Polygonum tenue, the slender knotweed or pleat-leaf knotweed, is a North American species of plant in the buckwheat family. It is widespread across south-central Canada (Ontario) and the eastern and central United States from Maine to Georgia, west as far as Minnesota, South Dakota, Nebraska, and Texas (though apparently now extirpated from Maine and New Hampshire).Biota of North America Program 2014 county distribution map
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.Flora of North America, Polygonum tenue Michaux, 1803. Slender or pleat-leaf knotweed
References
External links photo of herbarium specimen at Missouri Botanical Garden, collected in Missouri in 1990