Upright to rounded deciduous shrubs usually under six feet high. The small obovate and thinly textured leaves are smooth on the upper surface but bristly on the lower. The foliage often turns to shades of yellow in the autumn before dropping. The yellow to greenish-yellow flowers (mid-spring to early summer) are funnel-bell-shaped. This species and its close relatives are unusual in that they are actual deciduous rhododendrons and not “azaleas”. Good in full sun or partial shade. Native over a wide range from the eastern Himalayas to central Yunnan, China. Occurs in a wide variety of habitats from 9,000 to 14,500 ft. 

1974/082  (+5).  Largest flowered yellow member of the Trichocladum series.

1974/111  (viridescens 'Doshong La')  GLE (0).  An award form with light yellow flowers in late May.  AM 1972.

1974/714  (melinanthum)  RBG  (-5).  Form with clear yellow flowers.

1976/205  RBG  (0).  More compact medium growth, lightly glaucous summer foliage and soft tomato red bands along the light yellow flowers.

1977/714 (“var. melinanthum”)  RBGE (0\R1\3). Clear yellow flowers. Very attractive foliage.

1980/002  'Yellow Fellow'  Borde Hill (0).  An Award of Merit form.

1980/159  (chloranthum)  PM  (-5).

1998sd441  CCHH#8170:FSBG  (0\R1\3).  My own collection of this dwarf bushy species which is unusual in that it is deciduous, the leaves turning yellow in the autumn.  The margins of the deep-green rounded leaves have a fringe of long hairs.  Yellow flowers in late spring.  Collected at 11,800 ft. on the Salween/Irrawaddy divide in NW Yunnan, China.  Very attractive plants with a stiff upright habit.

mekongense var. rubrolineatum

Usually deciduous shrubs to 6 ft.  Flowers (April) are creamy yellow and rose-tinged.  Found on forest margins, open pastures and rarely in swamps at 11,000 to 14,000 ft.  India, China.

1966/641  Eckford  (0).  An unassumingly small, partly deciduous plant which awakens in spring with clusters of straw-yellow flowers, rayed pink on the outside.

1976/205  (rubrolineatum)  RBG  (0).  Form with compact medium growth and soft red bands along the light yellow flowers.