Fr elliptic or oblong to suborbicular, strongly flattened dorsally; dorsal ribs filiform; lateral ribs expanded into a thin or thick wing bearing a longitudinal nerve near the pericarp, the fr therefore apparently exhibiting 5 filiform ribs on each side; oil-tubes solitary in the intervals, 2–6 on the commissure; carpophore bifid to the base; umbels few, loose, open, compound; bracts and bractlets few, linear or filiform, or none; sep minute or none; pet white; stylopodium conic; erect glabrous herbs of marshes, from a cluster of fibrous or tuberous-thickened roots, sometimes also rhizomatous; lvs once pinnate or reduced to bladeless phyllodes. 6, N. Amer.
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