Nerium

Nerium oleander, the oleander, is a shrub or small tree native to the Mediterranean region east to southern Asia, from Morocco and Portugal east to India and Myanmar; the Flora of China also cites it as native in Yunnan in China. It is the only species currently classified in the genus Nerium, belonging to subfamily Apocynoideae of the dogbane family Apocynaceae. It is also cultivated widely in temperate and subtropical areas as an introduced ornamental and landscaping plant. It is tolerant to both drought and inundation, but not to prolonged frost. It is a highly poisonous plant but its bitterness renders it unpalatable to humans and most animals, so poisoning cases are rare and the general risk for human mortality is low. Ingestion of larger amounts may cause nausea, vomiting, excess salivation, abdominal pain, bloody diarrhoea and irregular heart rhythm. Prolonged contact with sap may cause skin irritation, eye inflammation and dermatitis.

Nerium oleander, the oleander, is a shrub or small tree native to the Mediterranean region east to southern Asia, from Morocco and Portugal east to India and Myanmar; the Flora of China also cites it as native in Yunnan in China. It is the only species currently classified in the genus Nerium, belonging to subfamily Apocynoideae of the dogbane family Apocynaceae. It is also cultivated widely in temperate and subtropical areas as an introduced ornamental and landscaping plant. It is tolerant to both drought and inundation, but not to prolonged frost. It is a highly poisonous plant but its bitterness renders it unpalatable to humans and most animals, so poisoning cases are rare and the general risk for human mortality is low. Ingestion of larger amounts may cause nausea, vomiting, excess salivation, abdominal pain, bloody diarrhoea and irregular heart rhythm. Prolonged contact with sap may cause skin irritation, eye inflammation and dermatitis. ==Description== east of Ouarzazate in Morocco]] Oleander grows to tall, with erect stems that splay outward as they mature; first-year stems have a glaucous bloom, while mature stems have a greyish bark. It is most commonly grown in its natural shrub form, but can be trained into a small tree with a single trunk. The leaves are in pairs or whorls of three, thick and leathery, dark-green, narrow lanceolate, long and broad, and with an entire margin filled with minute reticulate venation web typical of eudicots. The leaves are light green and very glossy when young, maturing to a dull dark green. The flowers grow in clusters at the end of each branch; they are diameter, pink, with a deeply 5-lobed fringed corolla round the central corolla tube in natural wild plants. White to dark red, larger (to 5 cm diameter), and double-flowered, cultivars are also common in cultivation. They are often, but not always, sweet-scented. The fruit is a long narrow pair of follicles long, which splits open at maturity to release numerous downy seeds. ==Distribution and habitat== in Libya]] Nerium oleander is either native or naturalised to a broad area from northwest Africa through the Mediterranean region and warmer areas of the Black Sea region, Arabian Peninsula, southern Asia, and as far east as Yunnan in southern parts of China. It can be found in tropical, subtropical, and temperate regions. The plant typically occurs in dry locations with a lot of sun near stream beds where it can alternatively tolerate long seasons of drought and inundation from winter rains. ==Ecology== Some invertebrates are known to be unaffected by oleander toxins, and feed on the plants. 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 fibres. Larvae of the common crow butterfly (Euploea core) and oleander hawk-moth (Daphnis nerii) also feed on oleanders, and they retain or modify toxins, making them unpalatable to potential predators such as birds, but not to other invertebrates such as spiders and wasps. The flowers require insect visits to set seed, and seem to be pollinated through a deception mechanism. 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. They therefore receive very few visits, as typical of many rewardless flower species. Fears of honey contamination with toxic oleander nectar are therefore unsubstantiated. ===Leaf scorch=== in Phoenix]] A bacterial disease known as (Xylella fastidiosa subspecies sandyi) has become a serious threat to the shrub since it was first noticed in Palm Springs, California, in 1992. 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. The culprit is a bacterium which is spread via insects (the glassy-winged sharpshooter primarily) which feed on the tissue of oleanders and spread the bacteria. This inhibits the circulation of water in the tissue of the plant, causing individual branches to die until the entire plant is consumed. Symptoms of leaf scorch infection may be slow to manifest themselves, but it becomes evident when parts of otherwise healthy oleanders begin to yellow and wither, as if scorched by heat or fire. 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. As such it can be difficult to identify at first because gardeners may mistake the symptoms for those of drought stress or nutrient deficiency. Pruning out affected parts can slow the progression of the disease but not eliminate it. This malaise can continue for several years until the plant completely dies; there is no known cure. The best method for preventing further spread of the disease is to prune infected oleanders to the ground immediately after the infection is noticed. The responsible pathogen was identified as the subspecies sandyi by Purcell et al., 1999. ==Cultivation== Beyond the traditional Mediterranean and subtropical range of oleander, the plant can also be cultivated in mild oceanic climates with the appropriate precautions. It is grown without protection in warmer areas in Switzerland, southern and western Germany and southern England and can reach great sizes in London and to a lesser extent in Paris due to the urban heat island effect. This is also the case with North American cities in the Pacific Northwest like Portland, Seattle, and Vancouver. Plants may suffer damage or die back in such marginal climates during severe winter cold but will rebound from the roots. , with white flowers only]] On the East Coast of the United States, it grows as far north as Virginia Beach, while in California and Texas miles of oleander shrubs are planted on median strips. There are estimated to be 25 million oleanders planted along highways and roadsides throughout the state of California. Because of its durability, oleander was planted prolifically on Galveston Island in Texas after the disastrous Hurricane of 1900. They are so prolific that Galveston is known as the 'Oleander City'; an annual oleander festival is hosted every spring. Moody Gardens in Galveston hosts the propagation program for the International Oleander Society, which promotes the cultivation of oleanders. New cultivars are hybridised and grown on the Moody Gardens grounds, encompassing every named cultivar. ===History=== . ]] Nerium oleander has a history of cultivation going back millennia, especially amongst the great ancient civilisations of the Mediterranean Basin. Some scholars believe it to be the rhodon (rose), also called the "Rose of Jericho", mentioned in apocryphal writings (Sirach 24:14) dating between 450 and 180 BC. The ancient Greeks had several names for the plant, including rhododaphne, nerion, rhododendron and rhodon. Pliny the Elder said that the Romans had no Latin word for the plant, but used the Greek terms instead. 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. The Egyptians apparently called it scinphe, the North Africans rhodedaphane, and the Lucanians (a southern Italic people) icmane. Both Pliny and Dioscorides stated that oleander was an effective antidote to venomous snake bites if mixed with rue and drunk. However, both rue and oleander are poisonous themselves, and consuming them after a venomous snake bite can accelerate the rate of mortality and increase fatalities. 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. According to this theory, the symptoms of the Pythia's trances (enthusiasmos) correspond to either inhaling the smoke of or chewing small amounts of oleander leaves, often called by the generic term laurel in Ancient Greece, which led to confusion with the bay laurel that ancient authors cite. In his book Enquiries into Plants of circa 300 BC, Theophrastus described (among plants that affect the mind) a shrub he called onotheras, which modern editors render oleander: "the root of onotheras [oleander] administered in wine", he alleges, has a beneficial effect on mood: The root of onotheras [oleander] administered in wine makes the temper gentler and more cheerful. The plant has a leaf like that of the almond, but smaller, and the flower is red like a rose. The plant itself (which loves hilly country) forms a large bush; the root is red and large, and, if this is dried, it gives off a fragrance like wine. In another mention, of "wild bay" (Daphne agria), Theophrastus appears to refer to the same shrub. Oleander was a very popular ornamental shrub in Roman peristyle gardens; it is one of the plants most frequently depicted on murals in Pompeii and elsewhere in Italy. These murals include the famous garden scene from the House of Livia at Prima Porta outside Rome, and those from the House of the Wedding of Alexander and the Marine Venus in Pompeii. Carbonised fragments of oleander wood have been identified at the Villa Poppaea in Oplontis, buried by the eruption of Mount Vesuvius in 79 AD. They were found to have been planted in a decorative arrangement with citron trees (Citrus medica) alongside the villa's swimming pool. Herbaria of oleander cultivars are compiled and held at the Smithsonian Institution in Washington, D.C., and at Moody Gardens in Galveston, Texas. ==Culture== ==Gallery== File:Nerium oleander peach.jpg|alt=Peach coloured flowers File:Nerium Oleander (yellow, unusual--may be Sue Hawley Oakes).jpg|An unusual yellow-flowered cultivar. Cultivated in Galveston, Texas File:Nerium Oleander(Red).jpg|alt=Red flower File:Oleander Capsule Opens.jpg|Follicle spreading seeds File:Nerium oleander pink.jpg|alt=Pink flowers and leaves File:RoscheiderhofHerbst2018H3a.jpg|alt=Small tree File:Flowers of Nerium oleander in West Bengal, India.jpg|alt=Flowers of N. oleander in West Bengal|N. oleander in West Bengal File:OleaUA2013.jpg| Closed buds of an oleander shrub near Yalta, Ukraine ==See also== Cascabela thevetia (yellow oleander) List of ineffective cancer treatments List of plants poisonous to equines List of poisonous plants Tibesti-Jebel Uweinat montane xeric woodlands ==External links== Information on Oleander toxicity. International Oleander Society. Retrieved on 2009-07-27. Plants of North Africa. Jardí Botànic de Barcelona Retrieved on 2009-07-27. Medical problems caused by plants: Plant Toxins, Cardiac Glycosides. Erwin, Van den Enden. 2004. Illustrated Lecture Notes on Tropical Medicine. Prince Leopold Institute of Tropical Medicine. Retrieved on 2009-07-27. Legend of Oleander-poisoning at Campfire. Snopes. Retrieved on 2009-07-27. Distribution over the world, N. oleander, University of Helsinki

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