Described from a cultivated collection originally made above Tram Tau, near the town of Nghia Lo, Vietnam. The description contrasts this species with P. petelotii, differing by having pale bluish purple flowers with notched and dentate corolla. Leaves are dull green to brownish green, crisped, often denticulate and with petioles winged to the base. Unlike P. petelotii there is no evidence that the inflorescence produces plantlets. Recently seen on Mt. Fansipan where P. petelotii also occurs.