Diapensia
Encyclopedia
Diapensia lapponica is a plant in the family Diapensiaceae
Diapensiaceae
Diapensiaceae is a small family of flowering plants, comprising 12 species in five genera. Three of the genera, Berneuxia, Galax, and Pyxidanthera, contain only a single species. The Asian species of Shortia were formerly separated as the genus Schizocodon, and some authors still recognize S....

, the only circumpolar species in the genus Diapensia, the others being mainly in the Himalayas. It is a circumboreal
Circumboreal Region
The Circumboreal Region is a floristic region within the Holarctic Kingdom in Eurasia and North America, as delineated by such geobotanists as Josias Braun-Blanquet and Armen Takhtajan....

 arctic-alpine
Arctic-alpine
An arctic-alpine taxon is one whose natural distribution includes the Arctic and more southerly mountain ranges, particularly the Alps. The presence of identical or similar taxa in both the tundra of the far north, and high mountain ranges much further south is testament to the similar...

 species which grows on exposed rocky ridges that are kept free from snow by high winds .

It is a small cushion
Cushion plant
A cushion plant is a compact, low growing, mat forming plant that is found in alpine, subalpine, arctic, or subarctic environments around the world...

-forming evergreen
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...

 perennial
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...

 shrub
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...

, up to 15 cm in height. It has oval blunt leathery toothless leaves, up to 1 cm long, which are arranged in dense rosettes. It bears solitary white flowers, on stems up to 3 cm tall.

It could be aged by counting growth-rings, and on this basis, many Canadian plants have been shown to live to over a century old .

Two subspecies are recognised:
  • Diapensia lapponica subsp. lapponica in eastern North America
    North America
    North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

    , Greenland
    Greenland
    Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...

    , Scotland
    Scotland
    Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

    , Scandinavia
    Scandinavia
    Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...

    , and western Arctic
    Arctic
    The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...

     Russia
    Russia
    Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

  • Diapensia lapponica subsp. obovata in eastern Arctic
    Arctic
    The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...

     Russia
    Russia
    Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

    , Korea
    Korea
    Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...

    , Japan
    Japan
    Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

    , Alaska
    Alaska
    Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

     and the Yukon
    Yukon
    Yukon is the westernmost and smallest of Canada's three federal territories. It was named after the Yukon River. The word Yukon means "Great River" in Gwich’in....


Status in Britain

In Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

, Diapensia is found only at a single site, Sgurr an Utha , near Glenfinnan
Glenfinnan
Glenfinnan is a village in Lochaber area of the Highlands of Scotland. It is located at the northern end of Loch Shiel, at the foot of Glenfinnan.- Glenfinnan Monument :...

 in Lochaber
Lochaber
District of Lochaber 1975 to 1996Highland council area shown as one of the council areas of ScotlandLochaber is one of the 16 ward management areas of the Highland Council of Scotland and one of eight former local government districts of the two-tier Highland region...

, the species' most southerly site in Europe. Here, the species occurs on acidic soil among stones on the ridge between the summit of Sgurr an Utha and the adjoining hill called Fraoch-bheinn, at 760 to 780 metres above sea-level. Its total extent at this site is less than 5,000 m². A total of 1,200 clumps or mats have been counted, and monitoring since 1980 has not detected any change in this population.

The discovery of Diapensia took place in July 1951; C. F. Tebbutt, a birdwatcher, found the plant, recognising it as "something different" . Diapensia was one of a trio of Arctic plants discovered in Scotland in the early 1950s. Although no new species to Britain had been discovered in Scotland since Victorian times, in 1950, the Arctic plant Koenigia islandica had been found on the Isle of Skye, and in 1952, Artemisia norvegica
Artemisia norvegica
Artemisia norvegica is a species of flowering plant in the aster family known by the common names alpine sagewort, boreal sagewort, mountain sagewort, Norwegian mugwort, arctic wormwood, and spruce wormwood...

was found on Cul Mor
Cùl Mòr
Cùl Mòr is a shapely, twin summited mountain in the far north west of Scotland whose higher summit is the highest point of Inverpolly. It is almost completely separated from its southern neighbour, Cùl Beag...

 . A photograph of the plant by Robert Moyes Adam taken on 14 June 1952 (soon after the initial discovery) is held by the St Andrews University Library .

It flowers at this site in May or June, the exact time varying from year to year. Some sources state that the species is found at a second site  but recent sources state that this is not the case .

The plant is listed in the 3rd edition of the British vascular plant Red Data Book
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

  as vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...

. It is also protected under Schedule 8 of the Wildlife and Countryside Act 1981
Wildlife and Countryside Act 1981
The Wildlife and Countryside Act 1981 is an Act of Parliament in the United Kingdom and was implemented to comply with the Directive 2009/147/EC on the conservation of wild birds...

.
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