persicaria

Any of a group of plants belonging to the dock family, found growing in waste places and arable land, often near water. Common persicaria (P. persicaria) is sprawling in shape and has lance-shaped, black-spotted leaves and spikes of pink flowers. Pale persicaria (P. lapathifolium) is slightly larger, with pale dots on the leaves, and heads of usually white flowers. Both are found throughout much of the northern hemisphere. (Genus Polygonum, family Polygonaceae.)