Houphan Prov., Xon Distr., Nong Hua Pa Noi village, around point 20°13'02.1"N 103°24'23.3"E. Primary and secondary broad-leaved evergreen forest on very steep rocky mountain slopes composed by shaly limestone at elev. 1100-1200 m a.s.l. Epiphyte on tall tree. Flowers white, tepals apices purple-violet. Not rare. LA-VN 1254 11 April 2015.