Much like Hydrocotyle; fr orbicular to reniform, flattened laterally, constricted at the commissure, with conspicuous primary dorsal ribs and 2 well developed secondary ones; umbels 1 or few, arising from the base, simple, head-like, with few (2-5) subsessile to short-pedicellate white fls; bracts 2, ovate; sep obsolete; perennial herbs with simple lvs. 40, mainly S. Hemisphere.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.