T H E BURREN, COUNTY CLARE, IRELAND

Charles Nelson

Boireann is an Irish word for a rocky place, and there are many places in Ireland with names derived from it. But, The Burren is universally understood as that part of north County Clare domi- nated by hills ofCarboniferous limestone. I t is a region ofparadoxes, bleak yet far from barren, apparently devoid of plants yet luxuriant, populated by species of Arctic and of sub-tropical affinities, a desol- ate place of great beauty.

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Map showing the position (hatched area) of the Burren, Ireland.

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From afar the Burren hills dominate the skyline of north Clare, flat-topped and pale. Closer, the overwhelming impression is of bare, grey rocks, looking like a street pavement, extending for acre upon acre, and criss-crossed by herring-bone walls of the same lichen-splashed limestone. The hills reveal their structure by the tell- tale scailps (the local name for the grykes) and the differential erosion of the strata. Some of the hills, including those overlooking Ballyvaughan, have plain, horizontal layers of limestone, but at Mullagh More, the rocks are sinuously folded and the hills seem to be made of stacked saucers.

The Burren rockscape is not monotonous. The colour changes hour by hour and season by season; it can be intense, almost white- grey on sunny summer afternoons or dark glistening grey after spring showers have washed the land. There are the constantly moving clouds, scudding eastwards and patterning the rock-fields with shadows. Good sunny days are not infrequent, but it does rain on about two days in every three, and on the higher hills the annual precipitation is around 1750 mm. But the water drains away rapidly, disappearing underground through the innumerable fissures in the rocks. Over the millenia, these cracks have widened as the water has dissolved the limestone, and deep beneath the Burren there are networks of underground rivers, streams and caverns. The cave systems include the longest in Ireland reaching for more than 1 1 km. Some of the water returns to the surface in the turloughs, the ephemeral loughs that occupy depressions between the hills. In winter, the inflow ofwater fills the turloughs, but in summer they are drained naturally and in the driest years may be emptied com- pletely. The turloughs are remarkable habitats, providing winter roosts for many water fowl, and presenting the plants that inhabit the depressions with a severe regime of alternating exposure and inundation.

Wind is one of the most critical elements in moulding the Burren landscape and vegetation. Robert Lloyd Praeger described the win- ter weather as a succession of westerly gales with westerly winds in between. These westerlies buffet the land, prune trees and shrubs to ground level, bring rain, and also maintain a relatively mild and equable climate. Frost does occur, but it is not often severe and rarely lasts for long, as the breezes from the ocean are warm. In January and February the mean temperature is about 6"C, while in summer it is only 15°C.

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The Burren’s renown centres on the perplexing composition of its flora, and for the general visitor, on the rich beauty of the plants. The ‘show’ begins in late spring with the cowslips, Primula veris, - whole fields carpeted with them are still seen here, particularly on the stable dunes and the pockets of glacial drift around the edge of the Burren. Primroses, P.vulgaris, also abound, and the false oxslip, P. x tommasinii, the hybrid between the cowslip and primrose, is common. Violets, especially Viola riviniana, and wood anemones, Anemone nemorosa, also bloom at this time and can be found in uncharacteristic habitats, in the open on the limestone pavements. By mid-May the spring gentians, Gentiana verna, are flowering - it is generally reek-

oned that the middle weeks of the month, around 15 May, are the height of the gentian season. The colour of the Burren gentians is pure, rich blue, accentuated by the white corolla throat, but very occasionally colour variants arise - I have seen a plant with the palest of pale blue flowers, and there is one in cultivation, G. uerna ‘Clare’, that has Cambridge blue flowers. As the gentians wane, the mountain avens, Dryas octopetala, are reaching their climax, and whole hillslopes are drifted with the white flowers of this creeping sub-shrub. It is accompanied by early purple orchids, Orchis mascula, mountain everlastings, Antennaria dioica, and the first flowers of the bloody cranesbill, Geranium sanguineum. In a few places, as at Poul- sallagh and Mullagh More, the hoary rockrose, Helianthemum canum,

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is found, and on bright days, their small flowers open fully, carpeting the turf with yellow. Late May and early June also brings into bloom the mossy saxifrages, S. rosacea and S. hypnoides, and the spring sandwort, Minuartia verna.

The Burren ‘specialities’ should not distract visitors from the common plants. The coastal rocks provide habitats for thrift, Armeria maritima, sea campion, Silene vulgaris ssp. maritima, burnet rose, Rosa spinosissima, and bird’s-foot trefoil, Lotus corniculata, among others. Nor should the less spectacular species be over-looked, plants like blue moor-grass, Sesleria albicans, stone bramble, Rubus saxatilis, and madder, Rubia peregrina, which are abundant on the pavements.

Later in the summer the shrubby cinquefoil, Potentilla fruticosa, is in flower, and it provides a colourful ring around some of the turloughs. The other turlough-fringe plant of startling beauty is the turlough violet, Viola persiczfolia, that flowers in late May and has pale sky-blue flowers. I t grows in great drifts near the high-water levels on the turlough edges, below a zone occupied by the dog violet, Viola canina.

The one element lacking in the Burren proper is tall trees. The

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Rubus saxatilis

wind scythes all plants to ground level and the wild goats and domestic animals assist by grazing everything, even yew. In the sheltered nooks and valleys, and where grazing is absent, scrub will develop. Yew, Taxus baccaba, Irish whitebeam, Sorbus hibernica, holly, Ilex aqu$olium, and aspen, Populus tremula, are among the more inter- esting of the Burren woody species. Ash, Fraxinus excelsior, and hazel, Corylus avellana, abound, and hawthorn, Crataegus monogyna, and blackthorn, Prunus spinosa, are also common. In the scailps, such woodland plants as honeysuckle, Lonicera periclymenum, occur, and ivy, Hedera spp. - including H . hibernica, is everywhere - a richer brighter green, seemingly, than anywhere else.

For botanists, especially those intrigued by the intricacies of plant geography, the Burren offers one the greatest challenges in western Europe. The region does not contain any endemic species, but then

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Ireland as a whole has no undisputed endemics - such taxa as Sorbus hibernica, Salix hibernica and Rumex hibernica either are known outside the island or are merely local variants of complex species. Nor does the Burren have a substantial number ofspecies unique to it - all but two or three grow in other parts of Ireland. Dropwort, Filipendula vulgaris, is found in the limestone pavement and grassland west of Gort, but it is not recorded anywhere else in Ireland, although it is relatively frequent in eastern Britain. Arenaria noruegica, found on the high western hills of the Burren in 1961, has eluded botanists since its discovery; if it still exists here it is confined to this one site in Ireland. The hoary rockrose is also found on the Aran Islands, a few kilometres off the west coast; the islands belong to the same geo- logical structure as the Burren and contain many of the Burren plants, and are, in effect, outliers of the Burren.

Arenaria noruegica

Apart from these three plants, a number of species do have their main Irish populations in the area, including mountain avens, spring gentian, bloody cranesbill, shrubby cinquefoil and maid- enhair fern. The absence of competition from shrubby plants and trees, must account, in part, for this.

The Burren’s major paradox is the intermingling of plants with different geographic propensities. Arctic species occupy habitats side by side with sub-tropical species. This is exemplified by the not infrequent sight of the spikes of Irish orchid, Neotinea maculata, among the flowers of mountain avens, and of maidenhair ferns, Adiantum capillus-ueneris, growing in scailps beside a patch of spring gentians. The plants of southern affinity include the Irish orchid, several mossy saxifrages, maidenhair fern and the bloody cranesbill, while those of northern and montane affinity are mountain avens, spring

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gentian, pyramidal bugle, Ajugapyramidalis, shrubby cinquefoil and mountain everlastings. However, these species groups are not clearly delimited and there is a danger of over-simplifying the phy- togeographic problem by such broad groupings. What is perhaps the greater puzzle, is the presence at low altitude in a mild environment of essentially northern plants like mountain avens and pyramidal bugle.

The resolution ofthese conundrums is, I suggest, still far off. None has yet been explained satisfactorily, despite the diligent researches ofmany botanists, and it is more than likely that we will bc able only to arrive at solutions that present the least improbable scenario. That the Burren acts as a refugium for the plants that were wide- spread in colder epochs seems reasonable, for remains of mountain avens have found in post-glacial deposits. But there is no trace of such common Burren plants as spring gentian and shrubby cin- quefoil in the earlier post-glacial deposits. As for the southern plants, they cannot have survived the last glaciation here as the whole area was under an ice-cap. The explanation of their presence presents many more difficulties, and is undoubtedly linked with the remarka-

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ble concentration of species with similar propensities - for example the heathers, Erica ciliaris, E. mackaiana and Daboecia cantabrica - in Connemara, on the northern side of Galway Bay. Did they survive tens of thousands of years in some warm coastal niche on the continental shelf during the glacial period, or did they migrate northwards with remarkable rapidity along the continental shelf from Iberia after the ice retreated and before the ocean levels reached their present heights?

Given the scientific interest provided by the habitats and species of the Burren it is a matter of concern that so little of the area is protected. O n the roads leading into the region, small signs proclaim the unique significance of the Burren and request visitors not to interfere with the plants. But, in the last few years, a programme was initiated, using funds from the E.E.C. to bombard agricultural land with fertilizers using helicopters. This clumsy work could dramati- cally affect some of the best areas within the Burren if it is not very carefully controlled. Some of the individual plant and animal species are protected by law because they are extremely rare within Ireland, but no protection is afforded to the most abundant plants that make up the Burren’s floral kaleidoscope. The region as a whole is not designated as a national park; small parcels of land are owned by the state and by An Taisce (the National Trust of Ireland) but the total area preserved is minute when compared with the extent of the Burren.

The Burren rockscape with its karst features, its unique flora and fauna, and its historic monuments, deserves protection and, above all, careful scientific management. For example, a complete cessa- tion of farming is not required or desirable, for grazing is an integral factor in maintaining the equilibrium of the present. When grazing is restricted, hazel scrub and eventually ash woodland develops in sheltered areas, eliminating many of the important plant and animal species. Thus, the fairly intense grazing helps to maintain the low, herb-rich sward on the pavements, and with the wind, keeps pruned the shrubs and trees that inhabit the scailps.

There is a small historical footnote to the Burren and our knowl- edge and appreciation of its flora. Apart from the strawberry tree, Arbutus unedo, reported from Ireland in 1640, the first printed records of Irish plants included Burren species - mountain avens, spring gentian and the juniper from the ‘mountains betwixt Gort and Galloway’. I t was little more than chance, I think, that led the Rev.

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Richard Heaton to travel to the region sometime between 1633 and 1640.

Two more centuries passed before any substantial notice was taken of the Burren; some botanists did visit the area but as the science of plant geography was in its infancy, no-one paid much attention to the strange mixture of plants. Visiting botanists tended to travel to Connemara and Killarney, with little more than a glance at the Burren from a carriage window. In 1852 the Rev. Thaddeus O’Mahony, noted some of the peculiar botanical features of the Burren, but it was left to a geologist, Frederick Foot, to write the first full paper on the distribution of plants in the region. His article contains much of interest, and even records a local legend about the shrubby cinquefoil’s origin. Since Foot’s time, the people of the Burren have become used to the botanists who, in the words 0fW.M. Letts, are ‘the doubled-up figures that stoop over every cranny, scramble up the hills, or crawl on all fours over the terraces’. They have become part of its fauna, and spend hours and days searching among the scailps for morsels of knowledge.

T H E SAPROPHYTIC GENUS CORSIA I N T H E SOLOMON ISLANDS

Phillip Cribb

The flowering of forest floor saprophytes is rarely predictable and it is usually a matter of luck rather than judgement when they are found in the wild. I was particularly pleased then on a recent visit to the Solomon Islands when on two of the islands, Guadalcanal and Kolombangara, I chanced upon saprophytic plants which I, a t first, mistook for orchids. Scanning the ground while climbing up steep slopes in montane forest, I noticed small saprophytic buff-coloured plants bearing a single terminal reddish-tinged, orchid-like flower with a large erect heart-shaped lip. Closer inspection of the central part of the flower revealed six yellow anthers and a stigma which was obscurely trilobed at the apex, altogether a most unorchid-like arrangement .

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