Rhododendron

Where it grows

The genus Rhododendron contains over a thousand species, concentrated in the eastern Himalayas, southwestern China, and New Guinea. Nepal’s tree rhododendron forests (R. arboreum) reach twenty metres tall and flame red in spring. R. ponticum was widely planted in Britain as game cover and has become a serious invasive across western Britain and Ireland.

How to recognise it

Evergreen or deciduous shrubs and small trees with leathery, often elliptical leaves and large terminal clusters (trusses) of bell- or funnel-shaped flowers, each with five to seven lobes and ten stamens. The flowers are larger than those of their azalea cousins, frequently four to ten centimetres across, sometimes much larger.

Garden & cultural uses

The Himalayan species captivated nineteenth-century British plant collectors including Joseph Hooker, whose Sikkim expeditions returned with the species that revolutionised European spring gardens. Rhododendron is the national flower of Nepal, where it is called lali gurans, and its young flowers are pickled or made into a tart drink.

In ecology

Eradicating R. ponticum from infested British woodland costs millions of pounds annually; it shades out native ground flora and acidifies the soil, preventing regeneration of oak and ash.