Background: Hot-cold conception is important for plant-disease relationships in peasant communities, where introduced species acquire medicinal uses and are more available in anthropocentric systems than native; how these are selected is studied with indices, hypotheses that contribute to theories are rarely tested. Hypotheses: There will be more medicinal introduced species that will have more versatility than native ones; home-gardens will have more availability of them than the forest. Study site and dates: San Pedro Topiltepec (SPT), San Andrés Nuxiño (SAN), Oaxaca, September 2015-March 2017. Methods: Medicinal flora and its uses were inventoried by community, recording availability (socioecological system) and status (native/introduced) by species. Informant consensus factor and relative value estimated information similarity among informants; use value (UV) indicated species versatility. Hot-cold conditions were recorded by species and disease. Results: Species and diseases were 64 (75 % native, 25 % introduced) and 134 in SAN, 81 (52 % native, 48 % introduced) and 177 in SPT, respectively. In SAN 58 % species were available in forests, in SPT 62 % species were available in home gardens. UV was higher for native plants in SAN and for introduced plants in SPT. Hot-cold dichotomy influenced selection of medicinal plants in both communities. Conclusions: Both communities belong the same ethnicity, select medicinal plants differently. SAN uses a higher proportion of native plants, forests have higher species availability, native plants are the most versatile. SPT uses similar proportions of native and introduced plants, home gardens have more availability, introduced plants are the most versatile.