This beautiful flower takes advantage of the early days of spring, when the trees in the open woods are still mostly leafless, to get most of its growing and blooming done. By summer it’s gone. It looks a bit like a white (or sometimes pink) buttercup, and indeed it belongs to the same family. This plant was blooming in late April in the Squaw Run valley in Fox Chapel.
Gray places this species in the genus Anemonella:
Involucre compound, at the base of an umbel of flowers. Sepals 5-10, whiteand conspicuous. Petals none. Achenes 4-15, ovoid, terete, strongly 8-10-ribbed, sessile. Stigma terminal, broad and depressed. Low glabrous perennial; leaves all radical, compound. (Name a diminutive of Anemone, to which this plant has sometimes been referred.)
A. thalictroides (L.) Spach. (RUE ANEMONE.) Stem and slender petiole of radical leaf (1-3 dm. high) rising from a cluster of thickened tuberous roots; leaves 2-3-ternately compound; leaflets roundish, somewhat 3-lobed at the end, cordate at the base, long-petiolulate, those of the 2-3-leaved 1-2-ternate involucre similar; flowers several in an umbel; sepals oval (1.2 cm. long, sometimes pinkish), not early deciduous. (Syndesmon Hoffmannsegg.; Thalictrum anemonoides Michx.) Woods, common, s. N. H. to Minn., Kan., Tenn., and n. w. Fla. Rarely the sepals, stamens or involucre are variously modified.