Vietnam, Thua Thien – Hue Prov., Nam Dong Distr., Huong Son Municipality, around point 16°10′22′'N, 107°36′24′'E.
Fractionally logged primary closed broad-leaved evergreen lowland forest along La Ma River on very steep hill slopes composed with clayey shale and sandstone at elevation about 300 m a.s.l.
Undershrub 0.5-1 m tall on shady rocky stream slope. Calyx purple. Occasional.