Background: The world population use medicinal plants for treating diseases in forms of drug developments also traditional medicinal specially developing countries. The economic growth and cultural changes threaten the traditional lifestyle of local people. The aim of the study is to investigate medicinal plants and associated indigenous knowledge.
Methods: Ethnobotanical data were obtained using semi-structured interviews, focus group discussion and market survey. Data were analyzed by descriptive statistics, informant consensus factor, preference ranking and Direct matrix ranking using Microsoft Excel and Statistical Package for Social Science Version 20.
Results: Ethnomedicinal use of 136 medicinal plant species belonging to 117 genera and 63 families wereidentified and documented. The highest number of medicinal plants was used in midland kebele(74 species). Out of total medicinal plants 66 (48.53%) species were reported to treat human aliments only. Most of the medicinal plants harvested were herbs (37.50%), followed by trees (36.76%) and the least was lianas (0.74%). A Pearson correlation test indicated a positive and significant difference between age of informants and number of medicinal plant species cited, and negative and significant difference between level of education and number of medicinal plant species cited. The result indicates that there was significant difference between male and female informants in their knowledge of medicinal plants, and there was significant different between number of medicinal plants reported by key informants and household respondents. Cordia africana ranked first as a multipurpose medicinal plant. Agricultural expansion (41.96%) stood first as a factor threatening medicinal plants.
Conclusion: The highest numbers of MPs were used in Sire Morose kebele (midland), but collection was not restricted only to their locality the move other kebeles to harvest MPs. In the study area elders have better knowledge of medicinal plant than younger and as people educate their knowledge on medicinal plants decrease.This implies that in study area there is potential indigenous knowledge but we are going loss this traditional knowledge if did not develop means transferring this to next generation. To support local people effort on in-situ conservation and ex-situ conservation needed