Anemone riparia (Thimble weed) is an upright growing herbaceous plant species in the genus Anemone and family Ranunculaceae. Plants grow 30–100 centimetres (12–39 in) tall, flowering early summer but often found flowering till mid August, the flowers are greenish-white, white or even sometimes red tinted, 2–3 centimetres (0.79–1.18 in) wide. After flowering the fruits are produced in a dense rounded, to rounded columned heads 8 millimetres (0.31 in) thick. When the fruits, called achenes, are ripe they have gray-white colored, densely woolly styles, that allow them to blow away in the wind. This species is similar to Anemone cylindrica and Anemone virginiana. Native from Eastern North America where it is found growing on rocky banks and in open woods. The species validity in the past has b