Fr broadly ovoid or globose-ovoid, evidently short-beaked, subterete or slightly flattened laterally; dorsal ribs narrow, prominent, the lateral ones low but broadly corky-thickened; oil-tubes solitary in the intervals, 2 on the commissure; carpophore merely notched at the top; glabrous annual from fascicled fibrous roots; basal lvs slender, petiolate, entire, cross-septate; cauline lvs petiolate, with 3-5 narrow, entire, flat but cross-septate lfls, invol and involucels wanting or of a few slender members; rays and pedicels rather few, unequal, spreading-ascending; cal-teeth evident, persistent; pet white; stylopodium conic. Monospecific.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.