Anemonoides lancifolia (formerly known as Anemone lancifolia), the lanceleaf anemone or mountain thimbleweed, is an herbaceous plant species in the family Ranunculaceae.

This species much resembles Anemonoides quinquefolia, of which it was formerly considered a subspecies,[1] except that it is larger growing.

After flowering, fruits called achenes are formed in a small cluster; each achene is 3.5–5 mm long, lacks wings and has a straight or partly curved beak that is 1–1.5 mm long.

Both the Latin and common names reference the leaf shape, with narrower leaflets, with a distinctive serration when compared to A. quinquefolia.

Anemone lancifolia is normally found growing in rich damp soils in woods.