Parietaria pensylvanica Muhl. ex Willd.
Habitat: Gravelly beaches, dry woods, and moist banks; sometimes weedy in areas where it is more common.
Range: Maine to British Columbia, south to Florida, Texas, and Nevada.
Phenology: Flowers May to September.
Synonyms: Parietaria obtusa Rydb. ex Small; Parietaria occidentalisRydb.; Parietaria pensylvanica Muhl. ex Willd. var. obtusa (Rydb. ex Small) Shinners.
Known Distribution in Maine: This rare plant has been documented from a total of 1 town(s) in the following county(ies): Hancock. The species is believed to be extirpated from Maine.