The siidal areas of the West Arnazonia in Peru are home to the Huachipaire and Zapiteri, which are associated with the Mashco Group and connected to the Arawak language family. Among the Huachipaire, the presence of a shrub with haliucinatory properties has been discovered. The same is called xayapa (Brugmancia insignis). The authors examine the plants, psycho-medical and rnythic questions associated with the said shrub. Since it is a narrow-limited cultural area - the Huachipaire and Zapiteri live in the Andean outlet area - it is proposed to consider xayapa and its use as newer innovation. The indians who have submitted to the intoxication are unable to relate their hallucinations or to draw a sketch of them. Of the several Mashco groups, only two of surviving ones know the practice of the intoxication with xayapa. These are the related groups of the Huachipaire and the Zapiteri living in the isolated andean riverheads and foothills. To the west, they limit with the Machiguenga, and the contacts resulted in marriages in some instances. The Amaracaire, located in the center of the mashco area and always suffering attacks from the Zapiteri, ignore the use of both xayapa and tobacco. In contrast with the archaic Amaracaire, the active Huachipaire and Zapiteri have learned the use of the xayapa from their western neighbours not long ago. Moreover, we know that the Machiguenga employ a hallucinogenous Solanaceae. The incorporation of the xaydpa to the Huachipaire and Zapiteri culture has been rendered possible by the dualistic conception of body and soul, as we have said, and the exigence of depuration and renowing of the first, which issues as a consequence. Since it is perhaps a recent innovation, the associated mythology is not very rich, and no links exist with the principal theophanies of the mashco culture.