Phu Tho Prov., Tan Son Distr., Xuan Son Municipality, Du village, around point 21°06′57”N 104°57′17”E. Primary broad-leaved closed wet forest on very steep rocky slopes and cliffs of low remnant mountains composed with highly eroded solid marble-like limestone at elevation 400-600 m a.s.l. Terrestrial herb on steep shady rocky slope. Very common. HAL 12666 16 February 2009 Coll.: L.Averyanov, P.K.Loc, N.T.Vinh, L.T.Son