Wednesday, 6 January 2010

Gough's rock whitebeam (Sorbus rupicoloides)

Gough's rock whitebeam (Sorbus rupicoloides Houston & Rich) a small tree growing to 7 metres of more, was first found and collected by Libby Houston in 2006 in Cheddar Gorge in Somerset, UK.  It has been established by DNA analysis that it is different from the very varied Sorbus aria and other whitebeams that grow in the Gorge.  It is an apomictic microspecies.

Both the leaves and the red fruit are of characteristic colour and shape, but nevertheless resemble other whitebeam species, several of which grow in the Gorge.  Nearest in leaf shape is the rock whitebeam (Sorbus rupicola), hence the specific name of the new species  (Houston et al, 2009).

The tree, so far known from only 12 examples, grows on carboniferous limestone around Gough's Cave on the south side of the gorge near the west end.  With such a small population it qualifies for 'Critically Endangered' status as recommended by the IUCN and it is currently suffering from grazing by the goats that have been introduced to help with the conservation of some of the smaller plants that grow in the gorge.

Now it has been recognised as a microspecies in its own right, Gough's rock whitebeam is likely to get much closer attention so that its long-term future can be secured.


Houston, L., Robertson, A., Jones, K., Rich, T. C. G., Smith, S. C. C., & Hiscock, S. J. (2009) An account of the Whitebeams (Sorbus L., Rosaceae) of Cheddar Gorge, England, with description of three new species.  Watsonia 27: 283-300.

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