Invasive Plants of Wisconsin

Conium maculatum L.
poison-hemlock poisonous plant
Family: Apiaceae
plant plants stem leaf leaf sheath flowers
plant plants stem leaf leaf sheath flowers

Conium maculatum is a large plant, commonly exceeding 6 (-8) feet in height, with large, hollow, purple-spotted green stems, and numerous small white flowers. All parts of the plant are poisonous and potentially fatal if ingested. Leaves are broadly triangular and multiply-divided and are attached to the stem by conspicuous sheathing bases. It is a member of the carrot or parsley family, Apiaceae, and there are many species in this family in Wisconsin, so extreme care should be taken to ensure that a given plant has been correctly identified.

Distribution shown in the accompanying map is based only on verified voucher specimens and the true range is undoubtedly larger, especially in the southern portion of the state. Most locations in our area are on disturbed soils near roads or other areas of heavy human modifications, but it could occur in just about any sunny site.

known Wisconsin distribution


Contact the author