Rough-Fruited Cinquefoil (Sulphur Cinquefoil)
A stout, leafy, very hairy, tall, much-branched perennial, sometimes in large colonies. Flowers with 5 slightly notched petals, longer than the calyx lobes, light yellow to cream, up to 50 stamens, in flat clusters. Blooms May-August. Leaves 5- to 7-divided, with ovate, toothed leaflets; fingerlike. The nodes on the stems have leafy stipules. Basal leaves on long stalks, stem leaves on shorter stalks or stalkless.
Similar species: There are 7 Potentilla species recorded for Missouri. Rough cinquefoil (P. norvegica) apparently also came to us from Europe and is scattered in the northern and western halves of Missouri. Its flowers are bright yellow, arising on stalks from the leaf axils, and the 5 petals and 5 sepals are about equally long. It blooms May-October. The leaves are 3-divided, with the leaflets elliptical to broadly ovate; toothed.