The present study characterized the plant diversity of oil palm plantations in function of farming practices and their ages. The plant diversity of 7, 11 and 14 years old oil palm plantations evolving in different farming practices was inventoried using 1m x 1m quadrats for herbaceous species and the 20 m wide transects for woody species. The results obtained show that these stands are not very diversified: P7 presents 37 species, 34 genera and 27 families; P11, 27 species 26 genera, 18 families and P14, 31 species, 28 genera, 19 families. Only Ng13 had woody species individualized into trees and shrubs. The combination of manual and chemical weeding and irregular fertilization promotes the diversity of herbaceous species in the different stands. Age and farming practices influence the plant diversity of the stands.