The leaves are dark to bright green, thick and leathery, narrow and lance-shaped. They grow in pairs or whorls of three and are 4 to 10 inches long, depending on the size or variety of the plant.

The summertime 1-to-3-inch flowers are showy with a variety of colors: white, red, pink, salmon, or light yellow. Depending on the plant, flowers may be single or double and are often, but not always, sweetly scented, growing in clusters at the end of each branch.

Oleanders are often used as ornamental plants in landscapes, parks, and along roadsides.

Since they grow quickly, they are perfect for preventing erosion in newly planted areas and for sprucing up new lawns or parks. They’re great for creating screens, informal hedges, or divisions between distinct tracts of land used for disparate purposes. By removing suckers and leaving just a few stems, oleanders can also be formed into very attractive small trees.

The greatest drawback to this very attractive shrub is its extreme toxicity. It should never be used in playgrounds or other areas frequented by small children or pets or pastures for grazing livestock. Every part of the plant is poisonous, fresh or dried, and even the smoke should be avoided when burning cuttings.

Oleander contains numerous toxic compounds and it has been reported that in some cases only a small amount had lethal or near lethal effects. The most significant toxins are oleandrin and neriine, which are “cardiac glycosides” (naturally occurring plant or animal compounds whose actions include both beneficial and toxic effects on the heart). These toxins are very similar to the toxins in foxglove (Digitalis). The toxins are present in all parts of the plant but are most concentrated in the sap. The bark of the plant contains rosagenin which is known for its strychnine-like effects.

Even dried, the plant is toxic. Ten to twenty leaves consumed by an adult can cause an adverse reaction; a single leaf could be lethal to an infant or child. According to the Toxic Exposure Surveillance System (TESS), in 2002 there were 847 known human poisonings in the United States related to oleander.

Oleander poisoning requires immediate medical care. Medical research shows that ingestion can cause both gastrointestinal and cardiac effects. The gastrointestinal effects can consist of nausea and vomiting, excess salivation, abdominal pain, and diarrhea that may or may not contain blood. Cardiac reactions consist of irregular heart rate, sometimes characterized by a racing heart at first that then slows to below normal further along in the reaction. Extremities may become pale and cold due to poor or irregular circulation. Reactions to poisonings from this plant can also affect the central nervous system; these symptoms include drowsiness, tremors, seizures, collapse, and coma leading to death. Oleander sap can cause skin irritations, severe eye inflammation, and allergic reactions characterized by dermatitis.

Inducing vomiting and having the stomach pumped as soon as possible are protective measures to reduce absorption of the toxic compounds; administering charcoal may also help absorb any remaining toxins. Further medical attention may be required and will depend on the severity of the poisoning and symptoms.

Oleander is toxic to pets and livestock as well as humans. About 30 to 40 leaves could deliver a lethal dose to an adult horse. Plant clippings are especially dangerous to horses, as they taste sweet. Symptoms, including severe diarrhea and abnormal heartbeat, develop rapidly and the animal may be found dead with no prior warning.

Although highly toxic in raw form, oleander has been used medicinally for over 3500 years. In the 15th century BC, the Mesopotamians believed in its healing properties; the ancient Babylonians used a mixture of oleander and licorice to treat hangovers; Roman soldiers also took an oleander extract for hangovers. Arab physicians first used oleander as a cancer treatment in the 8th century AD.

In recent centuries, oleander has continued to be used in folk remedies and in commercial preparations. In Turkey in 1966, Doctor H. Z. Ozel rediscovered a centuries-old oleander extract remedy which he later refined and patented as Anvirzel. It has been used with great success for the past 40 years in treating cancer and other cell proliferative diseases. Nerium oleander extract and Anvirzel have been the subject of numerous trials and studies, most notably those led by MD Anderson researcher Doctor Robert Newman, and Anvirzel has passed US FDA phase I trials.

In European studies in the 1980s, the nerium oleander extract was found to have six times the immune stimulating activity of the most powerful patented immune stimulators.
The home-remedy version of nerium oleander extract is modeled after Doctor Ozel's patent for Anvirzel and is called "oleander soup."

This remedy is used to treat cancer, hepatitis-C, psoriasis, HIV and other conditions. When further condensed and made into a skin cream, the remedy is used to get rid of warts, moles, age spots and pre-cancerous lesions. This home remedy is not recommended without consultation and close supervision of an experienced herbalist and/or physician due to the high toxicity of oleander and the inherent danger in handling the plant and ingesting its toxins.

So although beautiful, hardy, and easy to grow in and around the Verde Valley, care must be taken in when and where to plant oleander. It can add a lovely focal point to your yard, but can be deadly to those unaware—or unable to understand—its drawbacks.