Polygonum tenue
Polygonum tenue, the slender knotweed or pleat-leaf knotweed, is a North American species of plants in the buckwheat family. it is widespread across south-central Canada and the eastern and central United States from Maine to Georgia, west as far as Minnesota, South Dakota, Nebraska, and Texas.
Polygonum tenue is a herb up to tall. Stems are green or brown, not wiry. Leaves are narrow, up to long. Flowers are pink or white.