Looks like some sort of thistle...maybe this one: Purple Thistle (Cirsium horridulum)
Family: Aster (Asteraceae)
Hardiness: North, Central and South Florida
Growth Habit: Basal leaves 12-18 inches wide that form a round rosette. Flowers grow on 1- to 3-foot flower spikes in springtime. All parts of the plant, including seeds, have sharp spines.
Soil: Thistles are very drought tolerant.
Exposure: Full sun or light shade
Garden tips: Preserve natural stands of thistles that occur in areas not regularly mowed. They coexist well with lovegrass, and their flowers are long-lived. After flowering, the plants retain interest by forming cottony white seed heads that shatter to the wind. Purple thistle is the host plant for the little metalmark caterpillar and is visited by many butterflies, including swallowtails.