R. vellereum was placed in synonymy under R. aganniphum on page 590, this judgement being based on the remarks by Cowan and Davidian in the Botanical Magazine (n.s., t.147). However, the reduction was premature, and for two reasons. Dr Chamberlain considers that the two species are distinct; and that an earlier name for R. vellereum is R. principis Franch., the type of which was collected in 1890 by Bonvalot and Prince Henri d'Orléans, that 'young but energetic traveller of royal blood and rare attainments' (Bretschneider, Botanical Discoveries, pp. 912-16, where an account of the journey will be found). It came from the area between Lhasa and Batang – a marginal zone where the vegetation typical of western China fades into that of the Tibetan steppes. The type specimen of R. primuliflorum was, incidentally, collected by them in the same area.
R. principis (vellereum) is indeed closely allied to R. aganniphum, but, according to Dr Chamberlain, the latter has relatively broader leaves with an indumentum that sometimes turns brown and tends to split or become patchy, and also its flowers have thicker pedicels. However, whether the two species are distinct has no bearing on the validity of the name R. principis, which has long priority over both.