Herbs, perennial, stout, glabrous. Rootstock swollen, with transverse air chambers, roots fascicled. Stems tall, erect, hollow, branched above, striate. Leaves petiolate, sheath narrow, clasping, membranous; leaf blade (1–)2–3-pinnate; ultimate segments narrow, linear-lanceolate or lanceolate, serrate or dentate. Umbels compound, lax, terminal or lateral; bracts absent or few, inconspicuous; rays numerous, long, slender, ascending-spreading; bracteoles numerous, narrow, longer or shorter than the flowers. Calyx teeth conspicuous, ovate-triangular. Petals white or greenish-white, obovate or suborbicular, apex narrow, inflexed. Stylopodium depressed; styles slender, reflexed when mature. Fruit ovoid-globose, rounded at both ends or base cordate, flattened laterally, glabrous; ribs 5, thick, corky; vittae 1 in each furrow, 2 on commissure. Seed face plane or slightly concave. Carpophore 2-fid.
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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.
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