Tuyen Quang Prov., Na Hang Distr., Sinh Long Municipality, from central of Nam Duong Vill. to Na Khao Mts. in west direction, around point 22°34′27″ N, 105°22′07″ E, 550 m In heavily logged closed primary evergreen broad-leaved lowland forests on limestone mts. In rich in humus holes; flowers white