This subspecies is quite interesting in that it occurs only in the mountains of S India, far from any other rhododendrons excluding R. arboreum ssp. zeylanicum which occurs on the island of Sri Lanka.  Subspecies nilagiricum is very similar to ssp. zeylanicum in its bullate and convex leaves with a spongy yellow-brown indumentum on the undersides although the leaves of the former are less rounded.  It also shares similar stunning deep crimson to pink flowers but blooms later (late spring to early summer) than ssp. zeylanicum.  Kenneth Cox, who has observed this subspecies in the wild on numerous occasions, places it as an intermediate between ssp. zeylanicum and ssp. delavayi.  Occurs from 6,000 to 7,250 ft. in fairly hot and exposed situations.  Should be an ideal species for areas normally considered too hot and dry  for rhododendron cultivation.

1996sd171  RSBG  (+10?\R1\6).  Quite rare in cultivation, these are grown from seed collected wild by Ken Cox in the Nilagiri Hills of southern India