The relative importance of plant families in traditional medicine in Burkina Faso. The figure shows the difference between a family’s rank regarding total species number and its rank regarding number of species used in traditional medicine. N = total number of species, Fraction TM [%] = percentage of these species used in Traditional medicine, Rank N species = Rank of the family regarding total species number in the country, Rank Fraction TM = rank of the family regarding species used in traditional medicine. The listed families comprise the 12 most species rich families in the country and the 12 plant families most commonly used in TM. Anacardiaceae, Amaranthaceae and Combretaceae are relatively over-used, Convolvulaceae, Cyperaceae, Acanthaceae and Vitaceae are relatively under-used.