Plant: Plant 6-12 dm, Perennial, glabrous, stout; roots clustered, fibrous or ± tuberous; stem erect or ascending, branched Leaves: petiole 1-8 dm, segmented; blade 6-25 cm, 7-18 cm wide, oblong to ovate, 1-pinnate; leaflets 1-4 cm, linear or lanceolate, serrate or irregularly cut INFLORESCENCE: compound umbels; peduncle 4-10 cm; bracts 6-10, 3-15 mm, linear or lanceolate, acute, entire or irregularly cut, reflexed; bractlets 4-8, 1-3 mm, linear-lanceolate; rays 10-20, 1.5-3 cm, slender, subequal; pedicels 3-5 mm Flowers: small, many, sometimes ± bilateral; calyx lobes 0 or minute; petals wide, free, white, narrowed at tips, outer slightly > others; stamens 5; pistil 1, ovary inferior, 2-chambered, generally with a ± conic, persistent projection or platform on top subtending 2 free styles Fruit: 2 dry, 1-seeded halves that separate from each other but generally remain attached for some time to a central axis, ovate to round, 2-3 mm wide, slightly compressed side-to-side; ribs prominent, subequal, corky; oil tubes per rib-interval 1-3; fruit axis entire or divided to base, adhering to fruit halves or not; Seed: face flat Misc: Wet soil of swamps, marshes, streambanks; < 2000 m.; Jul-Aug