Cicuta maculata is a perennial herb to 2 m tall, sap yellowish, pungent (similar to parsnip). Roots clustered, tuberous, roots gradually consumed by growth, flowering and fruiting, but producing an overwintering, perenniating shoot before end of season; rootstock at base of stem, stout, hollow, with diaphrams of pith (Kingsbury 1964), often mottled with purple, upper stem hollow, much branched.
Leaves alternate, 2-3 times pinnately compound, leaflets in groups of 3, spring basal leaves to 1 m long, leaflets to 10 cm, narrow, toothed, small veins end in notches between marginal teeth, upper leaves often simple, main secondary veins ending in a sinus (notch between teeth) from which one fork often extends to the end of a tooth, base of leaf stalk sheathing stem.
Flowers white, small, in umbrella-shaped clusters to 12 cm wide; inflorescence longer than leafy part of stem, pollinated by unspecialized insects; blooms June-July.
Fruit dry, to 0.4 cm, rounded, prominent pale brown ribs separated by darker stripes; fruits July through autumn. Seeds covered by a spongy coat that keeps them afloat for some time, dispersed by water. Seeds only germinate after immersion (Mulligan and Munro 1981).
Wetland status: OBL.
Frequency in NYC: Very infrequent.
Habitat: Open swamps and marshes.
Notes: Very poisonous, the toxin is a complex, unsaturated alcohol called cicutoxin, it acts on the central nervous system causing violent convulsions and can be lethal. Host plant of the rust fungi Puccinia cicutae and Uromyces lineolatus (Basidiomycotina: Hemibasidiomycetes), (Mulligan and Munro 1981). Apiaceae of open sites are eaten by larvae of the black swallowtail butterfly, Papilio polyxenes Papilionidae (Tallamy 2003; Pyle 1981).