Ruellia prostrata, like R. patula, is widespread across tropical and subtropical Africa. The former has pubescent ovaries while the latter has glabrous ovaries (there are other differences – ask me). I don’t have anything profound to say about this species at the moment. I’m terribly sorry.
Wild collected, Ethiopia, Tripp & Ensermu #894 (RSA-POM); Photo by Erin Tripp