N. Viet Nam. Ha Giang Province, Quang Ba District, Bat dai Son. Primary forest on limestone with Biota sp., Fraxinus, Quercus, Pseudotsuga, Acer and Taxus dominants along ridge and below peak at elev. 1100-1200 m (about 23°07′N 105°02′E). Lithophytic vine 1-1.5 m. Occasional. DKH 5156 5 April 2000