Oleander (Nerium)

Description

“Pet poisonous” – Toxic parts: leaves Nerium oleander is a shrub or small tree in the dogbane family Apocynaceae, toxic in all its parts. It is the only species currently classified in the genus Nerium. It is most commonly known as nerium or oleander, from its superficial resemblance to the unrelated olive Olea. It is so widely cultivated that no precise region of origin has been identified, though southwest Asia has been suggested. The ancient city of Volubilis in Morocco may have taken its name from the Berber name alili or oualilt for the flower. Oleander is one of the most poisonous commonly grown garden plants. Oleander grows to 2–6 m (6.6–19.7 ft) tall, with erect stems that splay outward as they mature; first-year stems have a glaucous bloom, while mature stems have a grayish bark. The leaves are in pairs or whorls of three, thick and leathery, dark-green, narrow lanceolate, 5–21 cm (2.0–8.3 in) long and 1–3.5 cm (0.39–1.38 in) broad, and with an entire margin filled with minute reticulate venation web typical of eudicots. Leaves are light green and very glossy when young, before maturing to a dull dark green/greenish gray. The flowers grow in clusters at the end of each branch; they are white, pink to red,[Note 2] 2.5–5 cm (0.98–1.97 in) diameter, with a deeply 5-lobed fringed corolla round the central corolla tube. They are often, but not always, sweet-scented. The fruit is a long narrow pair of follicles 5–23 cm (2.0–9.1 in) long, which splits open at maturity to release numerous downy seeds. Drugs derived from N. oleander have been investigated as a treatment for cancer, but have failed to demonstrate clinical utility. According to the American Cancer Society, the trials conducted so far have produced no evidence of benefit, while they did cause adverse side effects. Oleander has historically been considered a poisonous plant because some of its compounds may exhibit toxicity, especially to animals, when consumed in large amounts. Among these compounds are oleandrin and oleandrigenin, known as cardiac glycosides, which are known to have a narrow therapeutic index and can be toxic when ingested. Toxicity studies of animals administered oleander extract concluded that rodents and birds were observed to be relatively insensitive to oleander cardiac glycosides. Other mammals, however, such as dogs and humans, are relatively sensitive to the effects of cardiac glycosides and the clinical manifestations of "glycoside intoxication". In reviewing oleander toxicity cases seen in-hospital, Lanford and Boor[38] concluded that, except for children who might be at greater risk, "the human mortality associated with oleander ingestion is generally very low, even in cases of moderate intentional consumption (suicide attempts)". In 2000, a rare instance of death from oleander poisoning occurred when two toddlers adopted from a Siberian orphanage ate the leaves from a neighbor's shrub in El Segundo, California. A spokesman for the Los Angeles County Coroner's office stated that it was the first instance of death connected to oleander in the county, and a toxicologist from the California Poison Control Center said it was the first instance of death he had seen recorded. Because oleander is extremely bitter, officials speculated that the toddlers had developed a condition caused from malnutrition, Pica, which causes people to eat otherwise inedible material.