This pesky weed comes in several different varieties. Most are biennials (meaning the weed cycle will last for two years). The root is a fleshly taproot the first year and a fibrous root system forms the second year, continuing the weed cycle. With some varieties, thistle can shoot up eight feet off of a main shoot. This can lead to new thistle plants appearing within weeks after a treatment has been applied if the main plant has not been controlled. The tip of the blade is pointed and the margins are toothed with spines, making it an extremely annoying weed in areas where there is activity taking place.