Devil's Club Root Bark, or Opiopanax horridum, grows in the moist forests of the Pacific Northwestern United States and Canada. Another common name for these herbs is the Devil's Walking Stick. It is a large deciduous shrub that grows approximately six feet tall and wide, although in ideal conditions in rainforests it has been known to reach larger proportions of more than fifteen feet. These frost tender herbs go into flower during the summer months. The "devil" reference in this herbs' name refers to the spiny thorns that cover the stems of the plant. The term "club" refers to the flowerhead of the plant, which consists of umbels featuring small, five-petaled flowers. The name Opiopanax horridum is the Latin name for the plant, the first word being the genus and the second the species. Horridum also refers to the fact that the plant has prickly spines, and thus the Devil connotation.