Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Hypanthium turbinate or hemispheric; sep commonly imbricate; bractlets linear to oblong, or wanting; pet elliptic to obovate; stamens 10–many; ovaries numerous on an elongate, cylindric receptacle; style filiform, elongate; achenes tipped by the long, persistent style; fibrous-rooted perennial herbs with variable foliage, the lower lvs pinnate, the middle smaller and commonly trifoliolate, the upper often simple; fls solitary to many in terminal corymbs; pet white to yellow, or suffused with pink or purple. (Sieversia) 50, mostly N. Hemisphere.