- Hits: 5746
Nerium oleander L. 1753
pronounced: NER-ee-um oh-lee-AN-duh
(Apocynaceae – the oleander family)
common names: Oleander
This plant, the only species currently classified in the Nerium genus, has been known to man for thousands of years. It was cultivated in the Nile valley in the time of the Old Kingdom dynasty (3400–2475 BC), and may well have been the ‘bough of a leafy tree’ mentioned in the Old Testament book of Leviticus, which was written about 1400 BC. It is still used in Israel to make temporary shelters for the Feast of Tabernacles. The ancient Greeks knew it as νηρειον (nereion), and the Romans as volubilis. The oleander part of the name comes from the Greek ελαια (elaia), the olive. Why it was named after the olive is not known, although I have read some ingenious suggestions.
All parts of the tree, including the milky white sap, are highly toxic to humans and animals, and the leaves retain their toxicity even after drying out. The burning of trimmings generates toxic fumes. Recently, while I was engaged in conversation with a woman sitting next to me on a bus journey in northern Sydney, we passed through a suburb where the streetscape consisted almost entirely of oleanders, all in full bloom. When I commented on the fact, she told me how she had almost lost her daughter, when she was a toddler, through chewing on an oleander leaf. The child was on the danger list for several days, and, afterwards, the woman and her neighbours had all the oleanders removed from their gardens to guard against further accidents with their children.
Symptoms may include nausea, abdominal pain, lethargy and dizziness, while delayed effects cause slow heart-beat, seizures and coma. The flower perfume may cause respiratory irritation, and skin contact with the sap may cause dermatitis.
Pliny the Elder, writing in his Naturalis Historia in about 77 AD, claimed that, despite its toxicity, oleander was an effective snakebite cure “if taken in wine with rue.”
There are over 400 named cultivars of the oleander, with quite a few colours not found in wild plants. Many of these cultivars have double flowers, and there are a number of dwarf cultivars. The oleander is native to a broad area from Morocco and Portugal eastward throughout the Mediterranean region and to southern Asia as far as Yunnan in southern China. It typically occurs on the banks of streams, especially those that stop running in the dry season. It grows usually from 2 to 6 metres tall. Most dwarf varieties grow only to about 120 cm high with a spread of under 2 m, as against the 5 m height and 4 or more metre spread of most full-sized cultivars. This makes them more suitable for most gardens than the larger varieties. The leaves are in pairs or whorls of three, thick and leathery, dark green, narrow lanceolate. The flowers grow in clusters at the end of each branch, and are pink, white or yellow. They are sometimes, but not always, sweetly scented. The fruit is a long, narrow capsule anything up to about 20 cm long, and dehiscent, releasing many downy seeds.
All oleanders are drought and salt tolerant once established, which makes them a very good plant for Magnetic Island. They will grow in almost any soil, acid or alkaline, even if it has poor drainage, and require very little maintenance. They can be trained as a standard, and even grown in pots for patio use. They do need heavy pruning to develop in these ways. A row of dwarf oleanders will also make a fine screen – they are fast growers. Sometimes suckers will emerge at the base of the plant, and these should be removed so that they do not siphon off too much energy from the main plant.
These decorative shrubs were introduced to the New World by Spanish settlers sometime during in the seventeenth century. There, the pulp surrounding the leaf-veins is eaten by the oleander caterpillar (Syntomeida epilais), a member of the Ctenuchinae, or polka-dot wasp moths. Oleander moths were not imported with the oleander, but are native to the Caribbean. It is thought that the devil's potato (Echites umbellata) was once the main host plant for the caterpillar. Importation of oleanders benefited these pests: they switched host plants and have increased their range. Except for California, the polka-dot wasp moth is now found wherever there are oleanders in the Americas.
In Australia, the Common Australian Crow Butterfly, Euploea core, also called the Oleander Crow, lays its eggs on the oleander, and the lovely silver cocoons are often to be seen. The larvae of the moth Glyphodes onychinalis also use it as a food plant.
Information about medicinal qualities of plants, or about their use as medicines, is for interest only, and is not intended to be used as a guide for the treatment of medical conditions.
Photographs taken at Picnic Bay 2004-2018
Page last updated 10th August 2018