Essiac or Essiac Tea is a blen of herbs used to make a tea that is believed by some and questioned by others to have cancer-treating properties. It was discovered by a Canadian nurse, Rene Caisse, who named it after her last name spelled backwards. The original formula is believed to have its roots in native Canadian Ojibwa medicine and contains greater burdock root (Arctium lappa), slippery elm inner bark (Ulmus rubra, formerly known as Ulmus fulva), sheep sorrel (Rumex acetosella), and Indian or Turkish rhubarb root (Rheum officinale).