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The well-being of the global human population rests on provisioning services delivered by 12% of the Earth's â 1/4400,000 plant species 1. Plant utilization by humans is influenced by species traits 2-4, but it is not well understood which traits underpin different human needs 5. Here, we focus on palms (Arecaceae), one of the most economically important plant groups globally 6, and demonstrate that provisioning services related to basic needs, such as food and medicine, show a strong link to fundamental functional and geographic traits. We integrate data from 2,201 interviews on plant utilization from three biomes in South America - spanning 68 communities, 43 ethnic groups and 2,221 plant uses - with a dataset of 4 traits (leaf length, stem volume, fruit volume, geographic range size) and a species-level phylogeny 7. For all 208 palm species occurring in our study area, we test for relations between their traits and perceived value. We find that people preferentially use large, widespread species rather than small, narrow-ranged species, and that different traits are linked to different uses. Further, plant size and geographic range size are stronger predictors of ecosystem service realization for palm services related to basic human needs than less-basic needs (for example, ritual). These findings suggest that reliance on plant size and availability may have prevented our optimal realization of wild-plant services, since ecologically rare yet functionally important (for example, chemically) clades may have been overlooked. Beyond expanding our understanding of how local people use biodiversity in mega-diverse regions, our trait- and phylogeny-based approach helps to understand the processes that underpin ecosystem service realization, a necessary step to meet societal needs in a changing world with a growing human population., This study was funded by the European Union, 7th Framework Programme (FP7-PALMS-Contract no. 212631, to H.B.), and also supported by the Russell E. Train Education for Nature Program of the WWF, Anne S. Chatham Fellowship of the Garden Club of America, William L. Brown Center, Universidad Autónoma de Madrid travel grants programme, and a GSST fellowship of Aarhus University. J.-C.S. and B.G. were supported by the European Research Council (ERC-2012-StG-310886-HISTFUNC); C.H.S.-L. and N.R. by the People Programme (Marie Curie Actions) of the European Union's 7th Framework programme (FP7-PEOPLE-2012-IEF-328637 - BiodiversityAltitude); W.D.K. by the Netherlands Organization for Scientific Research (824.15.007) and the University of Amsterdam (starting grant); and H.B. by the Danish National Science Research Council (272-06-0476).

Background Many recent papers have documented the phytochemical and pharmacological bases for the use of palms (Arecaceae) in ethnomedicine. Early publications were based almost entirely on interviews that solicited local knowledge. More recently, ethnobotanically guided searches for new medicinal plants have proven more successful than random sampling for identifying plants that contain biodynamic ingredients. However, limited laboratory time and the high cost of clinical trials make it difficult to test all potential medicinal plants in the search for new drug candidates. The purpose of this study was to summarize and analyze previous studies on the medicinal uses of American palms in order to narrow down the search for new palm-derived medicines. Methods Relevant literature was surveyed and data was extracted and organized into medicinal use categories. We focused on more recent literature than that considered in a review published 25 years ago. We included phytochemical and pharmacological research that explored the importance of American palms in ethnomedicine. Results Of 730 species of American palms, we found evidence that 106 species had known medicinal uses, ranging from treatments for diabetes and leishmaniasis to prostatic hyperplasia. Thus, the number of American palm species with known uses had increased from 48 to 106 over the last quarter of a century. Furthermore, the pharmacological bases for many of the effects are now understood. Conclusions Palms are important in American ethnomedicine. Some, like Serenoa repens and Roystonea regia, are the sources of drugs that have been approved for medicinal uses. In contrast, recent ethnopharmacological studies suggested that many of the reported uses of several other palms do not appear to have a strong physiological basis. This study has provided a useful assessment of the ethnobotanical and pharmacological data available on palms.