Fuchsia (Photo: C. Krieger)

Before the last glaciation, the Burren enjoyed a warmer climate and tundra conditions obtained which supported the southern (Lusitanian) plant life. Then the ice sheet started to invade the area from the north-east, fingers of ice slowly moving forward and gradually melting, dropping debris and extending the zone of the northern (Hibernian) flora. The ice retreated from this warmer climate bequeathing the unique legacy of northern and southern plants growing side by side.

The mystique of the Burren flora lies in the co-existence of different ecological species growing side by side. There is also the harmonious cohabitation of plants at sea level which, at these latitudes, would normally grow on high mountain tops. There is nowhere else in Europe where Mediterranean and arctic-alpine plants grow together in a similar way.

The reasons why these plants continue to thrive on this limestone plateau can be summarised as follows:

High light density: The lifestyle of the arctic-alpine plants is greatly dependent on the amount of light that they receive. In the Burren a very high degree of light is achieved by reflections from the sea and from the limestone. This light is not depleted by any air pollution, shrubbery or grasses.

Influence of the Gulf Stream: This has the effect of providing the west coast with a warm, moist 'soft' air stream which is the essential element for the survival of the southern species. The winter/summer differential is small.

Natural heat of the limestone: The limestone hills and terraces absorb heat from the sea and summer sunshine and release this heat gradually during the winter. As a result it is warmer on the hills and high valleys in winter than on the low-lying lands.

Generally speaking some plants are more dominant and obvious than others even by their sheer numbers and growth pattern. It would be difficult to miss, or not to be impressed by the sheets and sheets of Mountain Avens (Dryas octopetala) that cover the terraced hills and act as a perfect backdrop for the rich blue Spring Gentian (Gentiana verna). One cannot escape from the gleaming yellow of the Hoary Rockrose (Helianthemum canum) interspersed here and there by the very small, dark blue, sometimes pink Milkwort (Polagala vulgaris). Even though we think of the orchids as being among the later species, the Early Purple Orchid (Orchis mascula) is among the earliest plants, as is the Burren Orchid (Neotinea maculata).

It is important to point out at this stage that should a visit not coincide with the main flowering period of the plants, there is still a chance of seeing a late straggler on a northern-facing slope and equally an early bloom on a southern aspect, the higher one goes the better, and one will very rarely be disappointed even if a visit occurs as early as March or as late as August. A look at the map will help here. July and August have their own rewards and it is difficult to put into words the colour of the Burren in high summer. This is orchid time, a family which has already been described. Now the snow-like dryas have given way to the yellow of Ladies Bedstraw (Galium vernum) punctuated here and there by tussocks of Wild Thyme (Thymus druceii). These two plants are everywhere, on the hillsides, on the rocks, on the walls, in every corner and crevice, even tumbling down to the road. The Wild Thyme could be described as the most hospitable host in the area, because it is to that plant that most of the parasites are attracted, to name a few: Lesser Dodder (Cuscuta epithymum), Eyebright (Euphrasia salisburgensis) and Broomrape (Orabanche rubra). These parasites plug themselves into the thyme and draw from it their own requirements, be it minerals or salts. Neither party seems to suffer from the intrusion.

Like the rest of us, some plant families and groups have more members than others. In the Burren, the geraniums and eyebrights would appear to be particularly well endowed, having seven or eight of each family well represented. Most of the geraniums are quite common in the fields and hedgerows, both on and off the limestone, but one cannot help noticing the prolific growth of the Bloody Cranesbill (Geranium sanguineum). This flower which usually grows in clumps is magenta coloured, so presumably it derives its English name from the fruit it bears, which is a reddish long beak, and the fact that the deeply divided leaves can turn red as they die. For those who wish to make a deeper study of plant life, there is ample scope for doing so in this area, from the very simple families to the very complicated such as the Eyebrights (Euphrasia). These small erect wiry-stemmed flowers with white or violet petals and usually a yellow eye grow abundantly here and can be divided with difficulty into eight identifiable species.

There are in addition some plants which are intermediate between the two species.

Bloody Cranesbill

The isolation of Ireland has resulted in a reduced flora, but there are still about 1,000 species of flowering plants and ferns. As already suggested some of the flowers will be seen almost without looking, others are small, minute and more habitat conscious.