N. Vietnam, Son La prov., Moc Chau distr., Van Ho municipality, near Hua Tat village (20°46′13′'N, 104°46′12′'E). Primary broad-leaved evergreen closed wet forest along remnant limestone highly eroded ridge at elev. 1100-1300 m a.s.l. Shrub 1.5 m hg. Flowers green-violet, external tepals violet, internal - green. Not common.