Vietnam, Thua Thien – Hue Prov., Nam Dong Distr., Huong Son Municipality, around point 16°09′52′'N, 107°36′22′'E (around plot 16°09′36′'N, 107°36′10′'E).
Heavily logged primary closed broad-leaved evergreen lowland forest along La Ma River on very steep hill slopes composed with clayey shale at elevation about 300-450 m a.s.l.
Lithophytic shrub 0.2-0.5 m tall on open wet stream rocks. Flowers deep dirty purple. Locally very common. Co-dominant of stream valley plant communities.