Hibiscus trionum by Wikiwide

Flower-of-an-Hour originally grew to east of Mediterranean, but it spread throughout southern Europe both as a weed and as a garden plant.
Common names
Flower-of-the-Hour
Modesty
Shoofly
Venice mallow

Credits for original to Rob, who kindly allowed ("Non-commercial use of the one image would be OK") to use the image (http://www.robsplants.com/images/portrait/HibiscusTrionum090718.jpg) from the webpage (http://www.robsplants.com/plants/HibisTrion.php) of his website (www.robsplants.com).