Parietaria pensylvanica is a species of flowering plant in the nettle family known by the common name Pennsylvania pellitory. It is native to much of North America including every province in Canada except the Maritimes and Newfoundland and Labrador, Yukon Territory, every state in the United States except Alaska and Hawaii, plus northern Mexico. It grows in many types of habitat, including disturbed areas. It is an annual herb growing decumbent or erect to a maximum height near half a meter. The alternately arranged leaves are lance-shaped or oval with a pointed tip and measure up to 9 centimeters in length. The inflorescence is a cluster of flowers emerging from the leaf axils. The flower lacks petals but it has tiny pointed reddish brown sepals.