Iboga is used in a way that has almost no parallel among sacred plants. Where most traditions take a plant repeatedly and in moderate amounts, Bwiti takes it once, in an overwhelming dose, over an initiation lasting several days, and many initiates never take a comparable amount again.
Bwiti is an initiatory religion of Gabon, strongest among the Fang, the Mitsogo and the Apindji, organised around a temple, a harp, drums and long night ceremonies. The initiate is prepared, then given quantities of scraped root bark over many hours under close supervision, since the dose is genuinely dangerous and deaths have occurred. What follows is understood as a journey: the initiate crosses to the land of the dead, meets the ancestors, and is shown the origins of things. On returning they are a member, and they have seen for themselves rather than been told.
The structure is a rite of passage in the strict sense, with separation, ordeal and return, and the plant is the ordeal. Subsequent participation is about music, dance and communion with the ancestors, and uses far smaller amounts.
Bwiti took on Christian vocabulary and imagery during the colonial period, and different branches sit at different distances from Christianity, but the ancestor cult beneath is continuous and was not replaced.