Valued worldwide for its ornamental properties, the oleander (Nerium oleander) grows as a distinctive shrub or small tree, with characteristically bright, showy flowers (2)(4)(5). It is a perennial, evergreen species with erect stems and branches, and leathery dark or grey-green leaves (3)(4)(6). The leaves grow in groups of three and are generally long and narrow, with prominent veins running up the centre to the sharply pointed tips (4)(5)(7).
The oleander produces showy, often fragrant, tubular or funnel-shaped flowers which are arranged in clusters at the ends of stems (2)(4)(6). Each flower has five petals, and a base fringed with long petal-like projections (4). The flowers are typically red, pink or white in the wild (2)(4)(6). However, over 400 variants of the oleander have been cultivated to display a huge variety of flower colour, including varying shades of deep to pale creams, pinks, lilacs, purples, yellows, oranges and copper (2)(4).
The fruit is a long, narrow, bean-like capsule which splits along one side to release many seeds. Each individual seed has a plume of reddish-brown hairs, called a pappus, at one end (2)(4)(5)(7).
This species is highly poisonous to humans, domesticated animals and livestock, due to the presence of a group of toxins, called cardiac glycosides, which are found in all parts of the plant (2)(4). Ingestion of any part of the oleander may cause nausea, vomiting, cardiac arrhythmias, low blood pressure and death (2)(4). Even chewing a single leaf has been reported to be lethal in some cases (4). It has been suggested that red flowered varieties of oleander appear to be more toxic than other variants (5).
The oleander is widespread in the Mediterranean region, and is also distributed in parts of northern Africa and southwest Asia, including Iran, the Indian subcontinent and southern China. It is cultivated worldwide as an ornamental plant (2)(4)(7)(8).
In the wild, the oleander occurs along watercourses and in areas of damp, stony ground (4)(7). It is widely cultivated, particularly in warm temperate and subtropical regions, where it grows outdoors in parks, gardens and along road sides (4).
The oleander grows on a wide range of soil types, and is capable of withstanding drought, salt spray and light frosts (2)(8)(9).
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