Identification
This native rhizomatous perennial is found in moist areas such as marshes, roadside ditches, and other wetlands. Growing up to 6 feet tall, stems (B) are hollow and has alternate compound leaves comprised of 2-3 lance-shaped leaflets with serrate edges (C). Blooming from May-September, its flowers are compound umbels of small, 5-petaled white flowers. According to USDA, this plant is considered the most toxic plant in North America.
Uncommon in Child’s Hollow in disturbed area near the Missouri River and in disturbed sites in the Wetlands. Locally common along moist roadsides.
Often mistaken for wild parsnip (Pastinaca sativa) or poison hemlock (Conium maculatum). Wild parsnip has similar flowers, however they are yellow instead of white. Poison hemlock can be distinguished from water hemlock by its purple spotted stem and fern-like leaves. Poison hemlock is also toxic if ingested, and wild parsnip causes severe skin rashes and blisters when skin is exposed to sap in the presence of sunlight.
According to USDA, water hemlock is considered the most toxic plant in North America. The toxins can pass through the skin, leading to accidental poisoning when handling the plant without proper protection.
All photos courtesy of Drew Granville