One fascinating group of species in the British and Irish flora are those with an Arctic–Alpine distribution – species that grow both at high altitudes and at high latitudes, but not in the warmer habitats in between. For the British and Irish examples, this typically means they grow in in the Alps, Pyrenees and/or Carpathians as well as in the Arctic of Scandinavia, but not in the lowlands of the North European Plain. Many of them are restricted to the highest ground our islands contain, although they can also be found down to sea level in some cases.
Some groups are particularly rich in Arctic–Alpine species: willows, saxifrages, sedges and the sandwort subfamily (Caryophyllaceae subfam. Alsinoideae) are all over-represented relative to the lowland flora. Most of the species are perennial, but the woody species that are included are mostly dwarf shrubs rather than tall trees.
I have also included in the list below the few additional species found here and in either the Arctic or the southern European mountains. Because of our latitude and the fact that the mountainous areas are mostly towards the north, our Arctic–Alpine species are closer to their Arctic range than their Alpine one. Accordingly, there are more British–Arctic (but not Alpine) species than British–Alpine (but not Arctic) species. There is also some overlap with the ‘Lusitanian flora’ – those plants that occur in south-western Ireland and in Spain and Portugal but not in the lower-lying ground of western France in between – and species such as the large-flowered butterwort (Pinguicula grandiflora) can reasonably be considered both as an Alpine species that occurs at lower altitudes in the higher latitudes of south-western Ireland, and as a Lusitanian element, growing in the similarly mild, strongly Atlantic climates of Iberia and Munster.
Saxifraga oppositifolia is a classic Arctic–Alpine species in the British and Irish flora, found from Shetland to the Brecon Beacons and from Inishowen to Connemara.
Cornus suecica is found throughout the Arctic, and reaches as far south as the North York Moors and Turton Moor, near Darwen, Lancashire.
Cherleria sedoides is found in the Alps and Pyrenees (and isolated spots in the Balkans and Carpathians) and occurs in Scotland north to Ben Hope, but is not found in the Arctic.