Kindly sponsored by
Peter Norris, enabling the use of The Rhododendron Handbook 1998
New article for Trees and Shrubs Online.
'Rhododendron sumatranum' from the website Trees and Shrubs Online (treesandshrubsonline.
Shrub to 3 m, terrestrial or occasionally epiphytic; young stems covered with substellate scales but quickly glabrescent. Leaves 2.5-8.5 x 1.5-4 cm, mostly elliptic or obovate-elliptic, the apex obtuse to rounded, margin flat or slightly recurved, the base broadly tapering; upper surface at first finely brown-scaly, quickly glabrescent, midrib impressed, laterals 4-7 pairs more or less smooth; lower surface with the midrib raised for most of its length, the laterals flat, moderately densely covered in small brown mostly circular scales which are slightly impressed in shallow pits. Flowers 1-6 per umbel, horizontal to half-hanging; calyx a densely scaly and sparsely hairy disc; corolla red or reddish orange, narrowly funnel-shaped, 2-3 x 1.5-2 cm, sparsely scaly and hairy outside; stamens 10, evenly distributed around the mouth; ovary densely scaly, style glabrous. Royal Horticultural Society (1997)
Distribution Indonesia Northern Sumatra
Habitat 1,800-2,700 m
RHS Hardiness Rating H2
Conservation status Least concern (LC)
This species hybridizes in the wild with R. rarilepidotum and R. retusum to give larger and smaller flowered forms respectively Royal Horticultural Society (1997)