Polygonum utahense, the Utah knotweed, is an unresolved name for a putative North American species of plants in the buckwheat family. It has been found only in the States of Utah and Arizona in the southwestern United States. Polygonum utahense is a herb up to 50 cm (20 in) tall. Stems are green or brown, not wiry. Leaves are narrow, up to 4 cm (1.6 in) long. Flowers are pink or white.