Xyris panacea  Xyris panacea, also called St. Marks yelloweyed grass, is a rare North American species of flowering plant in the yellow-eyed-grass family. It has been found only in the Florida Panhandle in the southeastern United States. "Xyris panacea " is a perennial herb up to 130 cm (52 inches or 4 1/3 feet) tall with long and narrow leaves up to 50 cm (20 inches) long, and yellow flowers.