Nerium oleander, commonly known as Oleander or rosebay, is a shrub or small tree cultivated worldwide in temperate and subtropical areas as an ornamental and landscaping plant.

It grows up to 20 feet tall and is commonly grown as a shrub but can be trained into a small tree with a single trunk. It is tolerant of both drought and inundation but not prolonged frost. White, pink, or red five-lobed flowers grow in clusters year-round, peaking during the summer. The fruit is a long, narrow pair of follicles that split open at maturity to release downy seeds.

Oleander is the only species remaining in the ancient genus Nerium. Although it is believed to have originated from the Mediterranean, the true origin of this beautiful flowering plant is mysterious because it has been cultivated and spread worldwide since ancient times. Oleander is extremely toxic to humans, but the Bedouin of Egypt historically used it to treat cancer.

Source: Wikipedia