Oleander (Nerium oleander) is an evergreen shrub belonging to the family Apocynaceae. It is characterized by its beautiful flowers and its relative ability to tolerate heat and drought, making it widely cultivated as an ornamental plant in gardens and along roadsides. The plant has branched stems that can reach several meters in height, while its leaves are long, narrow, relatively thick, and dark green. The flowers are produced in inflorescences at the ends of the branches and vary in color, including white, pink, and red, depending on the cultivar. The flowers are one of the main reasons for using oleander in landscaping and ornamental gardens. The plant contains a number of biologically active chemical compounds, most notably cardiac glycosides such as oleandrin, which have strong physiological effects. For this reason, all parts of the oleander plant are toxic if ingested, and the plant should be handled with caution and should not be used for medicinal purposes without professional supervision. These compounds form part of the plant’s chemical defense system, helping protect it from herbivores. Despite its toxicity, oleander has important aesthetic and ecological value, and its flowers can provide food sources for some insects. Its ability to tolerate harsh environmental conditions also makes it suitable for cultivation in some dry urban areas. Oleander provides a clear example of the importance of defensive compounds in plants and the relationship between plant characteristics, environmental adaptation, and ornamental use. Therefore, it represents a suitable subject for study in botany and phytochemistry. Al-Mustaqbal University – The First University in Iraq