Expect a major blow to the head from this super-potent strain. A pure sativa, Durban Poison is the beloved inbred descendant of a sativa strain grown in South Africa. Ed Rosenthal, an American cannabis activist, discovered the original strain and brought in back to the United States in the 1970s. It has long been a favorite of stoners and medical marijuana patients here. Durban Poison has THC levels that can reach 24%, making it one of the world’s more powerful strains.