The persistence of prairie as Ruellia humilis

I spotted this plant along the roadside of US 52 a couple three miles SE of Lafayette.  It was a bit different color than the familiar chicory common on roadsides.  This is Ruellia humilis, a prairie plant.  Once this was prairie land and this Ruellia is the last remnant of the prairie.  I didn't see any other prairie plants anywhere nearby.   All ther rest of the roadside for miles are the common plants of disturbed areas (some call them weeds).  These two photos above taken Aug. 13, 2013 in Tippecanoe County.

Link to previous post on Ruellia humilis in a prairie remnant along US 52 in Benton County:

The photo directly above is Ruellia humilis at Prairie Creek Barrens in Daviess County, July 27, 2013.

Link to Ruellia humilis: