Also spotted on a street corner by an abandoned lot in northeast Florida. I thought it might be Chicory (Chicorium intybus), but when I looked at photos of Chicory, the flowers didn't seem quite right. The plant was shallow rooted without much root structure (I know that because I just had to dig a few up to bring home to try to grow in my garden. Beautiful blue flower - couldn't resist the urge to propagate. LOL)
Jeremy
