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 dry broadleaved evergreen forest on very steep rocky slopes of remnant karst limestone ridge at elev. about 300 m a.s.l. Terrestrial fern in shady place. Very common. Codominanthe of forb forest stratum.