''Sorbus leyana''. Ley's whitebeam, is a species of small tree which is endemic to two sites in southern Wales. It is thought to have arisen by hybridisation of two species of '' Sorbus'', one of which was the

rowan The rowans ( or ) or mountain-ashes are shrubs or trees in the genus ''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, r ...

. 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 In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sh ...

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 The Brecon Beacons ( cy, Bannau Brycheiniog, ) are a mountain range in South Wales. In a narrow sense, the name refers to the range of Old Red Sandstone peaks which lie to the south of Brecon. Sometimes referred to as "the central Beacons" t ...

near

Merthyr Tydfil Merthyr Tydfil (; cy, Merthyr Tudful ) is the main town in Merthyr Tydfil County Borough, Wales, administered by Merthyr Tydfil County Borough Council. It is about north of Cardiff. Often called just Merthyr, it is said to be named after Tydf ...

Darren Fach Darren is a masculine given name of uncertain etymological origins. Some theories state that it originated from an Anglicisation of the Irish first name Darragh or Dáire, meaning "Oak Tree". According to other sources, it is thought to come from ...

and

Penmoelallt Penmoelallt or Onllwyn is a hill in the northern part of the county borough of Rhondda Cynon Taff in south Wales. It lies within the Brecon Beacons National Park and Fforest Fawr Geopark. To its east lies the deep valley of Cwm Taf and to it ...

. 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 The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

limestone at locations where they have access to light. It is

apomictic In botany, apomixis is asexual reproduction without fertilization. Its etymology is Greek for "away from" + "mixing". This definition notably does not mention meiosis. Thus "normal asexual reproduction" of plants, such as propagation from cuttin ...

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 Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

Reverend

Augustin Ley Augustin may refer to: * Augustin (name), male name, variant of Augustine * Augustin (typography), English or 14-point type * Augustin, Brașov, a commune in Brașov County, Romania * Dacian fortress of Augustin, ruined Dacian fortified town in ...

in the 19th Century and was named in his honour by

Alfred James Wilmott Alfred James Wilmott (1888–1950) was primarily an English botanist and museum curator. His author standard form is Wilmott and his area of interest was spermatophytes. His father was an academic who taught at Homerton Training College. 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 ''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 A Site of Special Scientific Interest (SSSI) in Great Britain or an Area of Special Scientific Interest (ASSI) in the Isle of Man and Northern Ireland is a conservation designation denoting a protected area in the United Kingdom and Isle of ...

, Darren Fach is within the Wildlife Trust of South & West Wales reserve of

Darren Fawr Darren is a masculine given name of uncertain etymological origins. Some theories state that it originated from an Anglicisation of the Irish first name Darragh or Dáire, meaning "Oak Tree". According to other sources, it is thought to come from ...

. The trees were "rediscovered" in the 1950s by forester Peter Charlesworth and were propagated at the National Botanic Garden of Wales. 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