Polygonella myriophylla

About

Polygonum dentoceras is a rare species of flowering plant in the knotweed family known by the common names sandlace, woody wireweed, and Small's jointweed. It is endemic to Florida in the United States, where it is limited to the central ridges of the peninsula, including the Lake Wales Ridge. It is threatened by the loss and degradation of its habitat. It is a federally listed endangered species of the United States.

Summary from Wikipedia