Early flowering Rhododendron in the species collection

R. barbatum grows in the wild in the western Himalayas, in hemlock forests at elevations between around 2400 and 3700 m. A tree-form species, it grows up to 10 m tall, has distinctive peeling, patterned bark and long hairs on the petioles, and produces dense clusters of deep red flowers early in the season.

Rhododendron calophytum reaches up to 10 m tall and can be recognized by its leaves that are long and narrow (30 x 8 cm), light green, and almost hairless on the underside, and the large inflorescences of up to 30 bell-shaped flowers with large stigmas.

Rhododendron calophytum, R. davidii, and R. sutchuenense all grow in mid-elevation forests in central China (Sichuan, N Yunnan and/or W Hubei). Find them growing together in the Arboretum and in flower in March or April and note the differences in flower colours (almost violet in R. davidii), patterning on the petals, and the indument on the underside of the leaf veins.

A low-growing (up to around 50 cm), ground-covering species with short-lived open, light-yellow (not golden!) flowers.  Found on mountaintops and scree slopes at 1,500-2,700 m elevation from Central Siberia as far east as Japan (where our material comes from).

Also considered a variety of Rhododendron mucronulatum, R. dauricum is widely distributed across Mongolia, Northern China and adjacent Russia and Korea. Forming upright shrubs to around 2 m tall, in a mild winter, it is one of our earliest flowering species, its small, open flowers in a range of shades from pink through to white (such as the larger and later flowering ‘Hokkaido’).

Rhododendron hodgsonii is one of several closely related large-leaved species planted at the Arboretum in the 'Big leaf Valley'. From the Himalayas at 2,900-4,300 m elevation, its leaves are up to 40 x 12 cm with a sparse covering of indument on the underside and it produces large inflorescences of red-violet flowers in April.

A low- and dense-growing species known only from one locality in Myanmar, at 3,400 m elevation. The leaves are particularly ridged and shiny on the upper surface with a cinnamon-coloured felty indument underneath; the flowers bell-shaped and white with a rosy tint on the outer side.

A tree-like shrub from the border of China and Burma, Rhododendron lacteum can exceed 5 m in height, with large, round dark green leaves with a heart-shaped base and greyish brown indument underneath. Yellow, broadly bell-shaped flowers are produced in May.

A Chinese species from Yunnan/Sichuan at 2,700-4,400 m elevation. Grows into a bush up to 3 m tall with striking dense covering of orange-brown indument on leaf undersides and shoots. Flowering is in May, when pinkish-red buds open into pinkish-white flowers with darker markings.

The distinction between Rhododendron mucronulatum and R. dauricum in our collections is in the clustered (rather than more evenly distributed) larger flowers of Rh. mucronulatum produced on leafless branches a little later in spring. Varieties of the species are distributed across Japan, Korea and China.

Rhododendron thomsonii from the western Himalayas at 2,400-4,300 m elevation forms a tree up to 7 m in height with round, deep green leaves with a glaucous underside. Pendant, bell-shaped deep red flowers are normally produced in April.