This species was sunk in R. spiciferum by Mr Davidian in his revision of the former Scabrifolium series, on the grounds that it ‘is identical with R. spiciferum in every respect’ (Rhod. Cam. Year Book, No. 18 (1964), p. 128). However, Dr Cullen takes a quite different view, maintaining R. pubescens as a distinct species and placing R. spiciferum under R. scabrifolium as a variety (Rev. 1, pp. 82, 84, 85). The differences given by him are that the bristle-like hairs on the upper surface of the leaves are rather lax in R. pubescens, without swollen bases, against stiffer and with swollen bases in R. scabrifolium and its varieties, which also differ from R. pubescens in having a glabrous corolla-tube. But there is little difference in the size and shape of the foliage and the corollas.
The description of R. spiciferum on pages 775-6 serves for R. pubescens, being in fact based on a cultivated plant introduced as R. pubescens and figured under that name in the Botanical Magazine, t.9319. But the geographical distribution is narrower than stated there, R. pubescens, as understood by Dr Cullen, being confined to a small area on the borders between south-west Szechwan and Yunnan. It was found by Forrest near Mu-li and introduced by Kingdon Ward from the same area in 1921 (KW 3952A). Probably most of the cultivated plants (and the one portrayed in the Botanical Magazine) are from this collection. The clone ‘Fine Bristles’ mentioned in the last paragraph also received its award as R. pubescens.
For R. spiciferum as understood by Dr Cullen, see under R. scabrifolium in this supplement.