N.Vietnam, Bac Kan Prov., Cho Don Distr., Ban Thi Municipality, Cho Dien village, Then Su mt., 22°14′28′'N 105°29′50′'E.
Heavily logged primary closed evergreen wet broadleaved forest on very steep slopes and cliffs of remnant mountains composed with highly eroded crystalline limestone near top of ridge at elev. 250-350 m a.s.l.
Lithophyte on open mossy rocks. Flower buds green. Very common.
HLF 845 26 Dec. 2002.
Coll. Phan Ke Loc, L.Averyanov, Nguyen Anh Duc, To Van Thao, Mai Van Xinh, Nguyen Tien Vinh. Grant from Henry Luce Foundation.