The Arran Whitebeams are tree species unique to the island of Arran, Ayrshire, Scotland. See Also: Whitebeam Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta - liverworts Anthocerotophyta - hornworts Bryophyta - mosses Vascular plants (tracheophytes) †Rhyniophyta - rhyniophytes †Zosterophyllophyta - zosterophylls Lycopodiophyta - clubmosses †Trimerophytophyta - trimerophytes Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongues Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants (also called angiosperms) are a major group of land plants. ... Magnoliopsida is the botanical name for a class: this name is formed by replacing the termination -aceae in the name Magnoliaceae by the termination -opsida (Art 16 of the ICBN). ... Families Barbeyaceae Cannabaceae (hemp family) Dirachmaceae Elaeagnaceae Moraceae (mulberry family) Rosaceae (rose family) Rhamnaceae (buckthorn family) Ulmaceae (elm family) Urticaceae (nettle family) For the Philippine municipality, see Rosales, Pangasinan. ... Subfamilies Rosoideae Spiraeoideae Maloideae Amygdaloideae or Prunoideae The Rosaceae or rose family is a large family of plants, with about 3,000-4,000 species in 100-120 genera. ... Genera Amelanchier - serviceberry, juneberry Aronia - chokeberry Chaenomeles - Japanese quince Cotoneaster - cotoneaster Crataegus - hawthorn Cydonia - quince Eriobotrya - loquat Eriolobus (Malus pro parte) Heteromeles - Toyon Malus - apple, crabapple Mespilus - medlar Osteomeles Photinia Pyracantha - firethorn Pyrus - pear Rhaphiolepis - Indian hawthorn Sorbus - rowan, whitebeam, service tree Stranvaesia - (Photinia pro parte) The Maloideae, or the... Subgenera Sorbus Aria Micromeles Cormus Torminaria Chamaemespilus The genus Sorbus is a genus of about 100-200 species of trees and shrubs in the subfamily Maloideae of the Rose family Rosaceae. ... Species Sorbus subgenus Aria Sorbus aria - Common Whitebeam Sorbus arranensis - Arran Whitebeam Sorbus bristoliensis - Bristol Gorge Whitebeam Sorbus devoniensis - Devon Whitebeam Sorbus folgneri - Folgners Whitebeam Sorbus intermedia - Swedish Whitebeam Sorbus mougeotii - Vosges Whitebeam Sorbus rupicola - Rock Whitebeam Sorbus thibetica - Tibetan Whitebeam Sorbus vestita - Himalayan Whitebeam Plus many other species... In biology, binomial nomenclature is the formal method of naming species. ... In biology, a species is one of the basic units of biodiversity. ... Arran can refer to: arran is the term for a boy with a fat body, a small dick, and a craving to have sexual intercourse with parrots. ... Species Sorbus subgenus Aria Sorbus aria - Common Whitebeam Sorbus arranensis - Arran Whitebeam Sorbus bristoliensis - Bristol Gorge Whitebeam Sorbus devoniensis - Devon Whitebeam Sorbus folgneri - Folgners Whitebeam Sorbus intermedia - Swedish Whitebeam Sorbus mougeotii - Vosges Whitebeam Sorbus rupicola - Rock Whitebeam Sorbus thibetica - Tibetan Whitebeam Sorbus vestita - Himalayan Whitebeam Plus many other species...

Status

These trees, sometimes called the Scottish Whitebeam (Sorbus arranensis) and the Bastard Mountain Ash (Sorbus pseudofennica), are amongst the most endangered tree species in the World if rarity is measured by numbers alone. They are however protected in Glen Diomhan, off Glen Catacol, at the north end of the island by a partly fenced off National Nature Reserve and are monitored by the Rangers Service from Brodick Country Park and particularly by staff from Scottish Natural Heritage. National Nature Reserve is a United Kingdom government conservation designation for a nature reserve of national significance. ... Scottish Natural Heritage (SNH) is a Scottish public body . ...

They are also found in Allt nan Calman, Abhainn Bheag, Allt nan Champ and several other places.

They are typically trees of the mountain slopes, close to the tree line, however they will grow at lower altitudes and they are being grown within the Brodick Country Park and North Ayrshire Council 'Parks and Recreation' staff are growing specimens for conservation purposes. A few specialist garden centres and tree nurseries are able to supply them as grafts and Ardrossan Academy in North Ayrshire has a specimen for its use within the Scottish Higher Biology course (Torrance 2005) in which it features as an example of evolution and survival of the fittest.

History

The oldest preserved specimen is from the Bastard Mountain Ash, S. pseudofennica, collected in 1797 from North Arran and another of the same species is in the British Museum dated 1838, when it was known as Pyrus pinnatifida (the Pear group). S. pseudofennica was authoritatively recognised as a separate species by Clapham, Tutin and Warburg in 1952 (Clapham et al 1958). Landsborough in 1875 noted the two kinds growing in Glen Diomhan and called then French Rowan or Whitebeams. The centre of the museum was redeveloped in 2000 to become the Great Court, with a tessellated glass roof by Foster and Partners surrounding the original Reading Room. ...

The Scottish Mountain Ash, S. arranensis, evoked most collecting interest in 1870 - 1890 and 1920 - 1940, although older herbarium species exist. Mountain Ash is a name used for several unrelated trees. ... In Botany, a herbarium is a collection of preserved plants or plant parts, mainly in a dried form. ...

Evolution

The trees developed in a highly complex fashion, which involved the Common Whitebeam (Sorbus aria) giving rise to the more robust Rock Whitebeam (Sorbus rupicola) which is still found on Holy Isle. This hybrid species is able to survive at higher altitudes and therefore occupies a less competitive niche with fewer tree species able to tolerate the harsher conditions. The Rock Whitebeam interbred with the Rowan / Mountain Ash (Sorbus aucuparia) to produce the hybrid, a fertile separate species the Scottish Whitebeam (Sorbus arranesis) which grows well in this zone of reduced competitive growth at higher altitudes. The Bastard Mountain Ash (Sorbus pseudofennica) arose from a further cross between S. arranensis and the Mountain Ash (S. aucuparia). Species The rowans are plants of the Family Rosaceae, in the Genus Sorbus, Subgenus Sorbus. ...

The Sorbus group are apomictic, producing viable seed without the need for pollination and fertilisation. Each time this hybrid cross occurs a new clone is effectively produced. In botany, apomixis is biological reproduction without fertilization, meiosis or production of gametes, with the result that the seeds are genetically identical to the parent plant. ... As a word, clone was first coined by J.B.S. Haldane as subject for theoretical replication of a frog, though the term clone is derived from κλων, the Greek word for twig. In horticulture, the spelling clon was used until the twentieth century. ...

Smart showed by using physical characteristics that the species were separate and not a result of random variation. Some overlap does however occur and this suggests that some hybridising may occur between the two species.

A number of other Sorbus species have been produced in this way (Keble Martin 1969), such as the Devon Whitebeam, the Bristol Whitebeam, the Cheddar Whitebeam, Irish Whitebeam, Lancaster Whitebeam, etc. (Clapham et al 1958). All are rare and require careful protection and expert habitat management if they are to survive in the wild.

In Scandinavia, particularly Norway, similar species has evolved following similar evolutionary pressures, but quite independently of the Arran Whitebeams.

Islands are well known as sites of endemic species and the Lundy cabbage (Coincya wrightii) is another British example, only growing on Lundy Island off the North Devon coast (Keble Martin 1969). The Lundy Cabbage (Coincya wrightii) is a species of primitive brassica that is endemic to the island of Lundy off the southeastern coast of Great Britain, where ii is sufficiently isolated to have formed ints own speciers, with its endemic insect pollinators. ... The Old Light, Lundy For a map, see the end of this article Lundy is an island in the Bristol Channel of Great Britain, about a third of the way from Devon to the coast of South Wales. ... Categories: Stub | Devon ...

Identifying Characteristics of the Arran Whitebeam Species

The Mountain Ash has a leaf made up of a number of leaflets, whilst the Whitebeam leaf is entire and doesn't even have lobes. The result of crossing the two is that the hybrids begin to merge or mix characteristics, so S. arranensis has lobes but no leaflets and S.pseudofennica, having an extra cross with the 'leafleted' Mountain Ash has a variable number of true leaflets and lobes. These characteritics are not always definitive and sometimes the actual species cannot be ascertined with certainty, possibly due to hybridisation between the species in question (Smart).

Some differences in the flower and seed characteristics is also be noted.

Unlike other endemic British species they do not seem to grow on base-rich soils.

Future Prospects

The actual numbers haven't dropped since the first quantitative survey was carried out in 1897. However this may be a false impression as with more searching more have been found, which does not necessarily suggest a stable population. Various attempts at introducing saplings grown from native seed have had widely differing degrees of success.

Grazing by sheep has probably reduced the population from being widespread and numerous to what it is now, confined to steep slopes, cracks in rock and restricted to the mountainous northern end of the island.

They are not well known to the islanders and two fine specimens were even cut down in the 1980's by a professional gardener working at a site near Brodick Castle. The Ranger's Service have taken steps to increase the distribution of the trees, however a great deal more could be done to make visitors and islanders aware of these unique species possessed by Arran. Brodick Castle is a castle situated outside the port of Brodick on the Isle of Arran, an island in the Firth of Clyde, Scotland. ...

References

• Clapham, A R et al (1958). Flora of the British Isles. Cambridge. Pps.542 - 556.
• Martin, W. Keble (1969). The Concise British Flora in Colour. Ebury Press. p.31.
• Smart, Gillian J.B. A Morphological Study of the Inter-relationships of Sorbus arranensis and Sorbus pseudofennica on the Island of Arran, with their supposed parent species Sorbus rupicola and Sorbus aucuparia. The Todd Centre, Univ Strathclyde, Glasgow.
• Torrance, James (1999). New Higher Biology. ISBN 0-340-74319-0. p.132.