Fr ovoid to orbicular, flattened laterally, with thick corky ribs; oil-tubes solitary in the intervals, 2 on the commissure; umbels compound; bracts none or few, narrow, and inconspicuous; bractlets narrow, several, rarely none; sep well developed, triangular; pet white; stylopodium depressed or low-conic; carpophore bifid to the base, deciduous; glabrous, violently poisonous perennials, the tuberous-thickened base of the stem hollow, with well developed transverse partitions; roots clustered, generally some tuberous-thickened; lvs once to thrice pinnate or ternate-pinnate, most spp. with well defined lfls. 4, 1 circumboreal, the others N. Amer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.