Poison Hemlock
Poison-hemlock stems have reddish or purple spots and streaks, are not hairy, and are hollow. Leaves are bright green, fern-like, finely divided, toothed on edges and have a strong musty odor when crushed. Flowers are tiny, white and arranged in small, umbrella-shaped clusters on ends of branched stems.
Poison-hemlock is a biennial and germinates throughout the year. First year plants are low-growing and may overwinter in mild climates. Young poison-hemlock plants somewhat resemble carrot plants, but can be distinguished by the lack of hairs on the stems and the purple-reddish blotches on the stems.
In late spring, second-year plants reach 6-10 feet tall and produce numerous umbrella-shaped clusters of tiny, white, 5-petaled flowers. Flowering poison-hemlock may be confused with wild carrot (Daucus carota, or Queen Anne's Lace). In contrast with poison-hemlock, wild carrot has one densely packed umbrella-shaped flower cluster on a narrow, hairy stem, usually with one purple flower in the center of the flower cluster, and is usually 3 feet tall or less. Wild carrot also flowers later in the summer.
Toxicity
Poison-hemlock is acutely toxic to people and animals, with symptoms appearing 20 minutes to three hours after ingestion. All parts of the plant are poisonous and even the dead canes remain toxic for up to three years. The amount of toxin varies and tends to be higher in sunny areas. Eating the plant is the main danger, but it is also toxic to the skin and respiratory system. When controlling poison-hemlock, minimize exposure by wearing gloves and taking frequent breaks when pulling or mowing large amounts of plants. One individual had a severe reaction after pulling plants on a hot day because the toxins were absorbed into her skin.
The typical symptoms for humans include dilation of the pupils, dizziness, and trembling followed by slowing of the heartbeat, paralysis of the central nervous system, muscle paralysis, and death due to respiratory failure. For animals, symptoms include nervous trembling, salivation, lack of coordination, pupil dilation, rapid weak pulse, respiratory paralysis, coma, and sometimes death. For both people and animals, quick treatment can reverse the harm and typically there aren’t noticeable aftereffects. If you suspect poisoning from this plant, call for help immediately because the toxins are fast-acting – for people, call 911 or poison-control at 1-800-222-1222 or for animals, call your veterinarian.