Nerium oleander L. (Apocynaceae), commonly known as oleander and rosebay, is a shrub cultivated worldwide in temperate and subtropical areas as an ornamental and landscaping plant. Oleander has a wide range of both internal and external medicinal uses. In the epidermis section, the stomata scattering on the lower surface is the type called unifacial, wherein the stomatal type is sunken. Distinguishing it is difficult in the surface view because of the epidermis and cuticle layer thickness. However, one can distinguish it in the cross-section of the leaf, which is an important taxonomic characteristic that separates this species from other species in the genus. The oleander plants varied in the cross-sectional shapes of their stems. Wild oleander plants showed higher contents of phenols, tannins, cardiac glycosides, and saponins than cultivated plants. Leaf extract evaluation serves as inhibitory agents for selected Gram-negative (Acinetobacter baumannii and Escherichia coli) and Gram-positive (Staphylococcus aureus and Streptococcus faecalis) pathogenic bacteria isolates. In N. oleander, the antibacterial efficacy of ethanolic and aqueous leaf extracts differed among bacterial genera. Both aqueous and ethanolic leaf extracts were effective against E. coli; however, they did not show any inhibitory activity against other bacterial strains, such as A. baumannii, S. aureus, and St. faecalis.
Anatomical evaluation, antibacterial activity, Apocynaceae, aqueous and alcoholic leaf extract, oleander
The latest research, comprising pharmacognostic and anatomy of the oleander (N. oleander L.), will help authenticate information about its medicinal values and species identification. Additionally, antibacterial activity investigation of N. oleander leaf extract against some pathogenic bacteria genera has also been successful.