The miniscule (4mm. wide), radially symmetrical flowers of water hemlock are arranged in dome-shaped compound umbels that measure approximately 7.5 cm in width. The flowers are bright-white, flattened, and have rounded petals.
The fruit is round and flat with thick ridges.
Water hemlock has two types of leaves. The light green, lanceolate, lower leaves are long, measuring 30 cm. in length, and pinnately forked by a deep sinus. The margins are coarsely toothed and the tips are sharply pointed. The light green, upper leaves are compound and have several, coarsely-toothed, lanceolate leaflets. The veins of these leaflets terminate at the notches in between the teeth.
Water hemlock grows best in wet meadows, thickets and freshwater swamps.
Water hemlock is closely related to the infamous poison hemlock. Like the poison hemlock, water hemlock has fatally toxic roots that, when eaten in small quantity, can cause death. Mistaken for other similar, yet innocuous, members of the apiaceae (carrot) family, water hemlock easily kills livestock, including cows, sheep and horses, that graze in it’s habitat.