what is bull thistle
(Cirsium vulgare) Bull thistle (Cirsium vulgare (savi) tenore) is a biennial forb that was introduced to North America as a seed contaminant and is now widespread. Gumdrop-shaped flowers are pinkish to dark purple in color and 1 Â½ to 2 inches in diameter. The flower bracts are somewhat tapered and covered with spines.