N. Vietnam, Thai Nguyen prov., Vo Nhai distr., Than Sa municipality, vicinities of Kim Son village (N 21°48′ E 105°54′), 23.3 km to 18° of Thai Nguyen city. Primary closed evergreen broadleaved forest on steep rocky slopes and cliffs of remnant karst limestone ridge at about 100 m a.s.l. Terrestrial forb up to 2 m hg in open place. Flowers light pale yellow. Not rare.