''Sorbus leyana''. Ley's whitebeam, is a species of small tree which is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to two sites in southern Wales. It is thought to have arisen by hybridisation of two species of ''

Sorbus ''Sorbus'' is a genus of over 100 species of trees and shrubs in the rose family, Rosaceae. Species of ''Sorbus'' (''s.l.'') are commonly known as whitebeam, rowan ( mountain-ash) and service tree. The exact number of species is disputed depe ...

'', one of which was the rowan. Its closest relatives are some of the other hybrid derived ''Sorbus'' species found in Britain.

Description

''Sorbus leyana'' is a shrub or small tree which grows to in the wild, although it will grow taller in cultivation. The best feature distinguishing ''S. leyana'' from its sympatric congeners is by examining the lateral rosette leaves which are normally long and across, meaning that they are 1.2-1.65 times longer than they are wide. These leaves are widest at about the middle and are deeply lobed with the lobes reaching three-quarters of the way to the leaf's midrib and the leaf margin is toothed and normally has 7-10 pairs of leaf veins. The berries are wider than they are long, slightly wider below the middle, with a few small scattered pores and they are blood red in colour when mature.

Distribution and population

''Sorbus leyana'' has been recorded in the wild from just two sites in the Brecon Beacons near Merthyr Tydfil, Darren Fach and Penmoelallt. These two populations are around apart and the total population is around 20 trees.

Habitat and ecology

''Sorbus leyana'' is occurs in scrub or open woodland on crags of Carboniferous

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

at locations where they have access to light. It is apomictic species which normally has a sparse crop of berries from which germination is poor and this results in only a small amount of natural regeneration taking place. On average only 24% of the pollen produced is vailable.

Discovery and origin

''Sorbis leyana'' was discovered by the clergyman and botanist Reverend Augustin Ley in the 19th Century and was named in his honour by Alfred James Wilmott. This species is thought to have arisen from a hybrid between the rowan (''Sorbus aucuparia'') and either the grey whitebeam (''S. rupicola'') or grey whitebeam (''S. porrigentiformis''). It is part of a group of closely related species within the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Sorbus'' which have leaves with deep lobes and small fruits, this group includes English whitebeam (''S. anglica''), least whitebeam (''S. minima'') and the Arran whitebeam (''S. arranensis'').

Conservation

''Sorbus leyana'' is restricted to two sites both of which are protected as a Site of Special Scientific Interest, Darren Fach is within the

Wildlife Trust of South & West Wales The Wildlife Trust of South and West Wales (WTSWW) ( cy, Ymddiriedolaeth Natur De a Gorllewin Cymru) is a Wildlife Trust in south and west Wales, one of 46 such Trusts in the United Kingdom. History Forerunner of the WTSWW, the former West Wal ...

reserve of Darren Fawr. The trees were "rediscovered" in the 1950s by forester Peter Charlesworth and were propagated at the

National Botanic Garden of Wales The National Botanic Garden of Wales ( cy, Gardd Fotaneg Genedlaethol Cymru) is a botanical garden located in Llanarthney in the River Tywi valley, Carmarthenshire, Wales. The garden is both a visitor attraction and a centre for botanical rese ...

. This species is threatened by grazing and shading by taller trees, regeneration appears to be reliant on access to light.

References

External links

* * * {{Taxonbar, from=Q5491011 leyana Endemic flora of Wales Critically endangered plants Taxonomy articles created by Polbot