Sorbus minima
Encyclopedia
Sorbus minima, commonly known as the lesser whitebeam or least whitebeam, is a shrub
belonging to the subgenus
Aria (whitebeam
s) in the genus
Sorbus
. It is endemic to Wales
where it grows at a few sites in Breconshire. It is an apomictic microspecies
which reproduces asexually
and so is reproductively isolated
from its close relatives such as the Swedish whitebeam, S. intermedia
. It probably originated as a hybrid between the rock whitebeam (S. rupicola
) and the rowan (S. aucuparia
). It was first discovered in 1893 by Augustin Ley, the vicar of Sellack in Herefordshire
who travelled widely in Wales.
It is a slender, deciduous
shrub which can reach three metres in height. The leaves
are 6–8 centimetres long and are fairly narrow and oval in shape being 1.8–2.2 times as long as they are broad. They are acutely pointed at the tip and base, have 7–10 (usually 8 or 9) pairs of veins and are lobed one fifth to one third of the way to the midrib. The flower
s are produced in May and June and their petal
s are 4 millimetres long and white. The red berries
are 6–8 millimetres across with a few small lenticel
s.
It grows on carboniferous limestone
cliffs near Crickhowell
in the eastern Brecon Beacons
. The largest population is at Craig y Cilau
National Nature Reserve
where, in September 2002, 730 plants were counted within the reserve with several more in surrounding areas. Smaller numbers grow further west at Cwm Cleisfer and a single plant remains at Craig y Castell. It formerly also occurred at Blaen Onneu.
In 1947 the species was endangered by British Army mortar
practice in and around its habitat. By raising the issue in the Commons, and inducing War Secretary
Frederick Bellenger
to order the Army to pull out of the area, Tudor Watkins
, Labour
MP
for Brecon and Radnorshire
is crediting with preserving the species from extinction.
The species has been affected by quarrying which has destroyed many plants and reduced the amount of available habitat
. It can recolonize disused quarries but does not reach the same population density as at undisturbed sites. All the locations where the species grows, apart from Cwm Cleisfer, now have some kind of protection and a population is kept at the National Botanic Garden of Wales
.
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
belonging to the subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
Aria (whitebeam
Whitebeam
The whitebeams are members of the Rosaceae family, comprising subgenus Aria of genus Sorbus, and hybrids involving species of this subgenus and members of subgenera Sorbus, Torminaria and Chamaemespilus. They are deciduous trees with simple or lobed leaves, arranged alternately...
s) in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Sorbus
Sorbus
Sorbus is a genus of about 100–200 species of trees and shrubs in the subfamily Maloideae of the Rose family Rosaceae. Species of Sorbus are commonly known as whitebeam, rowan, service tree, and mountain ash...
. It is endemic to Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
where it grows at a few sites in Breconshire. It is an apomictic microspecies
Apomixis
In botany, apomixis was defined by Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization. This definition notably does not mention meiosis...
which reproduces asexually
Asexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
and so is reproductively isolated
Reproductive isolation
The mechanisms of reproductive isolation or hybridization barriers are a collection of mechanisms, behaviors and physiological processes that prevent the members of two different species that cross or mate from producing offspring, or which ensure that any offspring that may be produced is not...
from its close relatives such as the Swedish whitebeam, S. intermedia
Sorbus intermedia
Sorbus intermedia is a species of whitebeam in southern Sweden, with scattered occurrences in easternmost Denmark , the far southwest of Finland), the Baltic States, and northern Poland....
. It probably originated as a hybrid between the rock whitebeam (S. rupicola
Sorbus rupicola
Sorbus rupicola, known as Rock Whitebeam, is a rare shrub or small tree best known from the British Isles but also reported from Norway, Sweden and Russia. It prefers basic soil near edges of forests or other shrubs. If growing to full trees, S. rupicola can reach heights of 3—5 m...
) and the rowan (S. aucuparia
Sorbus aucuparia
Sorbus aucuparia , is a species of the genus Sorbus, native to most of Europe except for the far south, and northern Asia...
). It was first discovered in 1893 by Augustin Ley, the vicar of Sellack in Herefordshire
Herefordshire
Herefordshire is a historic and ceremonial county in the West Midlands region of England. For Eurostat purposes it is a NUTS 3 region and is one of three counties that comprise the "Herefordshire, Worcestershire and Gloucestershire" NUTS 2 region. It also forms a unitary district known as the...
who travelled widely in Wales.
It is a slender, deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
shrub which can reach three metres in height. The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are 6–8 centimetres long and are fairly narrow and oval in shape being 1.8–2.2 times as long as they are broad. They are acutely pointed at the tip and base, have 7–10 (usually 8 or 9) pairs of veins and are lobed one fifth to one third of the way to the midrib. The flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s are produced in May and June and their petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals lying...
s are 4 millimetres long and white. The red berries
Berry
The botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors....
are 6–8 millimetres across with a few small lenticel
Lenticel
A lenticel is an airy aggregation of cells within the structural surfaces of the stems, roots, and other parts of vascular plants. It functions as a pore, providing a medium for the direct exchange of gasses between the internal tissues and atmosphere, thereby bypassing the periderm, which would...
s.
It grows on carboniferous limestone
Carboniferous limestone
Carboniferous Limestone is a term used to describe a variety of different types of limestone occurring widely across Great Britain and Ireland which were deposited during the Dinantian epoch of the Carboniferous period. They were formed between 363 and 325 million years ago...
cliffs near Crickhowell
Crickhowell
Crickhowell is a small town in Powys, Mid Wales.-Location:The name Crickhowell is taken from that of the nearby Iron Age hill fort of Crug Hywel above the town, the Welsh language name being anglicised by map-makers and local English-speaking people...
in the eastern Brecon Beacons
Brecon Beacons
The Brecon Beacons is a mountain range in South Wales. In a narrow sense, the name refers to the range of popular peaks south of Brecon, including South Wales' highest mountain, Pen y Fan, and which together form the central section of the Brecon Beacons National Park...
. The largest population is at Craig y Cilau
Craig y Cilau
Craig y Cilau is a limestone escarpment in the Brecon Beacons National Park in Powys, Wales.It was declared a National Nature Reserve in 1959 because of its importance for wildlife, particularly plants...
National Nature Reserve
National Nature Reserve
For details of National nature reserves in the United Kingdom see:*National Nature Reserves in England*National Nature Reserves in Northern Ireland*National Nature Reserves in Scotland*National Nature Reserves in Wales...
where, in September 2002, 730 plants were counted within the reserve with several more in surrounding areas. Smaller numbers grow further west at Cwm Cleisfer and a single plant remains at Craig y Castell. It formerly also occurred at Blaen Onneu.
In 1947 the species was endangered by British Army mortar
Mortar (weapon)
A mortar is an indirect fire weapon that fires explosive projectiles known as bombs at low velocities, short ranges, and high-arcing ballistic trajectories. It is typically muzzle-loading and has a barrel length less than 15 times its caliber....
practice in and around its habitat. By raising the issue in the Commons, and inducing War Secretary
Secretary of State for War
The position of Secretary of State for War, commonly called War Secretary, was a British cabinet-level position, first held by Henry Dundas . In 1801 the post became that of Secretary of State for War and the Colonies. The position was re-instated in 1854...
Frederick Bellenger
Frederick Bellenger
Captain Frederick John Bellenger was a British surveyor, journalist, soldier and Labour Party politician.-Soldier:...
to order the Army to pull out of the area, Tudor Watkins
Tudor Watkins, Baron Watkins
Tudor Elwyn Watkins, Baron Watkins was a Welsh Labour Party politician.- Background :Watkins was born at Abercrave on 9 May 1903...
, Labour
Labour Party (UK)
The Labour Party is a centre-left democratic socialist party in the United Kingdom. It surpassed the Liberal Party in general elections during the early 1920s, forming minority governments under Ramsay MacDonald in 1924 and 1929-1931. The party was in a wartime coalition from 1940 to 1945, after...
MP
Member of Parliament
A Member of Parliament is a representative of the voters to a :parliament. In many countries with bicameral parliaments, the term applies specifically to members of the lower house, as upper houses often have a different title, such as senate, and thus also have different titles for its members,...
for Brecon and Radnorshire
Brecon and Radnorshire (UK Parliament constituency)
Brecon and Radnorshire is a county constituency of the House of Commons of the Parliament of the United Kingdom. Created in 1918, it elects one Member of Parliament by the first past the post system of election; until 1997 its name was simply Brecon and Radnor.The Brecon and Radnorshire Welsh...
is crediting with preserving the species from extinction.
The species has been affected by quarrying which has destroyed many plants and reduced the amount of available habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
. It can recolonize disused quarries but does not reach the same population density as at undisturbed sites. All the locations where the species grows, apart from Cwm Cleisfer, now have some kind of protection and a population is kept at the National Botanic Garden of Wales
National Botanic Garden of Wales
The National Botanic Garden of Wales is situated near Llanarthney in the Towy Valley, Carmarthenshire, Wales. The garden is both a visitor attraction and a centre for botanical research and conservation, and features the world's largest single-span glasshouse measuring long by wide.NBGW seeks...
.
Sources
- Ellis, R. G. (1983) Flowering Plants of Wales. National Museum of Wales, Cardiff.
- Stace, Clive A. (1997) New Flora of the British Isles. Cambridge University Press.
- Tutin, T. G. et al. (1968) Flora EuropaeaFlora EuropaeaThe Flora Europaea is a 5-volume encyclopedia of plants, published between 1964 and 1993 by Cambridge University Press. The aim was to describe all the national Floras of Europe in a single, authoritative publication that helped readers identify any wild or widely cultivated plant in Europe to the...
, Volume 2. Cambridge University Press.