Tree of the Week: Ubiquitous oleander seems to thrive on neglect
Oleander -- Nerium oleander
The Spaniards brought the oleander to Florida in 1565. It had been popular in its native Mediterranean, Middle East, Himalayas and China for at least 4,000 years, in both its scented and odorless flower forms.
This beautiful and basic landscape plant in the dogbane family takes little and gives a lot: endless miles of it bloom for months on end along our freeways, decorate our streets as small trees and adorn our gardens. But along came various leafhoppers, sucking insects such as the sharpshooters, which from their mouthparts transmit the tiny Xylella fastidiosa bacteria, which plug up plants’ internal channels. From the 1990s on, they caused great numbers of oleanders, grapes and other plants to become scorched and die in the Southland. Research is going on to find predators that will attack the sharpshooters and create Xylella-resistant plant varieties.
Oleander is easily trained as an evergreen tree, but basal suckers as easily make it revert back to a shrub. Pruned and maintained as a tree, it can reach 20 feet tall by 12 feet wide. It becomes dense with erect branches. The bark is rough and gray. Lance-shaped, dark green, 4-to-12-inch-long leaves are thick and leathery and occur in pairs or threes. Abundant, long-lasting, 2-to-3-inch-wide pink, white, red or yellow, single or double flowers grow in clusters at the end of the branches. Many named varieties are available. Fruit is a long, narrow capsule that splits open to reveal small seeds. The tree is drought- and smog-resistant, takes most any soil but wants full sun. Besides the sharpshooters, it can host scale, yellow oleander aphid and bacterial gall disease.
Warning: All parts of the tree are poisonous. Do not inhale smoke from burning oleanders, and keep the trees and their foliage away from children’s and pet areas. The tree is suitable for container gardens.
-- Pieter Severynen
Photo: An oleander in Los Angeles. Credit: Pieter Severynen