Common Name: Rhododendron
Scientific Name: Rhododendron arboreum
Nepali Name: Lali Gurans ( लालीगुरास )
Size: 6-12m (height) 
Location: Kakani, Nuwakot

Rhododendron is the national flower of Nepal and can be seen blooming from 1600m to 4000m. The bell-shaped flowers are also used in religious ceremonies for medicines. 

Please feel free to comment below if the above species has been misidentified.