This paper offers the first characterization of the ethnobiological taxonomic system used by the Kakataibo people (Pano, Peru) to classify and organize their knowledge about nature. The study follows the six ranks proposed for folk taxonomies (see Berlin et al 197; Berlin 1992), but the data suggest that the Kakataibo taxonomic system exhibits an extra taxonomic level in association with culturally and perceptually more salient categories, producing highly complex classifications (non-salient categories exhibit much simpler internal organizations). This paper also demonstrates the existence of overlapping plant classifications, which seem to be relevant for the understanding of the whole Kakataibo taxonomic system.