Polygonum spergulariiforme
Polygonum spergulariiforme is a North American species of flowering plants in the buckwheat family known by the common name spurry knotweed or fall knotweed. It grows in western Canada and the western United States.
Polygonum spergulariiforme is a green, branching herb up to tall. Leaves are narrow, up to long. Flowers are pink or white, in dense, elongated clumps. The plant flowers from June to October, later than some of its relatives.