Rhododendron maddenii subsp. maddenii

Rhododendron maddenii Hook. f., Rhododendron Sikkim Himalaya 2: , pl. 18 1851. (Syn: Azalea maddenii (Hook.fil.) Kuntze; Rhododendron brachysiphon Balf. f.; Rhododendron brevitubum I.B.Balf. & Cooper (ambiguous synonym); Rhododendron calophyllum Nutt.; Rhododendron jenkinsii Nutt.; Rhododendron macranthum Griff. (ambiguous synonym); Rhododendron maddenii var. longiflorum W. Watson; Rhododendron polyandrum Hutch.);

S-Tibet, Bhutan, Darjeeling, Sikkim, Myanmar [Burma] (Chin, Kachin), NE-India as per Catalogue of Life;

Rhododendron maddenii
(隐脉杜鹃) is a rhododendron species native to Bhutan, northern India, northeast Myanmar, Sikkim, Thailand, northern Vietnam, and southwestern China, where it grows at altitudes of 2600–3200 meters.  
It is a shrub or small tree that grows to 3–6 m in height, with leathery leaves that are lanceolate, oblong-oblanceolate, or elliptic, 5–15 by 2–8 cm in size. Flowers are predominantly white. 
(From Wikipedia on 20.4.14)

Rhododendron maddenii
Very nice picture, beautifully composed!

Rhododendron closer view : Attachments (1). 4 posts by 3 authors.
A Rhododendron- closer view . From Tang (8-9000 ft). Possibly R. grande
This is Rhododendron maddenii Hook.f. 
Certainly not R. grande --as the flowers in R. grande are not this large (compared to the leaves) and the no. of flowers per inflorescence is 20-30; the adaxial surface of the large leaves show a silvery-white sheen due to the presence of hairy outgrowths.
Also, the flowers do not look similar to R. maddenii (like the flowers of R. maddenii are very large; the style is green not coloured-- one distinct feature is the crown shaped calyx at the base of the floral tube)--- would be nice if we could get a side picture of the flowers.