W. alpina grows on the steep, free-drained, bare faces of calcareous rocks, including pumice tuffs, basalts, mica- and hornblende schists, slates and limestones. Sites are very free-draining, with little competition. From 525 m to 975 m on Ben Lawers (Mid Perth).
First reported from Snowdonia in 1790, current populations of W. alpina are probably relics from more widespread populations in post-glacial times. It suffered a serious decline through collecting in the 19th century. New sites have been discovered since the 1962 Atlas, and current populations appear to be relatively stable.
Circumpolar Boreo-arctic Montane element.
Count of 10km squares in Great Britain: 22
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: 0.11
RDB Species Accounts
Woodsia alpina (Bolton) Gray (Woodsiaceae)
Alpine woodsia, Raineach Mhion Ailpeach, Coredynen Alpaidd
Status in Britain: LOWER RISK - Near Threatened. WCA Schedule 8.
Status in Europe: Not threatened.
W. alpina occupies an extremely specialised habitat, namely, the steep, bare faces of strongly calcareous rocks, within the montane zone, at an altitude of 525-915 metres. It grows on Ordovician pumice tuffs in Snowdonia, Dalradian mica-schists and limestones in Perthshire and Angus, hornblende schist in Angus, and Moine schist in West Inverness. W. alpina is always on treeless crags in Britain, and grows where competition is minimal, rooting in small crevices and niches of knobbly and uneven rock surfaces with only the slightest accumulation of soil. Aspect varies widely, though plants on south-facing rocks can become quite desiccated in dry summers. The immediate associates are most often rupestral lichens and mosses, but vascular plants usually in fairly close company are Asplenium viride, A. trichomanes, Campanula rotundifolia, Cerastium alpinum, Galium boreale, Poa alpina, Saxifraga nivalis, S. oppositifolia, Sedum rosea and Silene acaulis. In number and size of colonies, this is the less rare of our two Woodsia species.
Under exceptional conditions, fronds reach a length of up to 15 cm (Page 1982). Where undisturbed, W. alpina appears to maintain its populations by vegetative renewal of long-established plants, the creeping rhizomes sending up new crowns along their length. Monitoring between 1977 and 1994 has shown that many populations have been remarkably stable. However, some can be dynamic, as shown by one population in which the number of clumps increased from eight to ten between these years, but only three were common to both 1977 and 1994 (Fleming 1995).
W. alpina was first reported by Knowlton from Snowdonia in 1790 (Hyde, et al. 1978). It is geographically more restricted than W. ilvensis in Britain, and found only in Caernarvonshire, Argyll, Perthshire, Angus and West Inverness. The hills between Glen Turret, Perthshire and Glen Fyne, Argyll, and especially the Breadalbane range, are the headquarters of this fern, which is known from at least fourteen different hills here. Even in its Breadalbane stronghold it is unaccountably scarce, and absent from many suitable-looking cliffs - a true relict, from a much colder age. Eastern outliers are in Caenlochan and Glen Doll, and the northernmost locality is on a hill above the Great Glen. W. alpina is still on at least two cliffs in Snowdonia, and was formerly reported from two others. In all, there are thus at least nineteen separate populations. Some are difficult to count accurately, since they are partly or wholly inaccessible, and a few are spread over lofty precipices where even viewing through binoculars is difficult. Colonies range from a few tufts to several hundreds. The hybrid between W. alpina and W. ilvensis has not been satisfactorily confirmed from Britain, despite one or two old reports (Rickard 1972).
This species was seriously depleted in its main Snowdon locality by Victorian fern collectors, and there are large numbers of specimens from Scotland in herbaria. Even during the last 35 years, it has declined in accessible places on the Ben Lawers range and Caenlochan. Most of its sites are NNRs or SSSIs. Few of its cliffs are climbed upon, so that 'gardening' by rock climbers is hardly a problem.
W. alpina is widespread in Alpine and Boreal-Arctic regions of both Old and New Worlds, and appears there to be a plant of calcareous rocks also. In Scandinavia, some populations are on rocks within the Boreal forest zone, and its habitats include large, lichen-crowned blocks in rather open pinewood.
J. Mitchell and D. A. Ratcliffe
PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.
Atlas text references
1986. Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Jalas & Suominen (1972)
1978. Ferns and their allies. The Island of Mull: a survey of its flora and environment. :12.1-12.7.
1965. Vergleichende Chorologie der zentraleuropäischen Flora. Volume 1. 2 vols.
1997. The ferns of Britain and Ireland, edn 2.
1999. British Red Data Books. 1. Vascular plants, edn 3.