This midwestern species has declined across much of its range. It is unknown across southeastern states beyond se. Ohio, w. Ky., c. Tenn. and n. Miss. Within those states, it is a rare remnant of native grasslands on relatively deep, fertile, submesic soils. Yet Short (1840) noted, under the synonym P. illinoensis: "abundant in the barrens of Kentucky, as well as the prairies of Illinois." A coll. of Short from "barrens of Ky." is mounted with a coll. from La. at GH (Holmes & Singhurst 2012). Most records from Ky. are old or obscure, and the species may only be known today from Fort Campbell (TRIG) and perhaps the "Big Clifty" grassland remnant in GRAY (coll. by C. & J. Baskin at APSC).