There is a useful article from the Royal Botanic Garden, Edinburgh by Max Coleman (18 December 2014), on the three Sorbus species endemic to the Isle of Arran in the Firth of Clyde, western Scotland:
http://stories.rbge.org.uk/archives/13616
The trees concerned are the Arran whitebeam , Sorbus arranensis, the Arran service-tree, S. pseudofennica and the Catacol whitebeam, S. pseudomeinichii.
Gozde Hasbal, Tugba Yılmaz Ozden and Ayse Can of the Department of Biochemistry, Istanbul University have published (2014) a research article entitled Antioxidant and antiacetylcholinesterase activities of Sorbus torminalis (L.) Crantz (Wild service tree) fruits.
http://www.jfda-online.com/article/S1021-9498(14)00098-2/pdf
The article concluded that fruits of S. torminalis have antioxidant and anti-AChE properties and that the plant might be a natural source of antioxidants and AChE inhibitors. (AChE is an abbreviation of acetylcholinesterase. It is an important enzyme in the nervous system of animals. AChE inhibitors are widely used for the treatment of Alzheimer's disease. Ed.).
This was poem of the week in the Times Literary Supplement on 29th July 2014:
Whitebeam
The sixty-miles-per-hour plants, the growth
that lines the summer corridors of sight
along our major roads, the overlooked
backdrop to Preston 37 miles.
Speed camera foliage; the white flowers
of Mays and Junes, the scarlet fruits of autumn
lay wasted in the getting from A to B.
Hymn to forward-thinking and planting schemes,
though some seem in two minds: the greenwood leaves
are white-furred, have a downy underside
as if the heartwood knew in its heart of hearts
the days among beech and oak would lead to these
single file times, these hard postings
and civilised itself with handkerchiefs.
Paul Farley (2003)
There is an account in BSBI News No. 125 January 2014 pages 37-38 by Ian Bennallick and David Pearman of the discovery of the true service tree (Sorbus domestica) growing wild in Cornwall on a cliff in the upper Camel Estuary.
The species has been known in wild situations in the British Isles since 1993 when it was discovered on cliffs in Glamorgan, south Wales. After this it was also found at sites in the lower Wye and Severn Valleys and the debate continues as to whether it is genuinely wild in the UK or has arisen from ancient introductions.
The Cornish example perhaps strengthens the case for its being a native and some of the older literature does mention Cornish sites for the species, though none are specific enough to be followed up.
The April 2014 edition of the New Journal of Botany (Volume 4 Number 1) contains the following article: British Sorbus (Rosaceae): six new species, two hybrids and a new subgenus by T. C. G. Rich, D. Green, L. Houston, M. Lepší, S. Ludwig and J. Pellicer.
The new species are Evans’s Whitebeam (Sorbus evansii), Green’s Whitebeam (S. greenii), Herefordshire Whitebeam (S. herefordensis), Rich’s Whitebeam (S. richii), Sell’s Whitebeam (S. sellii) and Observatory Whitebeam (S. spectans). These all grow around the Severn and Severn estuary and the article gives maps and details of locations with detailed descriptions of the species should anyone want to go and see them.
The new hybrids are Sorbus aucuparia x S. minima where a single example has been found in the Brecon Beacons and Sorbus porrigentiformis x. S. torminalis with two trees on a cliff in Monmouthshire.
All these species and hybrids have been defined as distinct using genetic analysis techniques.
The new subgenus is Triparens, set up to cover the Swedish Whitebeam (Sorbus intermedia) and S. x liljeforsii, the backcross of S. intermedia with S. aucuparia.
Details of the New Journal of Botany are here: http://www.bsbi.org.uk/NJB_Flyer.pdf
There is a paper in the American Journal of Botany for September 2012 by Durkovic et al. on the significance of leaf traits in the evolution of Sorbi.
It is deeply scientific as this excerpt from the abstract will show "A recently developed atomic force microscopy technique, PeakForce quantitative nanomechanical mapping, was used to characterize the topography of cell wall surfaces of tracheary elements and to map the reduced Young’s modulus of elasticity."
Further details at: http://www.amjbot.org/content/early/2012/08/23/ajb.1100593.abstract
