Phu Tho Prov., Tan Son Distr., Xuan Son Municipality, Du village, around point 21°02′55”N 104°56′51”E.
Primary broad-leaved forest on very steep rocky slopes and cliffs of Svoi Lap remnant mountain composed with highly eroded solid marble-like limestone at elevation 600-700 m a.s.l.
Small epiphytic and lithophytic herb on very steep rocky slope and cliffs near to the top of ridge. Flowers light green. Not rare.
HAL 12707 17 February 2009 Photo. Coll.: L.Averyanov, P.K.Loc, N.T.Vinh, L.T.Son.