Vientiane prov., Kasi distr., Si Sang Vone village, around point 19°06'10.9''N 102°10'46.1''E. Secondary and primary evergreen dry forest on very steep rocky mountain slopes composed by solid marble like highly eroded limestone at elev. 600-750 m a.s.l. Undershrub 1.5-2 m tall in rather open place on rocky steep slope. Flowers light violet. Common.