Potentilla norvegica L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Stout, leafy annual to short-lived perennial, the stem mostly branched and many-fld, hirsute below, subtomentose above; lfls 3, elliptic to broadly obovate, to 8 cm, crenate; fls yellow, nearly 1 cm wide, the pet nearly as long as the sep; bractlets and sep lance- ovate, subequal at anthesis, the sep accrescent in fr and to 15 mm; stamens usually 20; anthers 0.3 mm; achenes flattened, 1 mm, usually marked with curved longitudinal ridges; 2n=42, 56, 70. In a wide variety of habitats; circumboreal, s. in Amer. to S.C., Tenn., Tex., and Calif. June–Aug. The native American plants tend to differ slightly from the European ones, and have been segregated as P. monspeliensis L. or P. norvegica var. hirsuta (Michx.) Torr. & A. Gray, but no clear distinction can be made, and the Eurasian phase has also apparently been intr. into our range.