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Nerium oleander ( ), commonly known as oleander or rosebay, is a shrub or small tree cultivated worldwide in temperate and subtropical areas as an ornamental and landscaping plant. It is the Monotypic taxon currently classified in the genus Nerium, belonging to subfamily Apocynoideae of the dogbane family Apocynaceae. It is so widely cultivated that no precise region of origin has been identified, though it is usually associated with the Mediterranean Basin.
Nerium grows to tall. It is most commonly grown in its natural shrub form, but can be trained into a small tree with a single trunk. It is tolerant to both drought and inundation, but not to prolonged frost. White, pink or red five-lobed flowers grow in clusters year-round, peaking during the summer. The fruit is a long narrow pair of follicles, which splits open at maturity to release numerous downy seeds.
Nerium is a 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 diarrhea and irregular heart rhythm. Prolonged contact with sap may cause skin irritation, eye inflammation and dermatitis.
The flowers grow in clusters at the end of each branch; they are white, pink to red,The "Yellow Oleander" is Cascabela thevetia diameter, with a deeply 5-lobed fringed corolla round the central corolla tube. They are often, but not always, sweet-scented.In the past, scented plants were sometimes treated as the distinct species N. odorum, but the character is not constant and it is no longer regarded as a separate taxon. The fruit is a long narrow pair of follicles long, which splits open at maturity to release numerous downy seeds.
The origins of the species name are disputed. 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. Merriam-Webster believes the word is a Medieval Latin corruption of Late Latin names for the plant: arodandrum or lorandrum, or more plausibly rhododendron (another Ancient Greek name for the plant), with the addition of olea because of the superficial resemblance to the Olea europea tree ( Olea europea)Cf. oleaster Another theory posited is that oleander is the Latinized form of a Greek compound noun: οllyo (ὀλλύω) 'I kill', and the Greek noun for man, aner, genitive andros (ἀνήρ, ἀνδρός). ascribed to oleander's toxicity to humans.
The etymological association of oleander with the bay laurel has continued into the modern day: in France the plant is known as "laurier rose", while the Spanish term, "Adelfa", is the descendant of the original Ancient Greek name for both the bay laurel and the oleander, daphne, which subsequently passed into Arabic usage and thence to Spain.
The ancient city of Volubilis in Morocco may have taken its name from the Berber language name alili or oualilt for the flower.
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 . 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 varieties are hybridized and grown on the Moody Gardens grounds, encompassing every named variety.
Beyond the traditional Mediterranean and subtropical range of oleander, the plant can also be cultivated in mild 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.
The flowers require insect visits to set seed, and seem to be pollination 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.Shmida, A., Ivri, Y., and Cohen, D. The enigma of the oleander. Eretz VeTeva, January–February 1995 (in Hebrew). Fears of honey contamination with toxic oleander nectar are therefore unsubstantiated.
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.
The ancient Greeks had several names for the plant, including rhododaphne, nerion, rhododendron and rhodon. Pliny confirmed 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 Ruta graveolens 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 laurus nobilis 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:
In another mention, of "wild bay" ( Daphne agria), Theophrastus appears to intend the same shrub.
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. 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.
Carbonization fragments of oleander wood have been identified at the Villa Poppaea in Oplontis, likewise 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.
herbarium of oleander varieties are compiled and held at the Smithsonian Institution in Washington, D.C., and at Moody Gardens in Galveston, Texas.
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. For this reason gardeners are advised to prune mature shrubs in the autumn to shape and induce lush new growth and flowering for the following spring. Unless they wish to harvest the seeds, many gardeners choose to prune away the seedpods that form on spent flower clusters, which are a drain on energy. Propagation can be made from cuttings, where they can readily root after being placed in water or in rich organic potting material, like compost.
In Mediterranean climates oleanders can be expected to bloom from April through October, with the heaviest bloom usually occurring between May and June. 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.
In cold winter climates, oleander is a popular summer potted plant readily available at most nurseries. 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. During the winter they should be moved indoors, ideally into an unheated greenhouse or basement where they can be allowed to go dormant. Once they are dormant they require little light and only occasional watering. 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.
Toxicity studies of animals concluded that birds and rodents were observed to be relatively insensitive to the administered 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".
It is also hazardous to animals such as sheep, , cattle, and other grazing animals, with as little as 100 g being enough to kill an adult horse. Plant clippings are especially dangerous to horses, as they are sweet. In July 2009, several horses were poisoned in this manner from the leaves of the plant. Symptoms of a poisoned horse include severe diarrhea and abnormal heartbeat. This is aptly reflected in the plant's Sanskrit name aśvamāra (अश्वमार), a compound of aśva "horse" and māra "killing".
In reviewing oleander toxicity cases seen in-hospital, Lanford and Boor 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 an orphanage ate the leaves from a neighbor's shrub in El Segundo, California. Because oleander is extremely bitter, officials speculated that the toddlers had developed a condition caused by malnutrition, pica, which causes people to eat otherwise inedible material.
The severity of the intoxication can vary based on the quantity ingested and an individual's physiological response, as well as the time of symptom onset after oleander ingestion: they can rapidly occur after drinking teas prepared with oleander leaves or roots or develop more slowly due to the ingestion of unprepared plant parts.
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.
Drying of plant materials does not eliminate the toxins. There is a wide range of toxins and secondary compounds within oleander, and care should be taken around this plant due to its toxic nature. Different names for oleander are used around the world in different locations, so, when encountering a plant with this appearance, regardless of the name used for it, one should exercise great care and caution to avoid ingestion of any part of the plant, including its sap and dried leaves or twigs. The dried or fresh branches should not be used for spearing food, for preparing a cooking fire, or as a food skewer. Many of the oleander relatives, such as the desert rose ( Adenium) found in East Africa, have similar leaves and flowers and are equally toxic.
There is an ancient account mentioned by Pliny the Elder in his Natural History, who described a region in Pontus in Turkey where the honey was poisoned from bees having pollinated poisonous flowers, with the honey left as a poisonous trap for an invading army. The flowers have sometimes been mis-translated as oleander, but oleander flowers are nectarless and therefore cannot transmit any toxins via nectar. The actual flower referenced by Pliny was either Azalea or Rhododendron, which is still used in Turkey to produce a mad honey.
Oleander is the official flower of the city of Hiroshima, having been the first to bloom following the atomic bombing of the city in 1945.
==Gallery==
Cultivation
History
Nerium oleander has a history of cultivation going back millennia, especially amongst the great ancient civilizations of the Mediterranean Basin. Some scholars believe it to be the rhodon (rose), also called the 'Rose of Jericho', mentioned in apocryphal writings (Ecclesiasticus XXIV, 13) dating back to between 450 and 180 BC.
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 tree, 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.
Ornamental gardening
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. It is most commonly grown in its natural shrub form, but can be trained into a small tree with a single trunk. Hardy versions like white, red and pink oleander will tolerate occasional light frost down to , though the leaves may be damaged. 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.
Colors and varieties
Oleander flowers are showy, profuse, and often fragrant, which makes them very attractive in many contexts. Over 400 cultivars have been named, with several additional flower colors not found in wild plants having been selected, including yellow, peach and salmon. Many cultivars, like 'Hawaii' or 'Turner's Carnival', are multi-colored, with brilliant striped corollas. The solid whites, reds and a variety of pinks are the most common. Double flowered cultivars like 'Mrs. Isadore Dyer' (deep pink), 'Mathilde Ferrier' (yellow) or 'Mont Blanc' (white) are enjoyed for their large, rose-like blooms and strong fragrance. There is also a variegation form, 'Variegata', featuring leaves striped in yellow and white. Several dwarf cultivars have also been developed, offering a more compact form and size for small spaces. These include 'Little Red', 'Petite White', 'Petite Pink' and 'Petite Salmon', which grow to about at maturity.
Toxicity
Oleander is a poisonous plant because of toxic compounds it contains, especially 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 are toxic when ingested. Side effects after ingestion are weakness, diarrhoea, nausea, vomiting, headache, stomach pain, and death.
Effects of poisoning
Ingestion of this plant can affect the gastrointestinal system, the heart, and the central nervous system. The main effect of cardiotoxic glycosides is positive Inotrope. Glycosides bind to the sarcolemma transmembrane ATPase of cardiac muscle cells and compete with K+ ions, inactivating the enzyme. This results in an accumulation of Na+ and Ca2+ ions into the cardiac muscle cells, leading to stronger and faster heart contractions. Moreover, the increased amount of extracellular K+ ions may lead to lethal hyperkalemia. 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. Cardiotoxic glycosides are also responsible for stimulating the vagus nerve (leading to sinus bradycardia) and the phrenic nerve (leading to hyperventilation), and lethal brady- and tachyarrhythmias, including asystole and ventricular fibrillation. Oleander poisoning can also result in blurred vision, and vision disturbances, including halos appearing around objects. Oleander sap can cause skin irritations, severe eye inflammation and irritation, and allergic reactions characterized by dermatitis.
Treatment
Poisoning and reactions to oleander plants are evident quickly, requiring immediate medical care in suspected or known poisonings of both humans and animals. Induced vomiting and gastric lavage are protective measures to reduce absorption of the toxic compounds. Activated carbon may also be administered to help absorb any remaining toxins. Further medical attention may be required depending on the severity of the poisoning and symptoms. Temporary cardiac pacing will be required in many cases (usually for a few days) until the toxin is excreted.
Research
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.
Culture
Oracle of Delphi
In a research study done by Haralampos V. Harissis, he claims that the laurel the Pythia is commonly depicted with is actually an oleander plant, and the poisonous plant and its subsequent hallucinations are the source of the oracle's mystical power and subsequent prophecies. Many of the symptoms that primary sources such as Plutarch and Democritus report align with results of oleander poisoning. Harissis also provides evidence claiming that the word laurel may have been used to describe an oleander leaf.
Folklore
The toxicity of the plant makes it the center of an urban legend documented on several continents and over more than a century. Often told as a true and local event, typically an entire family, or in other tellings a group of scouts, succumbs after consuming or other food roasted over a campfire using oleander sticks. Some variants tell of this happening to Napoleon's or Alexander the Great's soldiers.
In painting
Oleander was part of subject matter of paintings by famous artists including:
In literature, film and music
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See also
Notes
External links
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