Mexican petunia, Ruellia caerulea

This Mexican was by a Florida waterway. The flower was about two inches across. It became the first Mexican petunia image, but it's not very typical. These flowers are more often blue and a little smaller. This variety may very well have been developed by horticulture, then added back to the wild. That sort of variation among escaped cultivated plants is not unusual. Native to Mexico, this plant now grows in warm areas from Florida to Queensland, and probably beyond. With us it's in AL, FL, GA, HI, LA, MS, SC, and TX. Polk Co FL, 10/20/15. Acanthus family, Acanthaceae.