Family, Rose. Color, dark purple. Calyx, open, 1 inch broad, 5-cleft, purple inside; bractlets between the divisions. Corolla, of 5 purple petals, shorter than the calyx. Stamens, numerous. Fruit, of several achenes in a roundish head on a large and spongy receptacle. Flowers, few, clustered in a flat cyme from a smooth stem which roots at the base. Leaves, pinnate, with 5 to 7 oblong, toothed leaflets, light green above, downy beneath. June to August.
Cold bogs from Pennsylvania and New Jersey northward.