Many organisms contain psychoactive chemicals, often evolving as a defence mechanism to protect the plant from predators. For example, members of the tobbacco family of plants, Nicotiana, have evolved to produce nicotine which overpowers the nervous systems of small animals/insects which attempt to eat the plant, thus killing them and preventing the plant from being eaten. This article also lists other organisms that produce psychoactive chemicals, such as fungi.
- Psilocin (4-HO-DMT) & Psilocybin - Psilocybe genus of mushrooms, e.g. Psilocybe cubensis.
- Dimethyltryptamine (DMT) - Many plants and mammals (including humans).
- Bufotenin (5-HO-DMT) - Various species of toads, mushrooms, plants and mammals (including humans).
- Ephedrine - plants of the Ephedra genus.
- Mescaline - several species of cacti including Echinopsis pachanoi (peyote), Echinopsis pachanoi (San Pedro) and Echinopsis peruviana (Peruvian Torch), plus several plant species.
- Atropine - plants in the nightshade family inlcuding Atropa belladonna (deadly nightshade), Datura stramonium (jimsonweed), Mandragora officinarum (mandrake) and several others.
- Cocaine (and Ecgonine) - Erythroxylum coca (coca) plant.
- Caffeine - Plants of the Coffea (coffee) genus and the Camellia sinensis (tea) and Theobroma cacao (cocoa) plant (plus several others).
- Theobromine - Theobroma cacao and Camellia sinensis plants.