Button snakeroot eryngo, button snakeroot, corn snakeroot, eryngo, feverweed, rattlesnake flag, rattlesnake master, rattlesnake weed, water eryngo.
An erect, coarse-branched, perennial that grows to ½ to 5 feet in height. It has firm elongate-to-lanceolate lower leaves; upper leaves are sessile. The plant bears fruit from September to November.
Late July to September.
Fresh to brackish marshes, streams, ponds and bogs, and wet pinelands.
Rootstock in fall.
In large doses, infusions have been used as emetics. Also used as a diaphoretic and expectorant.