Researchers have developed several indices to estimate the significance of plant species for humans. We build on previous methods in ethnobotany and anthropology to develop a new way to value plant species along three dimensions: cultural, practical, and economic. We used interview and observational data on the use of wild plants by the Tsimane', a foraging-horticultural society in the Bolivian Amazon. We calculated the cultural, practical, economic, and total values of 114 plant species from 46 families. We found a low correlation between the practical and the cultural values of species: some species rarely used were frequently mentioned in interviews, whereas some species frequently used were rarely mentioned in interviews. Indices of cultural, practical, and economic value measure different dimensions of the importance of plant species to society. The combination of the three indices offers a more comprehensive valuation of the significance of plants for humans than the use of only one index.