Son La Prov., Moc Chau Distr., Chieng Son comm., about 1 km to NE from Chieng Son Village, around point 20°46’02.0N 104°37’03.1E. Remnants of primary broad-leaved evergreen forest on tops of hills composed with karstic highly eroded yellow-white limestone at elevation 1150-1250 m a.s.l. Shrub to 2 m tall on mossy exposed rocks. Flowers light yellowish. Occasional.