Cerastium arcticum

Tracheophyta MagnoliopsidaCaryophyllaceaeCerastiumCerastium arcticum

Ecology

A montane, tufted perennial herb of acidic and hard basic rocks. It normally occurs in wet, thinly-vegetated crevices and on ledges in N.-facing corries, but has been recorded on a montane fell-field on Skye. Plants may sometimes be found rooted at the foot of mountain cliffs. It is rarely found below 700 m and reaches 1200 m on Ben Nevis (Westerness).

Status

Native

World Distribution

European Arctic-montane element, but absent from mountains of C. Europe; also in N. America.

Broad Habitats

Light (Ellenberg): 7

Moisture (Ellenberg): 6

Reaction (Ellenberg): 4

Nitrogen (Ellenberg): 2

Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 0.8

July Mean Temperature (Celsius): 11.3

Annual Precipitation (mm): 2178

Height (cm): 12

Perennation - primary

Perennial

Life Form - primary

Chamaephyte

Woodiness

Herbaceous

Clonality - primary

Rhizome shortly creeping

Count of 10km squares in Great Britain: 46

Count of 10km squares in Ireland: 0

Count of 10km squares in the Channel Isles: 0

Atlas Change Index: -0.37

JNCC Designations

NBNSYS0000003020

Scarce Atlas Account

Scarce Atlas Account: 

Cerastium arcticum Lange

Arctic mouse-ear

Status: scarce

 

 

Rather scarcer than the closely related C. alpinum, C. arcticum is a montane plant of north-facing corrie walls and mountain cliffs. It is generally found on acid mountains but also occurs on the harder basic igneous rocks such as the gabbro and basalt on Skye and on calcareous Moine schists in Ross. In its corrie habitat it grows on narrow ledges and in crevices but can also become established on block scree and wet montane grassland below mountain cliffs. Characteristic associates are Alchemilla alpina, Arabis petraea, Cochlearia officinalis, Luzula spicata, Poa alpina, Saxifraga hypnoides, the rare S. rivularis, S. stellaris and Sedum rosea. The Trotternish ridge is one of the very few (or possibly the only place) in Britain where the plant occurs on very gently sloping ground. Here it accompanies Koenigia islandica, forming a plant assemblage that is characteristic of the Faeroese fellfields where C. arcticum and Koenigia islandica are widespread. C. arcticum rarely occurs below 600 metres, and is only likely to do so when washed down from higher rocks. It is usually found above 800 metres, reaching its highest altitude at 1190 metres on Beinn Dearg. 

A perennial herb which spreads by long, slender stolons. It also reproduces by seed.

The distribution of C. arcticum appears to be stable, and its habitats are mostly secure from human interference.

Outside Britain, C. arcticum occurs in Iceland, the Faeroe Islands, Fennoscandia, Greenland, Spitzbergen, Russia and arctic America. For a map of its distribution in Europe, see Jalas & Suominen (1983).

Two varieties of this species have been recorded in Britain. C. arcticum var. alpinopilosum is the commoner and is thought to possess genes of C. alpinum var. arcticum has also been recorded from three British localities. A further variant recorded from the eastern Cairngorms approaches var. arcticum but differs markedly in hair structure and is probably a new taxon. The Shetland endemic C. nigrescens is very closely related to C. arcticum and is thought to be conspecific by some botanists (Brummitt et al. 1987). This plant occurs at a much lower altitude. It is treated as C. arcticum subsp. edmondstonii in the Red Data Book (Perring & Farrell 1983). Other varieties of C. arcticum recognised by Hulten extend to Jan Mayen, Novaya Zemlya and Franz Josef Land but have not been recorded in Britain. Hulten explains these varieties in terms of introgressive hybridisation between C. arcticum and C. alpinum (Hulten 1956).

 

 

P. S. Lusby

Atlas text references

Atlas (68a)
Hultén E, Fries M
1986.  Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Jalas & Suominen (1983)
Stewart A, Pearman DA, Preston CD
1994.  Scarce plants in Britain.