Smooth or hairy, delicate, freely branched perennial, from slender underground stems with segmented white tubers resembling a "rattlesnake's rattle". Leaves opposite, longstalked, lance-shaped, usually with a nearly flat base. Stems square. Flowers white to pink with purple spots. Reproduces primarily by tubers. Found in turf, roadsides, thickets and shrub borders. Native to Florida until it escaped in the 1940s or 1950s. Now found from North Carolina to Texas. Thought to be moved with nursery stock and ornamental plants.