Vientiane Prov., Kasi Distr., Thong Mout village, around point 19°25′19.7”N 102°08′32.7”E.
Primary broad-leaved evergreen forest on very steep slopes and on cliffs of remnant mountain composed with solid crystalline highly eroded limestone at elevation about 1550 m.
Terrestrial and lithophytic fern on very steep shady rocky slope. Very common.