Nerium oleander aka Oleander

Oleander, Nerium oleander, is an evergreen shrub or small tree in the dogbane family, Apocynaceae. Its wild range runs from the Mediterranean through the Middle East and southern Asia. It reaches India, Myanmar and parts of China. In Europe it grows wild along river banks, gravel beds and dry rocky watercourses. The species name refers to the olive, because the leaves look like olive leaves.

In gardens it usually forms a rounded, multi-stemmed shrub 6 to 12 feet (1.8 to 3.7 m) tall and about as wide. Florida sources report plants of 10 to 18 feet (3 to 5.5 m). Old plants can reach about 20 feet (6 m). Gardeners often train it into a small single-trunked tree, sold as a standard. The stout young twigs are shiny green and later turn light brown. The bark is gray and smooth, becoming shallowly fissured with age.

The leaves are narrow, lanceolate and leathery, about 4 to 8 inches (10 to 20 cm) long. They are dark green above and paler below. They grow in opposite pairs or whorls of three or four. The flowers are funnel-shaped with five petals and a small corona at the throat. They form clusters at the tips of new shoots. Colours include white, pink, red, purple, salmon, apricot and pale yellow. Some forms have double or fragrant flowers. The main bloom runs from late spring to late summer. In frost-free climates it can flower almost all year. Slender paired pods follow, splitting to release tufted seeds that the wind carries.

Oleander needs full sun and well-drained soil. It copes with sand, loam or clay, acid or alkaline. In shade it grows lanky and flowers poorly. It handles drought, heat, wind, poor soil and salt spray. That makes it a good choice for coasts and highway medians. It is not frost-hardy and suits USDA zones 8 or 9 to 11. Brief frosts to about -5 to -8°C may damage the tops. In colder regions, grow it in a container and bring it indoors for winter. It grows fast. Prune in spring and remove basal suckers to keep plants flowering. Butterflies visit the flowers, and deer tend to leave it alone.

Scale, aphids, mealybugs and the oleander caterpillar are the main pests. The caterpillar can strip a plant of leaves within two weeks. Sooty mold, leaf spot and Armillaria sometimes appear. The plant resists Verticillium wilt and Texas root rot. Its branches can break, so early pruning helps build a strong frame.

Every part of oleander is highly poisonous, whether fresh or dried. It contains cardiac glycosides such as oleandrin. Eating even a single leaf has killed children. Symptoms include vomiting, stomach pain, irregular heartbeat and collapse. Dogs, cats, horses, cattle, sheep and goats are all at risk. The sap can irritate skin. Never burn the clippings, because the smoke is toxic. The plant has no known food uses.