Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Fls regular; sep green or yellowish, 3, 4, or more commonly 5, rarely more; pet mostly 5, sometimes fewer or more, each with a nectariferous pit or scale on the upper side at the base; stamens mostly numerous, rarely as few as 5; pistils numerous in a globose, ovoid, or cylindric head; ovule ordinarily 1, erect or ascending; fr an achene; annual or perennial herbs with alternate, entire to much dissected lvs and yellow, white, or rarely red fls; juice acrid, poisonous. (Batrachium, Ceratocephalus, Ficaria) 250+, ± cosmop.
buttercup, crowfoot, spearwort