This species (as well as var. maculata) is widespread across temperate regions of North America. In Ky. it is associated with varied types of wetland, and sometimes survives in ditches and low field margins, but it is uncommon to absent in more agricultural landscapes (where perhaps reduced by drainage, trampling and mowing). A closely related segregate known as C. maculata var. bolanderi (S. Watson) Mulligan may also be expected in Ky. (Mulligan 1980; W). That taxon is reported from east-central states to the Great Plains, but it remains poorly understood and poorly documented. It is distinguished by its seeds, with relatively narrow ribs and more abrupt constriction at the junction between pairs (W). Cicuta maculata is lethally toxic to mammals, but caused by chemistry (polyynes) distinct from the toxic alien biennial, Conium maculatum (alkaloids). Toxicity is concentrated in the rhizomes and tuberous roots. Shoots lack extensive purple stripes, in contrast to Conium, but there are purple patches at nodes of leaves and leaflets; these marks could be aposematic (Lev-Yadun 2009).