Plants are important resources in healthcare and for producing pharmaceutical drugs. Pharmacological and phytochemical characterization contributes to both the safe use of herbal medicines and the identification of leads for drug development. However, there is no recent assessment of the proportion of plants used in ethnomedicine that are characterized in this way. Further, although it is increasingly apparent that plants used in ethnomedicine belong to preferred phylogenetic lineages, it is not known how this relates to the focusing of research effort. Here we identify species and lineages rich in ethnomedicinal use and develop methods to describe how well they are known pharmacologically and/or phytochemically. We find 50% of plant species of the family Leguminosae used in ethnomedicine in Brazil, a geographical area where plants are an important part of healthcare, have been the focus of either phytochemical screening or testing for biological activity. Plant species which have more use reports are studied significantly more often (p < 0.05). Considering the taxonomic distribution of use, 70% of genera that include species with ethnomedicinal use have been studied, compared to 19% of genera with no reported use. Using a novel phylogenetic framework, we show that lineages with significantly greater numbers of ethnomedicinal species are phylogenetically over-dispersed within the family, highlighting the diversity of species used. “Hotnode clades” contain 16% of species but 46% of ethnomedicinally-used species. The ethnomedicinal species in hotnode clades have more use reports per species (p < 0.05), suggesting they are more frequently used. They are also more likely to be characterized pharmacologically and/or phytochemically. Research focus has followed traditional use by these measures, at least for these Brazilian plants, yet ethnomedicinal species yielding candidate drugs, raising public health concerns and more intensively studied lie outside of the hotnode clades.

The use of herbarium specimens as vouchers to support ethnobotanical surveys is well established. However, herbaria may be underutilized resources for ethnobotanical research that depends on the analysis of large datasets compiled across multiple sites. Here, we compare two medicinal use datasets, one sourced from published papers and the other from online herbaria to determine whether herbarium and published data are comparable and to what extent herbarium specimens add new data and fill gaps in our knowledge of geographical extent of plant use. Using Brazilian legumes as a case study, we compiled 1400 use reports from 105 publications and 15 Brazilian herbaria. Of the 319 species in 107 genera with cited medicinal uses, 165 (51%) were recorded only in the literature and 55 (17%) only on herbarium labels. Mode of application, plant part used, or therapeutic use was less often documented by herbarium specimen labels (17% with information) than publications (70%). However, medicinal use of 21 of the 128 species known from only one report in the literature was substantiated from independently collected herbarium specimens, and 58 new therapeutic applications, 25 new plant parts, and 16 new modes of application were added for species known from the literature. Thus, when literature reports are few or information-poor, herbarium data can both validate and augment these reports. Herbarium data can also provide insights into the history and geographical extent of use that are not captured in publications.Electronic supplementary materialThe online version of this article (doi:10.1007/s12231-017-9367-1) contains supplementary material, which is available to authorized users.