Rhododendron griersonianum Balf. f. & Forrest, Notes Roy. Bot. Gard. Edinburgh 11(52–53): 69–71 1919. 



Rhododendron griersonianum Balf.f & Forr. 
Shrub or small tree up to 3 m tallwith bristly and glandular young branches; leaves up to 20 cm long, lanceolate, rusty-woolly beneath, petiole bristly-glandular; flowers scarlet with funnel-like corolla with darker spots, up to 6 cm across, with woolly hairs outside; ovary hairy. 
A chinese plant, Photographed from University of California Botanical Garden.

Nice color, and beautiful capture!