Pennell indicated that P. digitalis is probably native to the Mississippi River Basin and that it has been introduced elsewhere, especially to the northeast and east, thus it closely parallels the occurence of P. tubaeflorus, another polyploid species of the Great Plains.
This species is the most widespread of the ones east of the Mississippi River.
Photos by Andi Wolfe ©2016 - If you would like to use any of these photos, contact Andi Wolfe at Ohio State University to seek permission.
McGregor RL, Barkley TM. 1986. Flora of the Great Plains. Lawrence Kansas: University Press of Kansas.