In the Amazon rainforest there grow two plants: the mariri (Banisteriopsi caapi) and the chacrona (Psychotria viridis), which have been used by native Indians for hundreds of years to make an infusion. The infusion, known as ‘hoasca tea’, is no ordinary herbal brew but one with psychoactive properties. The leaves of these plants contain dimethyltryptamine (DMT), which has hallucinogenic effects, and beta-carbolines, which are monoamine oxidase inhibitors that prevent the degradation of DMT in the gastrointestinal tract. The preparation and consumption of these substances are legal in Brazil; although the Federal Council for Narcotics (CONFEN) states that they can only be used during recognised rituals.