AbstractThe comparative anatomical study of ten species ofSidaoccurring in Nigeria was carried out. The anatomical characters of the matured leaf were examined in order to substantiate taxonomic boundaries between the species. The species possess distinctive anatomical characters which indicate close relationship. However, there is a range in the trichome form; the glandular and non‐glandular; nine kinds of trichomes were recorded. The anatomical characters observed in this study supported the reduction ofS. acutaandS. stipulatatoS. acutasubsp.acutaandS. acutasubsp.carpinifoliarespectively. However, the previous taxonomic decision to splitt theS. rhombifoliacomplex into three subspecies was not supported on anatomical ground