Fr broadly ovoid to suborbicular, slightly flattened laterally, the dorsal and intermediate ribs narrow and elevated, the lateral ones contiguous, much broader and usually rounded; oil-tubes solitary in the intervals, 2 on the commissure; carpophore wanting; umbels axillary, simple, peduncled; bracts few, minute; pedicels short, at maturity spreading or recurved; sep obsolete; pet white; stylopodium depressed or none; small aquatic perennials with creeping rhizomatous stems emitting from each node one or a few linear-spathulate, transversely septate phyllodes. 20, New World and Australia.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.