Poison Hemlock

(Conium maculatum)

 

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© Richard Old

Poison hemlock (Conium maculatum) is an erect biennial weed that is native to Europe. The plant typically grows 4 to 8 feet tall and has smooth, hallow stems that are rigid and have distinct purple spots. The plant has shiny green leaves that are pinnately compound, multi-stemmed and have a fern like appearance. The leaves are lacy, resembling parsley and have a musty odor when crushed. The first year the plant usually forms a large rosette. The second year the plant bolts a large stem, flowers and then dies. The flowers have 5 petals, clawed, notched (1 to 1.5 mm long) and are white, umbrella-like clusters at the end of the branch. They appear from June to July. The fruit matures in August-September and is flat, small and grayish-green in color.

Poison hemlock Factsheet pdf file