Medicinal plants of Chinese Pharmacopoeia and Daodi:Insights fromphylogeny and biogeography

Objective: The Chinese Pharmacopoeia(2015) includes 584 plant medicines, of which 284 also contain high quality subsets, so called "Daodi" components, where Daodi denotes superior clinical properties compared to non-Daodi counterparts despite being sourced from the same species. Commercial and clinical drivers of selection for Daodi have been described elsewhere. Our objective is to investigate the overall composition of Daodi to determine in what ways medicines with Daodi as a whole differ from the other plants of the Chinese Pharmacopoeia. A further objective is to characterise the Chinese Pharmacopoeia and Daodi in terms of the plant species including their traits and distribution.Methods: We used trait analysis to identify whether Daodi species were significantly different from the remaining Chinese Pharmacopoeia plant species in any traits. We used biogeographic methods and an existing classification of Daodi into 10 regions to identify spatial patterns amongst the species. Regression and binomial analyses were used to test for over-and under-use of plant families and endemic species.Preferences for lineages were visualized using phylogenetic mapping.Results: We found that Daodi species(species with any Daodi subset) were more likely to be roots that are "hot" or "warm", and less likely to be "oxic", according to traditional Chinese medicine(TCM) concepts. Roots were over-represented in the Bei region, and whole plants over-represented in Guang. Both the Chinese Pharmacopoeia and Daodi indicated preferences for families not common in previously studied ethnopharmacopoeias, and fewer endemic species were represented than expected by chance.Conclusion: Using the phylogenetic and biogeographical methods, we highlighted patterns of plant use,and the biological characters of Daodi medicinal plants. Our study points towards cultural preferences in need of scientific explanation.