Poison hemlock (Conium maculatum
) is an annual or biennial herb of the Apiaceae family. It is native to Europe and western Asia but was introduced into North America in the 1800s. The plant is now widely distributed across the United States. It has small white flowers clustered in large compound umbels that are 1.5-2.5 inches wide. The stem has a hollow, erect, smooth purple-spotted stem that grows 2-10ft in height. Poison hemlock's leaves are fern-like, large and lacy, alternate and basal, with the upper leaves progressively smaller. When the leaves, stem or flowers are crushed, they produce an unpleasant, parsnip-like odor.Toxic components
Poison hemlock is highly toxic to all animal species, including humans. All parts of the plant contain several piperidine alkaloids, which when ingested, are rapidly absorbed from the gut into the bloodstream. The alkaloid initially has a stimulating effect, followed by a longer-lasting depression of nerve function.