An investigation of the plant diversity of Idanre Hill was carried out using quadrant sampling technique and an extensive assessment of plant species found along different gradients namely, mountain top, midpoint and foothill. Quadrat size of 10m2 was randomly placed in 10 points on each elevation, followed by qualitative and quantitative vegetation description. Life form classifications were carried out and the conservation status of the species was evaluated using the International Union of Conservation of Nature (IUCN) Redlist v. 2016- 2. A total of 50 taxa belonging to 49 genera and 36 families were encountered during the study. The dominant genus was Citrus represented with 2 species while the dominant family was Asteraceae represented with 5 species and according to the life form was a herb as it covers 34% of the entire taxa encountered. On the mountain top, a total of 25 species belonging to 25 genera and 18 families were recorded while a total of 28 species belonging to 28 genera and 23 families on the midpoint, and total of 45 species belonging to 43 genera and 33 families were recorded at the foothill. The study revealed that the foot-hill had the highest number of species (45), genera (43) and family. Diversity index revealed the highest diversity of species in the foothill with Margalef, Shannon wiener and Simpson’s index values of 9.025, 3.426 and 0.9538 respectively while the mountain top vegetation had the highest dominance and evenness value of 0.0537 and 0.8427 respectively. This study explored the effects of elevation and elevation topography on plant species diversity and also studied the contribution of each of the different mechanisms that determine the structure of vegetation and plant diversity on hills.
Key Words: Plants species, Diversity, Mountain site, Environment, Idanre hill