Ingestion of larger amounts may cause nausea, vomiting, excess salivation, abdominal pain, bloody diarrhea and irregular heart rhythm.

The leaves are in pairs or whorls of three, thick and leathery, dark-green, narrow lanceolate, 5–21 centimetres (2–8 inches) long and 1–3.5 cm (3⁄8–1+3⁄8 in) broad, and with an entire margin filled with minute reticulate venation web typical of eudicots.

The word oleander appears as far back as the first century AD, when the Greek physician Pedanius Dioscorides cited it as one of the terms used by the Romans for the plant.

[15][16][17][18] It typically occurs around stream beds in river valleys, where it can alternatively tolerate long seasons of drought and inundation from winter rains.

On the East Coast of the US, it grows as far north as Virginia Beach, while in California and Texas miles of oleander shrubs are planted on median strips.

Caterpillars of the polka-dot wasp moth (Syntomeida epilais) feed specifically on oleanders and survive by eating only the pulp surrounding the leaf-veins, avoiding the fibers.

The showy corolla acts as a potent advertisement to attract pollinators from a distance, but the flowers are nectarless and offer no reward to their visitors.

A bacterial disease known as oleander leaf scorch (Xylella fastidiosa subspecies sandyi[31]) has become a serious threat to the shrub since it was first noticed in Palm Springs, California, in 1992.

[32] The disease has since devastated hundreds of thousands of shrubs mainly in Southern California, but also on a smaller scale in Arizona, Nevada and Texas.

Die-back may cease during winter dormancy, but the disease flares up in summer heat while the shrub is actively growing, which allows the bacteria to spread through the xylem of the plant.

Some scholars believe it to be the rhodon (rose), also called the 'Rose of Jericho', mentioned in apocryphal writings (Ecclesiasticus XXIV, 13)[36] dating back to between 450 and 180 BC.

[39] Pedanius Dioscorides states in his 1st century AD pharmacopeia De Materia Medica that the Romans used the Greek rhododendron but also the Latin Oleander and Laurorosa.

A 2014 article in the medical journal Perspectives in Biology and Medicine posited that oleander was the substance used to induce hallucinations in the Pythia, the female priestess of Apollo, also known as the Oracle of Delphi in Ancient Greece.

[42] Oleander was a very popular ornamental shrub in Roman peristyle gardens; it is one of the flora most frequently depicted on murals in Pompeii and elsewhere in Italy.

[43] Carbonized fragments of oleander wood have been identified at the Villa Poppaea in Oplontis, likewise buried by the eruption of Mount Vesuvius in 79 AD.

[22] Oleander is a vigorous grower in warm subtropical regions, where it is extensively used as an ornamental plant in parks, along roadsides and in private gardens.

The toxicity of oleander renders it deer-resistant and its large size makes for a good windbreak – as such it is frequently planted as a hedge along property lines and in agricultural settings.

The plant is tolerant of poor soils, intense heat, salt spray, and sustained drought – although it will flower and grow more vigorously with regular water.

Although it does not require pruning to thrive and bloom, oleander can become unruly with age and older branches tend to become gangly, with new growth emerging from the base.

Free-flowering varieties like 'Petite Salmon' or 'Mont Blanc' require no period of rest and can flower continuously throughout the year if the weather remains warm.

They require frequent heavy watering and fertilizing as compared to being planted in the ground, but oleander is nonetheless an ideal flowering shrub for patios and other spaces with hot sunshine.

Placing them in a space with central heating and poor air flow can make them susceptible to a variety of pests – aphids, mealybugs, oleander scale, whitefly and spider mites.

Over 400 cultivars have been named, with several additional flower colors not found in wild plants having been selected, including yellow, peach and salmon.

Isadore Dyer' (deep pink), 'Mathilde Ferrier' (yellow) or 'Mont Blanc' (white) are enjoyed for their large, rose-like blooms and strong fragrance.

[48] Toxicity studies of animals concluded that birds and rodents were observed to be relatively insensitive to the administered oleander cardiac glycosides.

"[54] In 2000, a rare instance of death from oleander poisoning occurred when two toddlers adopted from an orphanage ate the leaves from a neighbor's shrub in El Segundo, California.

Therefore, clinical features of oleander poisoning are similar to digoxin toxicity and include nausea, diarrhea, and vomiting due to stimulation of the area postrema of the medulla oblongata, neuropsychic disorders, and pathological motor manifestations.

[citation needed] Digoxin immune fab is the best way to cure an oleander poisoning if inducing vomiting has no or minimal success, although it is usually used only for life-threatening conditions due to side effects.

Many of the oleander relatives, such as the desert rose (Adenium obesum) found in East Africa, have similar leaves and flowers and are equally toxic.

Often told as a true and local event, typically an entire family, or in other tellings a group of scouts, succumbs after consuming hot dogs or other food roasted over a campfire using oleander sticks.