This southeastern annual occurs mostly on sandy soils of the Coastal Plain, but with significant disjunctions in Tenn. as well as Ky. There has been some confusion with P. curstissii in Ky., but the records mapped here from DAVI and TODD are based on correctly identified colls. (KY). P. mariana differs from curtisii and nuttallii in its promptly deciduous bracts (versus persistent), a character shared with the larger flowered sanguinea. Its lateral sepals are intermediate in length (2.7-3.6 mm), and its racemes are intermediate in width (6-11 mm).