Apocynaceae (Dogbane Family); Subfamily Plumerioideae, Tabernaemontaneae Tribe
Forms and Subspecies
The synonyms are occasionally defined as distinct species. These may, however, merely represent varieties, forms, races, et cetera. The natives of Gabon make a distinction between two varieties on the basis of the shapes of the fruit (Brenneisen 1994, 890). The ethnographic literature sometimes distinguishes two varieties (Fernandez 1982):
Tabernanthe iboga var. iboga (iboga vrai, mabasoka)
Tabernanthe iboga var. manii (ñoké)
Iboga vateriana J. Br. et K. Schum.
Tabernanthe albiflora Stapf
Tabernanthe bocca Stapf
Tabernanthe mannii Stapf
Tabernanthe pubescens Pichon
Tabernanthe subsessilis Stapf
Tabernanthe tenuiflora Stapf
Tabernanthes eboka (incorrect spelling in the literature, e.g., Fernandez 1966, 46)
Abona, abonete, aboua, ahua (Pahuin), bocca, boccawurzel, boga, botola, bugensongo (Ngala), dibuga, dibugi, difuma (Eshira), eboga (Fang), eboga bush, ebôga, ébogé, eboghe, eboka (“miracle wood”), elahu (Mongo), eroga, gbana (Gbaya), gifuma, iboa, ibo’a, iboga (Galwa-Mpongwe/ Miene), ibogakraut, ibogain-pflanze, iboga shrub, ibogastrauch, iboga typique (Congo), iboga vrai, ibogawortel (Dutch), ibogawurzel, ikuke (Mongo), inado a ebengabanga (Tshiluba), inaolo a ikakusa (Turumbu), inkomi (Mono), isangola, leboka, liboko (Vili/Yoombe), libuga, libuka, lofondja, lopundja, mabasoka, mbasaoka, mbasoka (Mitsogo), mbondo (Aka Pygmy), meboa (Bakwele), minkolongo (Fang), moabi, mungondo (Eshira), ñoké, nyokä (Mitsogo), obona, obuété, pandu (Mongo), sese (Fang), wunderholz
According to legend, the iboga bush arose from a person, just like many other psychoactive plants. According to the mythology of the West African Fang:
Zame ye Mebege [the last of the creator gods] gave us Eboka. One day . . . he saw . . . the Pygmy Bitamu, high in an Atanga tree, gathering its fruit. He made him fall. He died, and Zame brought his spirit to him. Zame cut off the little fingers and the little toes of the cadaver of the Pygmy and planted them in various parts of the forest. They grew into the Eboka bush. (Schultes and Hofmann 1992, 112)
For many West African tribes, the plant became a “bridge to the ancestors,” an instrument of initiation to the true world, a fetish in which the personal god dwells. The wisdom of the original ancestor, the Pygmy plant expert Bitamu, is embodied in the plant, and his sacrifice established the plant cult. The ingestion of iboga causes one to travel through time. Iboga is a sacrament and a symbol of the power of the forest (the Fang say that “Bwiti is a religion of the trees”).
In West Africa, iboga has been used in fetish cults and in magic since ancient times (Bisset 1989, 21; Pope 1969). In the Congo, its psycho-active effects have been used to enable mediums to be possessed by fetishes (Schleiffer 1979, 49*). Hunters chewed the root so that they could stay awake and retain their strength during long hunting expeditions. It is said that the iboga root gives one the power to remain immobile for two full days while hunting the coveted lion trophies (Bouquet 1969).
Botanical illustration of the West African iboga shrub (Tabernanthe iboga). (From Landrin, Bull. Sc. Pharmacol. 11, 1905)
Iboga found its greatest significance in the reformative cults that developed around the beginning of the twentieth century from the ancestor cults (bieri) of the Neo-Bantu peoples (Fang) and became known as Bwiti (Fernandez 1964; 1966, 44). Administrators in Gabon tried several times to suppress the Bwiti cult, sometimes using such spurious arguments as “Bwiti is a cult of cannibals and ritual murderers” (Schleiffer 1979, 54*). But Bwiti has remained vital in northern Gabon even into the present day and is, in fact, steadily gaining in popularity. The first white person ever to be initiated into the Bwiti cult and to undergo and survive the effects of the iboga root was the Italian ethnobotanist Giorgio Samorini (1993, 1996b).
The first report about the plant and its stimulant and aphrodisiac effects appeared in 1864 (Schultes 1970, 35*). The bush was botanically described in 1889 by Henri E. Baillon (1827– 1895). The primary constituent of the plant, ibogaine, was isolated in 1901; pharmacological investigations of this substance have been conducted primarily in France.
This tropical plant is found in Gabon and the surrounding areas of the Congo and from Cameroon to Angola. It also is planted in many parts of West Africa. It is a typical shade-loving underwood plant that thrives at altitudes from sea level to 1,500 meters. The plant is often encountered along rivers and in marshy areas (Vonk and Leeuwenberg 1989, 11).
Propagation usually occurs with root segments taken from the rootstock or from scions. Propagation from seed is very difficult, as the seeds remain viable only if they have not completely dried.
Tabernanthe iboga can be crossed with Tabernanthe elliptica. Even natural hybrids occur (Vonk and Leeuwenberg 1989, 12 f.). The so-called Kisantu hybrid was described under the name Daturicarpa elliptica x Tabernanthe iboga, but it may have been better interpreted as Tabernanthe elliptica x Tabernaemontana (Pterotabera) inconspicua (Bisset 1989, 24; Massiot et al. 1988).
The evergreen, branching shrub can attain a height of 1.5 to, more rarely, 2 meters. The opposite, lanceolate leaves can grow 10 to 15 cm in length. The shrub develops strong, heavily branching roots that have a brownish rind and yellowish wood. The tiny yellow flowers have a corona 5 to 10 mm in length and often appear in clusters. The pendulous, orange-yellow fruits are ovoid and pointed at the end (18 to 24 mm long). The plant produces a white latex with a powerful scent. In the tropics, the shrub flowers from March to June/July (and sometimes even longer). The fruits ripen at the beginning of the dry period. Both flowers and fruits can appear simultaneously.
The iboga shrub can be easily confused with other members of the genus Tabernanthe. Following the last taxonomic revision of the genus, however, this confusion should be limited to the very similarTabernanthe elliptica (Stapf) Leeuwenberg [syn. Daturicarpa elliptica Stapf, Daturicarpa firmula Stapf, Daturicarpa lanceolata Stapf]. Tabernanthe elliptica distinguishes itself by its copious white latex. The iboga shrub can also be confused with several Tabernaemontana species (Tabernaemontana spp.), regarded as its closest relatives (Vonk and Leeuwenberg 1989, 3).
—Root (tabernanthe radix, tabernanthewurzel, boccawurzel, ibogawurzel, iboga root)
—Root cortex (tabernanthe radicis cortex, tabernanthewurzelrinde, tabernanthe root cortex)
—Leaves (tabernanthe folium, tabernantheblatt, tabernanthe leaves)
The West African iboga shrub (Tabernanthe iboga)
The tiny flowers of the iboga shrub (Tabernanthe iboga)
Preparation and Dosage
In Gabon, the roots are harvested from living plants. A small hole is dug in the ground near the rootstock. Part of the root is removed, but enough of the rootstock is left in the ground that the plant can remain alive and develop new roots.
The root or root cortex is dried and rasped or ground. The extremely bitter, repulsive-tasting root is either eaten and washed down with water or, less frequently, made into a tea.
In the Congo, an aphrodisiac wine is made by steeping the fresh or dried root in palm wine for a few hours and then removing it (Bouquet 1969, 67).
A heaping teaspoon of the root powder acts as a stimulant and produces an agreeable state of euphoria (Samorini 1993, 6). Six to 10 g of the dried root powder induces visions and psychedelic hallucinations. For initiation into the Bwiti cult, one eats 50 to 100 g, and sometimes probably even more (200 g).
A dosage corresponding to 2 to 10 mg per kilogram of body weight (calculated as ibogaine) produces a non-amphetamine-like stimulation of the central nervous system. With an amount corresponding to 40 mg of ibogaine per kilogram, the serotonin receptors are occupied, resulting in LSD-like effects (Brenneisen 1994, 892).
The bark and bark juice were used together with Parquetina and/or Strophanthus species to make arrow poisons (Bisset 1989, 21).
The fruits are edible and do not produce any psychoactive effects (Fernandez 1982, 474). Although leaf extracts contain different alkaloids, they are said to be more pharmacologically active (Bisset 1989, 25).
Iboga roots were or are sometimes prepared together with other plants, only a few of which have been botanically identified (see the table below) (Emboden 1979, 73; Schultes 1970, 36*).
During Bwiti initiation, eyedrops (ibama, ebama) are sometimes dripped into the initiates’ eyes so that they may receive more profound or clearer visions. It is possible that some of the eyedrop preparations may be psychoactive or have synergistic effects with iboga (Samorini 1996c). We have no precise recipes, but some of the ingredients are known:
Costus lucanusianus J. Braun et K. Schum. (Zingiberaceae), Amorphophallus maculatus N.E. Br. (Araceae), Afromomum sanguineum K. Schum. (Zingiberaceae), Euphorbia hermentiana Lem (Euphorbiaceae), Mimosa pigra L. (Leguminosae; cf. Mimosa spp.), Buchholzia macrophylla Pax (Capparidaceae), Elaeophorbia drupifera Stapf (Euphorbiaceae), and the juice of a large millipede (Fernandez 1972, 242 f.; Samorini 1996c).
“The souls fish the pool of eboka to make us fertile. There is a mirror in the pool that reflects heaven and earth, and that is the one that god sees. The wind of creation will enable trees to spring from the ground, but not people, for their spiritual sources are in the water of creation—in the pool of eboka. For this reason, death has an inconsistency for us. The religion of eboka is like the rattan palm, although thorny, it offers a sweet repast to the wanderer. God, the source of all wisdom, has hidden himself and is as hidden as the heart of a palm, but we of the Bwiti cult learn directly from him.”
BWITI SERMON BY EKANG ENGONO IN “UNBELIEVABLY SUBTLE WORDS” (FERNANDEZ 1966, 64)
“Soon the day will begin
the chief has left us
in the beginning, a rope came from the heavens
from our father Nzambe
Humans increased their numbers
And the earth received fertilizing rain
No one can pass the place
where the harp player sits
Except for the primordial ancestors,
who know all things
The heart of the new initiate
is full of bitterness
That of the old is full of wisdom
The young initiate is divided
By the light of the sun and of the moon.”
TEXT OF THE BWITI RITUAL OF THE METSOGO
According to information provided by the Fang, the iboga plant was originally discovered in the rain forest by the Pygmies. The Apinji and Metsogo, who established the foundation of the initiatory use, learned the secret of the consciousness-expanding root from these small rain-forest people. Sometime around 1890, the Fang adopted the ancestor ritual (bieri) from them and fused it with Christian concepts and customs to produce the syncretic Bwiti cult (Samorini 1993). In the process, the iboga plant was occasionally identified with the cult god Bwiti himself (Fernandez 1966, 62 f.). In any case, iboga is regarded as the true tree of knowledge that came directly from the Garden of Eden so that people could use it to recognize God and the world and, initiated into paradisiacal secrets, to spend their life on the earth in joy (Samorini 1993). The Bwiti cult has certain parallels to the North American peyote cult (see Lophophora williamsii) and the Brazilian Santo Daime cult (see ayahuasca), both of which have members ingest a psychoactive substance as a sacrament in a syncretic ritual. The Bwiti cult is first and foremost a rite of initiation:
The story of Bwiti is 150 years long; it arised from the influence of Christendom over the traditional cults in which iboga was used, widespread among different tribes of Gabon and of the neighboring countries. The Bwiti is differentiated in numerous sects, each one constituted by different communities, and the differences among them are particularly due to the degree of absorption of the christian symbols and practices. In all the sects iboga is used as the “true sacrament,” in opposition to the ineffective christian host. . . . [T]he ngozé, or bwitist masses, are performed during three consecutive nights (from Thursday night to Saturday night), during which the faithful eat a “modest” quantity of powdered root of iboga, giving up to dances and songs until the coming of daybreak. . . . [T]he tobe si [is] the initiation rite, celebrated each time a person decides to enter into the religious community. In this case, the novice has to eat a huge quantity of iboga, comparable to hundreds of dosis as those used during the ngozé: a quantity that progressively carry him to a deep and long state of coma, during which his soul makes a trip into the “other world,” while his body lies on the ground, watched by the officiants. Still today, sometimes someone does not awake from the state of unconsciousness, and dies” (Samorini 1995, 105)
The various cult communities, each of which is composed of around fifty people, usually have a temple300 (abeiñ) that is used for initiations as well as special holidays (Easter, Christmas) and the weekly nocturnal masses. Before giving his sermon, the priest of the Bwiti cult will lie, under the influence of iboga, in a grave dug into the ground. He remains there until he has found the words for his sermon (nkobo akyunge, literally “amazing words”). He usually will lie for hours in the grave, coming out after midnight to proclaim his “amazing words” (Fernandez 1966, 46).
A ritual use of iboga root (often in combination with 50 μg of LSD) in ritual circles known as “vision circles” has developed in Europe and the United States as well. The ritual structure borrows from that of Indian mushroom circles (cf. Psilocybe mexicana) and peyote meetings (cf. Lophophora williamsii). Sometimes the vision circle will follow a psychedelic medicine wheel. Here, the participants who sit in the south will ingest Trichocereus pachanoi, those in the east Psilocybe spp., those in the west ayahuasca, and the participants in the north iboga root (Westerhout 1996).
In West Africa, the tradition of making and venerating fetishes for ancestor cults is very ancient and one of the characteristic features of the culture (Koloss 1980). The Fang were already carving anthropomorphic ancestor figures by the end of the nineteenth century. These were used as fetishes in the bieri cult and would later find use in the Bwiti cult as well.
A variety of paraphernalia is used in the iboga cult. The harp is especially important; it is made with great care and is played during the ritual (Swiderski 1970). The music and the texts that are sung with the harp represent the most important cultural artifacts of the Bwiti cult (Grebert 1928). The singer and harp player of the cult community sings Bwiti songs to accompany the soul of the initiate. For example:
So was the beginning. Spirit of earth, spirit of the sky. The place that we traverse. Father Zame, who is the gatekeeper. I come to a new land that is the cemetary. . . . Lightning and Thunder. Sun and Moon. Heaven and Earth. They are all of them twins. They are life and death. They are all twins. The yawning hole of the grave and the new life, they are all twins. . . . Joy, full of joy the ancestors greet you and hear the news. The anxious life of the born is at an end, at an end, at an end. And now come the disciples of death. I go to the dead. . . . Everything is pure, pure. Everything new, new. Everything is light, light. I have seen the dead and I am not afraid! (from Fernandez 1982)
Discography: Bwiti Music
Gabon: Les musicians de la forêt, vol. 1. Ocora 558569. Paris, 1981.
Gabon: Musica da un Microcosmo Equatoriale—Musica Fang Bwiti con esempi musicali Mbiri. Albatros VPA 8232/B. Milan, 1975.
Gabon: Musiques de Mitsogho et des Batéké. Ocora OCR 84. Paris, 1984.
Music from an Equatorial Microcosm: Fang Bwiti Music with Mbiri Selections. Folkway Records FE 4214. New York, 1973. (Recorded by James Fernandez)
Iboga root is used in West African folk medicine as a stimulant, tonic, and aphrodisiac; in cases of nervous weakness; and to treat fever and high blood pressure. Because of its anesthetic properties, it also is used for toothaches (Brennesien 1994, 892). The Metsogo also use iboga roots to divine and diagnose the causes of illness (Prins 1987). In the Congo, iboga is used to treat the tropical sleeping sickness (Hirschfeld and Linsert 1930, 202*).
The Fang use these fetishes, carved from wood, in the West African iboga cult.
The French in equatorial Africa once praised an iboga extract called lambarence as a cure-all and recommended it especially in the treatment of neurasthenia and syphilis (Miller 1985, 50*).
In homeopathic medicine, a mother tincture and various dilutions (Tabernanthe iboga hom.) obtained from the fresh root are used in accordance with the medical description.
The dried root cortex can contain a total of up to 6% monoterpene indole alkaloids (Brennesien 1994, 892; Schultes 1970, 36*). The alkaloid concentration in the entire root is about 1% (Roth et al. 1994, 688*). The alkaloids can be divided into three types: the ibogaine type (ibogaine, tabernanthine, ibogamine, gabonine, ibogaline, et cetera), the voacangine type (voacangine, catharanthine, voacryptine, et cetera), and the voaphylline type (voaphylline) (Brennesien 1994, 890). The main active constituent is ibogaine. Voacangine can be regarded as another important component (cf. Voacanga spp.). The alkaloid mixture varies depending upon the race, location, et cetera. Many of the iboga alkaloids also occur in Tabernae-montana spp.
The seeds contain the alkaloids (–)-catharanthine, (+)-voaphylline, and (–)-coronaridine (Roth et al. 1994, 688*).
The form indigenous to Zaire, which was previously described under the name Tabernanthe pubescens, has been found to contain the following alkaloids: coronaridine, voaphylline, tetrahydroalstonine, voaphylline hydroxyindolenine, 11-hydroxytabersonine, ibogamine, ibogaine, ibogaline, iboxygaine, voacangine, voacangine hydroxyindoleine, voacristine, 3,6-oxido-iboxygaine, 10-hydroxycoronaridine, 10-hydroxyheyneanine, and 3,6-oxidoibogaine (Mulamba et al. 1981).
The Fang describe the visions that follow the ingestion of iboga as “wending through the forest.” They experience carrying the entire wondrous world of the forest within themselves. Reports of visionary encounters with the ancestors are typical (Fernandez 1982, 476 ff.).
Although only a few white people have had the opportunity to use iboga root, their reports are also constant in some respects. They describe powerful yet peaceful visions and especially contact with deceased family members, unknown people, and animals (“ancestors” in the broadest sense). The following represents a typical report of an iboga experience:
A white light rose up from within me. First as an infinitely small point. The point grew in spite of all mathematical definitions. It became larger, but did not form a circle. . . . It became a triangle, or more precisely, a three-cornered crystal that glowed white. I knew that it was the center of the eternal circle. Its three crystalline faces were the past, the present, and the future. All three aspects of time were one, they touched one another and together they created the world. I had the cosmic jewel before me. Indeed, the etymology of cosmos is jewel. The Buddha also holds a magical jewel, from whose brilliance the world arises, in his enlightened hand. Many ochre brown layers lay around the three-cornered crystal. Each one housed another one. All of the layers penetrated into every direction. Every layer was a stage in the development of the universe, in the evolution of life, in the unfolding of consciousness. Every sequence of layers, whether it was that of the past, the present, or the future, transcended into the infinite. There the layers met once more. The infinite was the extreme outer limit of the crystal, and it lay precisely in its center. I saw a culture that is beyond all cultures and yet is inherent to all cultures. I saw gods that are beyond all known gods and yet are contained in all gods. I saw rows of ancestors, all of which are beyond humans and yet have effects upon them even into the present time. I saw the archetypes. They danced in rings around one another in all units of consciousness and led them securely through the universe. Maya is not the appearance of things. Maya is the masks of the archetypes. We need Maya, otherwise we would no longer understand the world. There was no stop to this swirl of insight, one face followed the next. And yet all of the faces remained in existence. I had never remembered faces so well before. Since then, they have never disappeared. I can remember everything clearly, nothing has gotten confused.
The extract of the root has a potent stimulating effect upon the brain that is not comparable to the stimulation produced by amphetamines (cf. ephedrine) (Bert et al. 1988). The effects of the root are also different from those of isolated or pure ibogaine, because the other alkaloids exhibit an affinity to certain receptors or represent antagonists (e.g., tabernanthine has an antagonistic activity toward benzodiazepine and GABA receptors).
Commercial Forms and Regulations
The plant is (still) legal, although there have been attempts to schedule the constituent ibogaine under current drug laws. The mother tincture of the root can be obtained in France and Switzerland. Dilutions (D3 and higher) can be purchased in the United States. Plant material is only rarely available outside of West Africa. Iboga roots are sometimes offered by ethnobotanical specialty sources, but the material is often counterfeit.
“For this reason God left the iboga, so that men would see their bodies as God had made them, as He himself has hidden inside them. Therefore brothers take the iboga, the iboga plant that God gave to Adam and Eve, Obola and Biome.”
A BWITI INITIATE IN “ADAM, EVE, AND IBOGA” (SAMORINI 1993, 4)
See also the entries for Tabernaemontana spp., Alchornea spp., Voacanga spp., ibogaine, and indole alkaloids.
Bert, Maryse, René Marcy, Marie-Anne Quermonne, Michel Cotelle, and Michel Koch. 1988. Nonamphetaminenic central stimulation by alkaloids from ibogaine and vobasine series. Planta Medica 36:191–92.
Binet, J. 1974. Drugs and mysticism: The Bwiti cult of the Fang. Diogenes 86:31–54.
Bisset, N. G. 1989. Tabernanthe: Uses, phytochemistry, and pharmacology anatomy of T. iboga. Wageningen Agricultural University Papers 89 (4): 19–26.
Bouquet, Armand. 1969. Féticheurs et médicines traditionelles du Congo (Brazzaville). Mémoires, no. 36. Paris: ORSTOM.
Brenneisen, Rudolf. 1994. Tabernanthe. In Hagers Handbuch der pharmazeutischen Praxis, 5th ed., 6:890–93. Berlin: Springer.
Caignault, J. C., and J. Delourme-Houdé. 1977. Les alcaloïdes de l’iboga (Tabernanthe iboga H. Bn.). Fitoterapia 48:243–65.
Fernandez, James W. 1964. African religious movements: Types and dynamics. Journal of Modern African Studies 2 (4): 531–49.
———. 1966. Unbelievably subtle words: Representation and integration in the sermons of an African reformative cult. Journal of the History of Religions 6:53–69.
———. 1972. Tabernanthe iboga: Narcotic ecstasis and the work of the ancestors. In Flesh of the gods, ed. Peter T. Furst, 237–59. New York: Praeger.
———. 1982. Bwiti: An ethnography of the religious imagination in Africa. Princeton, N.J.: Princeton University Press.
Fromaget, M. 1986. Contribution du Bwiti mitsogho à l’anthropologie de l’imaginaire: A propos d’un cas de diagnostic divinatoire au Gabon. Anthropos 81:87–107.
Grebert, M. F. 1928. L’art musical chez les Fang du Gabon. Archives Suisses d’Anthropologie Générale 5:75–86.
Koloss, Hans Joachim. 1980. Götter und Ahnen, Hexen und Medizin. In Zum Weltbild in Oku, ed. Walter Raunig, 1–12. Frankfurt/M.: Pinguin-Verlag.
Massiot, Georges, Bernard Richard, Louisette Le Men-Olivier, Jean de Grave, and Clément Delaude. 1988. Alkaloids from leaves of Pterotaberna inconspicua and the Kisantu hybrid problem. Phytochemistry 27 (4): 1085–88.
Mulamba, T., C. Delaude, L. Le Men-Olivier, and J. Lévy. 1981. Alcaloïdes de Tabernanthe pubescens. Journal of Natural Products 44 (2): 184–89.
Naeher, Karl. 1996. Die Droge gegen Drogen. Esotera 8:57–59.
Pope, Harrison G., Jr. 1969. Tabernanthe iboga: An African narcotic plant of social importance. Economic Botany 23:174–84. (Very good bibliography.)
Prins, Marina. 1987. Tabernanthe iboga, die vielseitige Droge Äquatorial-Westafrikas: Divination, Initiation und Besessenheit bei den Mitsogho in Gabun. In Ethnopsychotherapie, ed. A. Dittrich and Ch. Scharfetter, 53–69. Stuttgart: Enke.
Samorini, Giorgio. 1993. Adam, Eve and iboga. Integration 4:4–10.
———. 1995. The Buiti religion and the psychoactive plant Tabernanthe iboga (equatorial Africa). Integration 5:105–14.
———. 1996a. Adam, Eva e iboga: Mi experiencia con los Bwitis del Gabón. Takiwasi 4 (2): 63–75.
———. 1996b. El rito de iniciación a la religión Buiti (Secta Ndea Narizanga, Gabon). Lecture given at the II° Congrès International per l’Estudio dels Estats Modificats de Consciència, 3–7 October 1994, Llèida.
———. 1996c. Visionary eye-drops. Eleusis 5:27–32.
———. 1997. Una bibliografia commentata sulla religione Buiti. Eleusis 7:3–16.
———. 1998. The initiation rite in the Bwiti religion (Ndea Narizanga sect, Gabon). Yearbook for Ethnomedicine and the Study of Consciousness, 1997/1998 (6–7): 39–55. Berlin: VWB.
Swiderski, Stanislaw. 1964. Symbol- und Kultwandel des Geheimbundes “Bwiti” in Gabun. Anthropos 59 (5/6).
———. 1965. Le Bwiti, société d’initiation chez les Apindji au Gabon. Anthropos 60: 541–76.
———. 1970. La harpe sacrée dans les cultes syncrétiques en Gabon. Anthropos 65:833–57.
———. 1972. Die sakrale Verzierung der Tempel in den synkretistischen Sekten in Gabun. Mitteilungen der Anthropologischen Gesellschaft in Wien 102:105–13.
———. 1981. Les visions d’iboga. Anthropos 76:393–429.
———. 1982. Le rite mortuaire pour un initié au Bouiti. Anthropos 77:741–54.
———. 1990. La religion Bouiti. 5 vols. New York, Ottawa, and Toronto: Legas.
Vonk, G. J. A., and A. J. M. Leeuwenberg. 1989. A taxonomic revision of the genus Tabernanthe and a study of wood anatomy of T. iboga. Wageningen Agricultural University Papers 89 (4): 1–18.
Westerhout, Hans. 1996. Een Vision Circle met ibogaine. Pan 3:9–12.