Chromolaena frustrata

Chromolaena frustrata called Cape Sable false thoroughwort, or Cape Sable thoroughwort, is a rare North American species of flowering shrub in the sunflower family. It is found only in southern Florida, on the Florida Keys, inside Everglades National Park, and other nearby low-lying areas. It grows on coastal rock outcrops, the edges of hammocks, and other undisturbed sites at elevations less than 10 meters (33 feet) above sea level.
"Chromolaena frustrata" is a perennial herb rarely more than 25 cm (10 inches) tall. Flower heads are produced in groups of 2-6. The heads contain blue or lavender disc florets but no ray florets.