The Caatinga (semi-arid region), is an exclusively Brazilian biome. Considering the scarcity of ethnobotanical and ethnopharmacological studies in this region before the year 2000, this study presents data from ethnobotanical expeditions carried out between 1980 and 1990, by the late professor Francisco José de Abreu Matos (1924-2008). The information revealed in this present work are valuable and remained unpublished until now.The objective was to organize, systematize and analyze ethnobotanical and ethnopharmacological data using ethnobotanical analytical techniques. The most cited native species in each use category were selected for literature review of the pharmacological studies related to their ethnomedicinal uses.Revision of the botanical nomenclature led to the botanical confirmation of 272 plants, of which 84 (30.9%) were reclassified. These represented 71 families and 220 genera that were cited 1957 times. 153 (56.3%) of these plant species are native to Brazil, of which 36 (23.4%) are endemic to the Caatinga. The use reports (RU) associated with these plants, according to the body systems (ICPC-2) in decreasing order of UR and the ICF values were respiratory system (93 species, 407 UR, ICF 0.77), digestive system (119 species, 373 UR, ICF 0.68), general and nonspecific symptoms (95 species, 219 UR, ICF 0.58), female genital system (60 species, 184 UR, ICF 0.68), skin (71 species, 156 UR, ICF 0.55), cardiovascular (50 species, 99 UR, ICF 0.50), blood and immune system diseases (46 species, 96 UR, ICF 0.53), urological (44 species, 88 UR, ICF 0.51), musculoskeletal (33 species, 80 UR, ICF 0.60), psychological (21 species, 71 UR, ICF 0.60), while others represent less than 10.0% of the UR. The most cited plants in the disease categories were Dysphania ambrosioides (28), Pombalia calceolaria (28) Hymenaea courbaril (26), Myracrodruon urundeuva (50), Brassica juncea subsp. integrifolia (16), Scoparia dulcis (22), Phyllanthus niruri (14), Egletes viscosa (25), Lippia alba (16), Erythroxylum vacciniifolium (9) and Salvia rosmarinus (21). The most prominent clades of the medicinal plants based on cluster analysis were the Lamiids (Euasterids)-497 UR and the Fabids (Eurosids I) - 468 UR. Association between certain phylogenetic clades and use-category were also observed and discussed.This study demonstrated a new approach in ethnopharmacology by mapping plant usages to diseases prevalent in a community from old ethnobotanical travel reports. In addition to revealing the therapeutic potential of Caatinga species using cluster analysis.
