Fr somewhat flattened dorsally, the lateral and usually 1 or more of the dorsal ribs conspicuously winged; umbels compound, often head-like; involucre present and usually conspicuous, only on the outer margin of the umbellets; stylopodium wanting; low, acaulescent or short-stemmed perennials with compound lvs and white, yellow, or purple fls. 45, w. N. Amer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.