains highly poisonous alkaloids toxic to all classes of livestock and humans. Human deaths have occurred from harvesting and consuming the roots as wild carrots or parsnips. It may act as a pioneer species quickly colonizing disturbed sites and displacing natives during early successional areas.

Biology & Spread:

History: Poison hemlock is native to Europe and was introduced into North America in the 1800s as an ornamental.

U.S. Habitat: Waste places, weedy areas, and woodland borders.

Distribution

U.S. Nativity: Introduced to U.S.

Native Origin: Europe (Bailey, L.H. and E.Z. Bailey, Hortus Third: A Concise Dictionary of Plants Cultivated in the United States and Canada, MacMillan Publishing Co., Inc., New York , (1977).); NatureServe Explorer

U.S. Present: AL, AR, AZ, CA, CO, CT, DE, GA, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VA, VT, WA, WI, WV, WY

Distribution: British Columbia to Nova Scotia and south throughout most of the United States; not reported in Florida and Mississippi.

Mapping

Invaders of Texas Map: Conium maculatum
EDDMapS: Conium maculatum
USDA Plants Texas County Map: Conium maculatum

Invaders of Texas Observations

List All Observations of Conium maculatum reported by Citizen Scientists

Resembles/Alternatives

Management

USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS. MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.

Text References

USDA, NRCS. 2001. The PLANTS Database, Version 3.1, National Plant Data Center, Baton Rouge, LA 70874-4490 USA. - http://plants.usda.gov/

USDA Forest Service, Forest Health Staff, Newtown Square, PA. Invasive Plants website: http://www.na.fs.fed.us/fhp/invasive_plants.

Online Resources

Search Online

Google Search: Conium maculatum
Google Images: Conium maculatum
NatureServe Explorer: Conium maculatum
USDA Plants: Conium maculatum
Invasive Plant Atlas of the United States: Conium maculatum
Bugwood Network Images: Conium maculatum

Last Updated: 2008-11-24 by LBJWFC
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