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 (British Columbia and Saskatchewan) and the western United States (primarily Washington, Oregon, and northern and central California but with a few isolated populations in Idaho, Wyoming and Montana).Biota of North America Program 2014 county distribution map
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.
References
External links Oregon Flora Image Project, University of Hawai'i, Polygonum spergulariiforme