Osun, sacred grove, endangered tree species, rare, ecosystems.
A botanical survey of indigenous tree species present in core regions of the Osun sacred grove, Osun state, Nigeria,was conducted. A total of eighty (80) tree species belonging to sixty-six (66) genera and twenty seven (27) families were identified and recorded. The family Fabaceae had the largest number of tree species and accounted for eleven percent (11%) of the total list. It was closely followed by members of the family Sterculiaceae which has a total of ten percent (10%). The high presence of members of Fabaceae and Sterculiaceae may be attributed to variations in soil condition.Some endangered and rare tree species of Nigerian flora like Placodiscus turbinatus Raldk (Sapindaceae) and Albizia intermedia De wild and Th.Dur (Fabaceae) were identified. The grove also has a large representation of economic timber species requiring urgent conservation attention. This study observed that the problem of acculturation and increasing rate of deforestation may pose danger to the continued existence of traditional managed ecosystems. Hence, Ex- situ conservation of tree genetic materials in gene banks was recommended while the Forestry Research Institute of Nigeria (FRIN) is to intensify her effort in the domestication of valuable indigenous tree resources.