Vientiane prov., Vang Vieng distr., Patang village, around point 19°04'15.6''N 102°24'33.2''E. Secondary broad-leaved semi-deciduous dry forest on very steep rocky mountain slopes composed by solid marble like highly eroded limestone at elev. about 670 m a.s.l. Lithophyte on shady cliffs with stem to 30 cm tall. Flower white, inside yellow. Very common.