Northwest of the Macgillycuddy’s Reeks, the Dingle peninsula sticks out into the Atlantic like a long, ridged finger built of sandstones and slates with its more geologically complex northwestern tip fringed with dramatic sea cliffs. The highest point there is Mount Brandon (952 m). Falling away from the eastern side of the summit the cliffs drop into a series of lakes, sometimes called paternoster lakes – they are strung out like rosary beads – each one lower than the previous one. Growing near the highest lake, at 715 m, are alternate water-milfoil and quillwort, at their most elevated stations known in Ireland. Praeger, writing in the Botanist in Ireland, reckoned that these cliffs were a repository of interesting species: ‘the richest alpine ground in the country’. Expeditions by Curtis between 1988 and 1990 in search of alpine bistort have brought renewed evidence of their richness.23 The Mount Brandon range, located in one of the remotest areas of Ireland and set in stunning scenery, would certainly repay more intensive investigations by botanists.
The arctic-alpines recorded, apart from the bistort, include alpine lady’s-mantle (found only here, at one other site in south Kerry and near Lough Ouler, Co. Wicklow), alpine meadow-grass (also only here and in the Benbulbin mountain range, Co. Sligo), alpine meadow-rue, alpine saw-wort, dwarf willow, yellow saxifrage, purple saxifrage, starry saxifrage, mountain sorrel and the alpine species, holly fern. The holly fern, like two other ferns present – the parsley fern and green spleenwort – is one of the true mountain ferns, and is usually found growing in crevices of base-rich rocks. The victim of unscrupulous plant collectors in the past, it is restricted to western Ireland where it has been recorded from seven sites, the most easterly being in Co. Fermanagh.16
Caha Mountains, Counties Cork and Kerry
The Caha Mountains, made up of a great ridge of Old Red Sandstone, lie some 40 km southwest of Macgillycuddy’s Reeks. The northern side presides over the majestic Kenmare Bay while to the south they slope down to Ban try Bay. The Cork–Kerry border runs through the high ridge, Hungry Hill being the highest point at 685 m. The interest of Caha rests with a most exciting discovery, made in July 1964, of the small and delicate recurved sandwort found growing in narrow cracks of bare outcrops of Old Red Sandstone slabs east of Knockowen (658 m) and to the north-northeast of Cushnaficulla summit (594 m).24 About 1,000 plants were found at each of the locations. The Caha Mountains are the only known station in Ireland for this sandwort and it has never been recorded in Britain. The plant is a short and small tufted perennial with prostrate to semi-erect woody stems, forming a compact cushion of leaves. It is distinguished from the somewhat similar spring sandwort, also found on mountains (locally in Clare, Antrim, Derry and on the Aran Islands, Co. Galway) by having mostly down-curved leaves and 5–7 veins on the white sepals. Its white flowers, which seem large in relation to the overall plant size, bloom from June to August.
How is it that recurved sandwort only occurs on the Caha Mountains and nowhere else in Ireland or Britain? The nearest recorded station is in the Serra de Gerez in Portugal from where it extends through the Pyrenees and Alps and further eastwards, in suitable siliceous mountain ranges, to the Romanian Carpathians.7 Geological evidence – no signs of glacial smoothing on the stone slabs: their present surface corresponds exactly to the bedding plane of the sandstone and knowledge of known movements of the ice sheets in the area – shows that the summits of both Knockowen and Cushnaficulla were spared the rigours of the ice sheets and overlooked the glaciers moving around below. Clearly the peaks were ice fee and could have acted as refugia for the sandwort during the last and earlier glaciations.25,26 Webb was of the opinion that the recurved sandwort was present in Ireland long before the last glaciation.7
While the recurved sandwort does not fall into the category as one of the 16 arctic-alpine species in Ireland, it is the only true ‘alpine’ species in the country according to the criteria of Webb as laid out earlier in this chapter. The presence of this sandwort on the Caha Mountains strengthens the argument that many species of the Irish flora are not recent immigrants but members of a more ancient flora that was able to survive in glacier-free areas during the Ice Age.
Benbulbin mountain range, Co. Sligo
These mountains are part of a Carboniferous limestone plateau that has survived the gradual down-wearing of the surrounding landscape over millions of years. The whole area, reaching 450–600 m in height, extends over about 500 km2 between Lough Gill in Co. Sligo and Lough Melvin in Co. Leitrim. There is no evidence from glacial deposits or markings by moving ice sheets to suggest that the mountains were covered by ice during the main phase of the Midlandian cold stage to the end of the Drumlin phase of the Midlandian cold stage (79,000–13,000 years ago), so they would have been available as refugia for flora and fauna when the ice sheets tore up and scoured the lower ground, destroying all forms of life.
Evidence that some of the existing Benbulbin mountain flora thrived at lower levels many thousands of years ago comes from plant materials identified from interstadial deposits of mud and moss peat uncovered beneath a drumlin at Derryvree, Co. Fermanagh, and from silt, exposed below glacial till by a river slicing through a drumlin at Hollymount, near Lisnaskea, Co. Fermanagh. They date from before 30,000 and 40,000 years ago respectively. Analysis of the plant materials indicate that the vegetation of the time was characteristic of a cold climate in a tundra landscape. The species identified included the following arctic-alpine and alpine plants: dwarf willow, mountain sorrel, fringed sandwort, purple saxifrage and mountain avens.27 Today the cliffs and screes of Benbulbin and surrounding mountains are one of the most important habitats for these species in Ireland, and include the only known site for the fringed sandwort. It is highly likely that in the face of approaching ice sheets these and other species moved up the mountain to take refuge from the advancing ice glaciers. Whether they survived the long period of polar desert conditions, with intense cold, is less certain.
Benbulbin, Co. Sligo. An uplifted carboniferous limestone plateau with dramatic cliffs, the home of many rare arctic-alpine plants.
Benwiskin (514 m), Co. Sligo, as dramatic as the nearby cliffs of Benbulbin (F. Guinness).
The best known part of the Benbulbin mountain range is the spectacular western spur where the eponymous summit rises to 526 m with its high, sculptured profile. Two large, cliff-walled valleys, each with a lake – Glencar Lough in the south and Glenade Lough in the east – bisect the two mountain lobes and provide topographical diversity to an already very dramatic landscape. The Benbulbin area, extending from Co. Sligo to Co. Leitrim, is so extensive that it would take a botanist at least seven days, working at a feverish pitch, to do the place justice. There are, however, two ‘hot spots’ for the arctic-alpines and alpines.
The first area is the cliffs of Annacoona in the Gleniff Valley, guarded at the northwest entrance by Benwiskin (514 m) which rises to a remarkable pinnacle, like the Matterhorn, surveying the landscape. The Annacoona cliffs face northeast, overlooking the great cirque of Gleniff, gouged out by a glacier. On a still summer’s day the croaking of ravens, rolling around and playing aerobatics along the steep cliffs, the occasional shrieking of a peregrine and the bleating of sheep are the only sounds in this otherwise silent valley. On the cliffs at Annacoona the arctic-alpine flora starts from an altitude of about 244 m upwards. The rarest species is fringed sandwort which has its home here on the upper sections of the limestone cliffs, between 300 and 550 m. This small and deceptively dainty, white-flowered and slightly hairy perennial is a member of the Caryophyllaceae