Rhododendron (mainly Rhododendron ponticum) was introduced by gardeners in the late 18th century into parks and woodlands, where it was also used for game cover and stock shelters.
It spreads by suckers and seeds, which are small and can be carried long distances by wind. It forms dense thickets which shade out native plants, prevent the regeneration of trees and ground vegetation on moors. It is poisonous to livestock and cannot be controlled by grazing.
Rhododendron ponticum is also a host of the fungal disease organisms Phytophthora ramorum and P. kernoviae, which attack oak and beech.
Information and Identification Sheets: Rhododendron