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THE BOTANIST IN IRELAND (3)

by Robert Lloyd Praeger D.Sc.


Introduction and Preface; 1-26: Geography, Topology, Climate; 27-47: General history of the flora ;
48-69: Vegetational sub-divisions; 70-78: Human Influence and Botanical workers;
79-219: Some Interesting Plants;

VEGETATIONAL SUBDIVISIONS.

Woodland

48. The Pinus forests that long dominated the Irish landscape gave way to Quercus, and the Quercus woods under human influence have been replaced largely by grassland, and now are seen only where the ground is unsuitable for pasture. But in certain areas – for instance in Kerry at Killarney and Loo Bridge, in Mayo about Pontoon, in Sligo on Lough Gill, in Wicklow in the Vale of Clara – the aboriginal Oak woods still occupy considerable areas, and may be studied to advantage. The native trees which mix as equals with Quercus (usually sessiliflora), which is often completely dominant, are Betula (frequently) and less often Fraxinus*. A number of smaller trees often form a lower stratum in the Quercetum – Ilex, Corylus, Sorbus aucuparia; and more rarely Crataegus, Populus tremula, Taxus, and about Killarney Arbutus (Plate 13); where the Quercus is dwarfed, these may equal it in stature and form a mixed wood.

*Ulmus montana, the only other large indigenous tree, can seldom be claimed as native except on cliffs and rough ground, mostly limestone.
In damp places Alnus and Salices abound. On the western limestone “crags” dense Corylus scrub is often strongly developed, as along the eastern base of the Burren hills in Clare; it may be accompanied by Euonymus, Cornus, and the two species of Rhamnus (348, 350). In addition to Quercus, Betula pubescens alone ever forms pure woods, as at Correl Glen in Fermanagh (438) and near Pontoon in Mayo (374), Mixed woods usually include a good deal of planted trees, particularly Pinus sylvestris and Fagus sylvatica. The native woods of the hills are being replaced largely by Pinus, Picea, and Larix under the aegis of the Forestry Department. Some of the exotic trees, particularly Pinus, Fagus, and Acer Pseudoplatanus, seed freely and tend to extend their boundaries. The ground-flora varies, that of acid soils being the more pronounced, often with a great abundance of Scilla nonscripta, Vaccinium Myrtillus, Luzula sylvatica, Melampyrum pratense, and a profusion of ferns. The saprophytic and parasitic flora of old forests is poorly represented in Ireland. Many even of the English members of these groups are missing, and Neottia, Monotropa, and Lathrcec are here in sole posswsion. Among the few other essentially old forest species of Ireland are Cephalanthera ensifolia, Milium effusum, Festuca sylvatica, Pyrola media, P. minor.

Descriptions of different types of native woodland will be found below, as in 266, 312, 313, 320-2, 348-9, 362, 372, 374, 420, etc.

48 a. The history of Irish forests has not yet been fully worked out. For the earlier (Postglacial) periods, Erdtman has supplied some information by means of pollen analysis. While this method is invaluable for historical purposes, in tracing the changes of vegetation in successive strata, its results, when applied geographically, have to be interpreted in a broad sense, since pollen may be and is carried for long distances by wind. For instance, Tilia pollen has been obtained in Ireland, though it is very doubtful if any species of Lime was ever a native of Ireland. Augustine Henry has made useful contributions to the subject as regards medieval times (Louth Archteol. Journ., 3, 237-245). A good discussion of Irish woods in relation to early human influence will be found in the paper by A. C. Forbes already quoted (28). For the study of the more recent developments in this matter, and especially the question of the, introduction of exotic trees of various kinds into Ireland, the best material is another paper by A. C. Forbes*. He finds that the Church was probably the earliest planter of trees in Ireland, as far back as the 15th century, Taxus being the tree mostly used. The laying down of plantations did not take place on an appreciable scale, he demonstrates, until the 18th century, and then chiefly in conjunction with the creation and improvement of demesnes. The present tendency in tree planting is that of using Western American conifers in place of European species. This, he states, will undoubtedly alter the appearance of the country during the present century.

A. C. FORBES: “Tree Planting in Ireland during Four Centuries.” Proc. Roy. Irish Acad. 41 C 168-199. 1933.
While State planting is not proceeding nearly so quickly as was envisaged by the Irish Forestry Committee of 1908, and while owing to the breaking up of estates under the Land Commission and unsatisfactory general financial conditions private planting has steadily declined, nevertheless in many parts of the country dense areas of conifers are replacing natural Quercus and Betula woods, and tracts of rough pasture and heath, all to the detriment of the indigenous flora.

49. The tree-limit is extremely variable, on account or the accentuated effect of aspect caused by the prevalence of strong westerly winds. Along the exposed W coast it is at sea-level, but shelter at once raises it to from 600 to 800 ft. even in Kerry, as about the Upper Lake of Killarney. On sheltered slopes in the E it may lie at about 1200 It. or more, but the natural Baumgrenze is seldom seen on account of cutting, planting, enclosing, and grazing. As mentioned above (28), it has shifted both eastward (in the west of Ireland) and downward since the climatic optimum of Neolithic times, and may be descending still. In the extreme west, intensive grazing has combined with deterioration of climate to reduce arboreal vegetation to the condition of rare stunted bushes; and in some districts it is only on cliffs and on islets in lakes that trees are seen at all. Grassland.

50. There is a good deal of evidence to show that considerable areas in Ireland were never under forest, but have been occupied by a grassy vegetation throughout the Postglacial period. This appears to be true especially of the centre and west. A progressive change in the composition of the grassland flora may be noted as one passes across Ireland from the rich pastures of Dublin and Meath, growing on deep soil derived from a thick mantle of calcareous Boulder-clay, to the rock-pastures which fringe Galway Bay. In the former areas – for instance, around the famous Hill of Tara, the ancient residence of the kings of Ireland – the grass is dense and luxuriant, and harbours a quite limited number of other plants; while in the vilest the grasses of the cragland are mixed with a nongramineous flora rich in numbers and variety, and of high botanical interest (344, 346, 352, etc.). Over large areas in the centre the subsoil is wet, as along the Shannon, and deep meadow-land prevails, with an admixture of paludal species – Orchidacete, Juncacete, and so on – often a quite rich flora. The vegetation of a very flat area liable to flooding, near Monasterevan, is described in 239. The basalts of Antrim weather into a deep rich clay, with heavy grass; the Coal-measures likewise, but poor, and their rushy calcifuge vegetation is mostly monotonous in the extreme. The Silurian slates of the NE yield a light loam which produces a short sward, with much Agrostis tenuis, Aira caryophyllea, etc., and a flora limited in variety.

51. An average low-level old grassland, well-drained, not particularly calcareous nor the reverse, gave the following list of plants :

Ranunculus acris Hypochaeris radicata
Ranunculus bulbosus Centaurea nigra
Lotus corniculatus Veronica chamaedrys
Trifolium pratense Prunella vulgaris
Trifolium repens Plantago lanceolata
Potentilla anserine Rumex acetosa
Potentilla sterilis Orchis maculata
Heracleum sphondylium Briza media
Pimpinella saxifraga Anthoxanthum odoratum
Galium verum Cynosurus cristatus
Chrysanthemum leucanthemum Dactylis glomerata
Achillea millefolium Holcus lanatus
Senecio jacobaea Festuca rubra
Cnicus palustris Agrostis tenuis
Cnicus pratensis
This was a pasture with a foot of soil overlying flattish esker material containing a good deal of limestone, resting on Silurian rock, a mile west of Dunlavin in Wicklow.

Peat – Bog

52. More than one-seventeenth of the whole area of Ireland is returned as being covered with peat-bog. While mountain bog accounts for a fair share of this, the greater part lies on the lowlands, forming the “red bogs” of the Central Plain. The question of the date and growth of the peat-bogs has already been mentioned (28). While on the mountains decay is often manifest, and the peat and its flora are in places being destroyed by wind and rain, on the plain, while growth has often practically ceased, the only enemy is man; turf-cutting is slowly reducing the characteristic flora, first by drainage and then by the obliteration of the bog by turf-cutting. In areas where bogs were few, as in Dublin and Down, the bog flora is almost extinct; but over the greater part of Ireland it is still abundant and highly characteristic of the country.

The mountain bogs differ from the “red bogs” chiefly in their better drainage and its effects, the most conspicuous of which is the stronger growth of Calluna; but where the mountain bogs are flattish, with pools, the difference in flora is less, and plants like Andromeda, Oxycoccus, Rhynchospora alba, Schoenus and Carex lasiocarpa, typical members of the vegetation of the lowland bogs or swamps, may come up from the plain and colonize them at 1000 to 1500 feet.

53. The great red bogs are very interesting, and form a remarkable feature in the Central Plain. Rising from the edges to the centre, like inverted saucers, they present brown, treeless, smooth tracts, 15 to 25 ft. higher than the surrounding farm-land. Their edges have almost invariably been nibbled into by man, and a floor of peat is often left, used for drying and stacking turf, on which the bog flora has been temporarily destroyed. Rumex acetosella, Holcus mollis, Agrostis tenuis colonize this ground; and on rougher parts Digitalis and other characteristic calcifuge species, Betula alba (verrucosa), Lastrea spinulosa, Osmunda are often abundant*. Turf-cutting drains to a greater or less extent the fringe of the bogs, and encourages the growth of Calluna, while injuriously affecting most of the bog species. Beyond this influence, we get the characteristic bog flora; Calluna, though stunted, is usually dominant; Erica Tetralix, Scirpus ccespitosus, Narthecium, Eriophorum vaginatum, E. angustifolium are abundant, with much Sphagnum, among which ramble the straggling stems of Andromeda and Oxycoccus; and often bosses of Racomitrium uliginosum,. The shallow sinuous pools and depressions are full of Sphagnum, Rhynchospora alba, R. fusca, the three species of Drosera, Menyanthes, Utricularia minor, Carex limosa*.

* See J. M. WHITE: “Re-colonization after Peat-cutting.” Proc. Roy. Irish Acad. 39 B 453-476, Pl. V–IX. 1930.
* See also Irish Top. Bot., pp. xxx-xxxii.
The bogs display here and there, in the midst of their typical vegetation, colonies of relict plants revealing a former condition of the now uniform flora. Thus thin Phragmites, Cladium, Jitneys subnodulosus, or Carex lasiocarpa growing on the bog betray the sites of former lakelets. Sometimes a marked change of vegetation occurs over a limited area which shows perhaps the site of a swallow-hole in the limestone under the bog or other cause of better drainage and less acid and saturated conditions. For instance, among the stunted flora of the large bog where Sarracenia flourishes near Termonbarry in Roscommon (380) is a sudden patch of tall Calluna and Lastrea spinulosa 3 ft. high, with Salix aurita, Rubus idaeus, Menyanthes, Cnicus palustris, Athyrium, Lastrea Filix-mas, L. aristata, Andromeda, Eriophorum, Anthoxanthum, Holcus lanatus – a rather peculiar assemblage.

54. Lists showing the flora of typical small areas of some selected bogs in different parts of the country may be of interest.

Extensive Bog one mile north of Newbridge, Kildare.

This bog represents the most easterly extension of the typical Central Plain “red bogs.” It had a smooth wet surface with many shallow Rynchospora-filled depressions.

Calluna dominant, with much Eriophorum vaginatum, giving a grassy surface. Also:–

Sphagna, c. Aulocomnium palustre, f.
Rhynchospora alba, c. inpools Drosera anglica, r.
Erica Tetralix, f. Eriophorum angustifolium, r.
Narthecium ossifragum, f. Scirpus caspitosus, r.
Drosera rotundifolia, f. Cladonia, r.
The cut-away fringe was invaded by luxuriant Juncus effuses, Lastrea aristata, L. spinulosa, and Pteris.

It will be noted that two of the most abundant plants of the Central Plain bogs – Andromeda and Oxycoccus – are absent here in the east.

Bog near Killashee, Longford. Very smooth surface, with great abundance of Rhynchospora alba.

Rhynchospora alba, v.c. Drosera rotundifolia
Calluna vulgaris, v.c. Drosera anglica
Narthecium ossifragum, v.c. Andromeda polifolia
Rhynchospora fusca, c. Scirpus caespitosus
Erica tetralix Carex diversicolor
Eriophorum angustifolium Lycopodium selago
Bog near Frankford, Offaly. Flora poor and stunted, apparently dying out.
Calluna vulgaris Eriophorum angustifolium
Scirpus caespitosus Narthecium ossifragum
Erica tetralix Drosera rotundifolia
Eriophorum vaginatum Rhynchospora alba
Monmor Bog, Clare. Extensive bog. Surface smooth, with low grassy vegetation. Fully exposed to the Atlantic.
Calluna vulgaris, c. Erica tetralix, f.
Narthecium ossifragum, c. Drosera, 3 species.
Rhynchospora alba, c. Menyanthes trifoliata
Eriophorum vaginatum, c. Orchis maculata
Cladonia rangiferina, c. Scirpus caspitosus
Campylopus fragilis, c. Sphagnum spp.
No pools, and hence absence of Rhynchospora fusca, etc. Great uniformity of vegetation. Occasional patches of Myrica and Molinia. Large Bog by Cashen River, N. Kerry.
Myrica gale dom. Erica tetralix, f.
Rhynchospora alba dom. Orchis maculata
Schoenus nigricans
Narthecium ossifragum, v.c. Molinia caerulea
Drosera, 3 species, c. Cladonia
Eriophorum, 2 species, f. Sphagna
The frequent great abundance of Myrica is a characteristic feature of the Kerry bogs. Analysis of bog vegetation in Connemara, where Molinia moor is the prevailing type, will be found elsewhere (387): and an extended study of the same is in the paper quoted in 385. Some notes on the bog flora of the Dublin mountains appear in PETHYBRIDGE and PRAEGER: “The Vegetation of the District lying south of Dublin” (Proc. Roy. Irish Acad., 25 B 124-180, pl. vii–xi, coloured map). Other useful notes will be found in A. G. TANSLEY and others: “The British Vegetation Committee's Excursion to the West of Ireland” (New Phytol., 1908, 253-260); and R. LI. PRAEGER: “The Flora of Achill Island” (Irish Nat., 1904, 272-3). 55. Where bogs become the site of colonies of breeding gulls a remarkable change in the flora may occur, the trampling and guano of the birds killing out the natural vegetation, their place being taken by a rank vegetation brought by the birds in their crops or on their feet. A study of this as exemplified by a great colony of Black-headed Gulls on a bog near Tullamore in Offaly will be found in “Irish Naturalist,” 1894, 175. 56. The flora of bogs and of their vicinity is sometimes altered by the interesting phenomenon of bog-slides or bog-bursts, whereby a portion of a bog may suddenly discharge its lower semi-liquid portion, leaving the upper crust much fissured and drained, if not actually removed; the ejected material being deposited in a viscid layer at lower points. The chief effect of this occurrence is to encourage the growth of Callluna on the affected area of the bog owing to the improved drainage, and the sites of former flows can be sometimes plainly seen in flattish saucer-shaped depressions with a rough surface and increased amount of Ling. Where farm-land has been covered by the flowing peat, this has been cut for fuel as soon as it has consolidated, and the land restored to its former use.

Ireland is pre-eminently the country of bog-flows, a greater number being recorded from Ireland alone than from the rest of the world. An account of the most catastrophic slide which has happened, with a summary of previous occurrences of the kind, will be found in PRAEGER and SOLLAS: “Report of the Committee . . . to investigate the recent Bog-flow in Kerry” (Sci. Proc. Roy. Dublin Soc., n.s. 8, 475-508, p1. xviii–xix, 1897). Reference may also be made to PRAEGER: “A Bog-burst seven years after” (“ Irish Nat.,” 1897, 20) and “Report on the recent Bog-flow at Glencullin, Co. Mayo,” by A. D. DELAP, A. FARRINGTON, R. LLOYD PRAEGER, and L. B. SMYTH, in Sci. Proc. Roy. Dublin Soc. 20, 181-192. 1932.

Marshes. 57. Before systematic draining dried the land, marshes and swamps occupied much of the surface of Ireland. The deposits of the Ice Age, laid down on the flatter areas irrespective of the previous drainage system, tended to the production of much standing water in the form of shallow lakes. The silting up of these, owing to the formation of marl, accumulation of detritus brought by streams, and vegetable growth, produced many areas of marsh, of which a considerable part still remains, especially in the Central Plain. The wetter undrainable portions form one of the few sanctuaries of an undisturbed flora, since cattle cannot readily penetrate, and they often yield a number of rare plants. The substratum may be acid or alkaline, but it is the marshes on the limestone which yield the more varied and more interesting flora. The presence of lime in wet grassland is mostly made conspicuous at once by the replacement of Juncus effusus by J. inflexus and J. subnodulosus; with them are often much Parnassia, Cnicus pratensis, Orchis maculata, Gymnadenia conopsea, Platanthera bifolia, P. chlorantha, Selaginella; and when the meadow degenerates into marsh, limy or boggy, a taller, coarser vegetation comes in – much Schoenus, Carex lasiocarpa, C. acutiformis, with colonies of Thalictrurm flavum, Lysimachia vulgaris, Epipactis palustris, and sometimes the rare Lathyrus palustris. The edges of pools, which gleam white in summer with limy incrustation, are tenanted by tall groves of Cladium and Phragmites, while in the water Ranunculus circinatus, Potamogeton coloratus, Chara aculeolata, are characteristic species, often heavily incrusted with lime. To give an extreme example, Lough Cloughballymore, 2 miles N of Kinvarra on Galway Bay, consists, in summer at least, of a flat expanse of pinkish limy mud set with stools of Schoenus, patches of thinly spread Cladium and Phragmites, and occasional clumps of Carex Hudsonii, and scarcely any other vegetation.

By some small lakes on the limestone in S Clare, the change from ordinary pasture to water some four ft. in depth was indicated by the following succession of index plants :–

Juncus inflexus
Iris pseudacorus
Juncus subnodulosus
Schoenus nigricans
Carex lasiocarpa
-------------------------------------------------------------------------- Water Level..
Carex inflata
Phragmites communis
Sparganium ramosum
Typha latifolia
Equisetum limosum
Nuphar lutea
In some places in the Central Plain, vegetation has not yet succeeded in colonizing the stretches of marl left bare by drainage, and the latter still extends white and bare, covered along its margin by black peat. Phragmites is usually the first plant to invade it, growing dwarf and sparse.

Around Lough Neagh, marshy land mostly flooded in winter by alkaline or neutral water produces well-marked fen, the flora of which has been lately the subject of careful study*.

* J. SMALL: “The Fenlands of Lough Neagh.” Journ. Ecol. 19 383-388, 1931. T. M. WHITE: “The Fenlands of North Armagh.” Proc. Roy. Irish Acad., 40 B 233-283, P1. VI. 1932.
58. Ireland is essentially a country of lakes, varying from lowland pools or mountain tarns to Lough Neagh, the most extensive area of fresh water in Ireland, and larger than any in Britain. Their number is to be reckoned in thousands rather than hundreds, and in some areas – SW Connemara, the Rosses in Donegal, and the valley of the Erne – there are bewildering networks of land and water. The flora of most of the larger lakes is dealt with in the Topographical Part. In general, it may be said that the pH factor is usually of much importance in relation to the flora. Certain aquatic species are essentially calcicole: Ranunculus circinatus, Potamogeton coloratus, Chara aculeolata, C. tomentosa, are seldom or never seen save in alkaline water. On the other hand, Elatine hexandra, Callitriche intermedia, Lobelia Dortmanna, Juncus bulbosus, Potamogeton polygonifolius, P. obtusifolius, Isoetes lacustris, Nitella translucens, show a marked preference for acid waters. As a consequence, the former group shows in Ireland a decidedly “Central” range, and the latter a decidedly “Marginal” one (41).

The largest lake, Lough Neagh, very open, with shores often sandy, and fed by both acid and alkaline rivers, has a flora peculiar in several respects (463). Most of the major lakes – Loughs Corrib, Mask, Conn, Derg, Ree, Erne, as well as the Lower Lake at Killarney and the lakes a Westmeath, lie mostly or wholly on the limestone; Lough Allen is a notable exception. But many hundreds of smaller lakes, as in Kerry, W Galway, W Mayo, Donegal, Down, Cavan, lie on non-calcareous rocks. They produce a flora which is not encrusted with lime, unlike that of the limestone lakes, and which is much richer in Charophyta, often beautifully clean. Very little dredging has so far been done in any of the Irish lakes, and no doubt the discovery of some new plants and the extension of the range of others will ensue when this has been carried out.

Of special interest is the flora of the turloughs, the lakelets lying on the driftless fissured limestones of the west, which fill in rain and are empty in dry weather. A note on their vegetation is given later (360).

The Calcicole Flora.

59. The calcicole flora finds its best expression on the limy gravels of the eskers of the Central Plain (240-3) and on the limestone crag-lands of the west (346, 352, etc.). Some of the characteristic plants re-appear on the basalts of the NE (455), and limy sea-sands often enable these or others to extend their range far over the non-calcareous rocks, as in S Connemara (386). The ice of Pleistocene times has sometimes pushed calcareous material far over the boundary of the acid rocks, as on the northern slopes of the Dublin mountains (235, 268); and the converse phenomenon also occurs.

On the eskers and limestone pavements of the centre and west the most characteristic and abundant species include Arabis hirsuta, Poterium Sanguisorba, Galium sylvestre, Asperula cynanch,ica, Antennaria dioica, Carlina, Blackstonia, Gentiana Amarella, Ophrys apif era, 0. muscifera, Gyrmnadenia conopsea, Sesleria. The limy marshes and pools, often lying on thick soft calcareous white marl. have also a flora which includes may calcicole plants – Ranunculus circinatus, Thalicrum flavum, Stellaxia glauca, Lathyrus palustris, Myriophyllum verticillatum, Galium uliginosum, Epipactis palustris, Juncus infiexus, J. subnodulasus, Potamogeton coloratus, Scirpus paucifiorus, Carex acutiformis, C. Pseudo-Cyperus, Chara aculeolata. The following are also characteristic of the limestones of the Central Plain:– Hypericum pert oratum, Geranium lucidum, Rhamnus catharticus, Euonymus, Anthyllis, Sorbus Aria segregates, Erigeron acre, Leontodon hispidus, Centourea Scabiosa, Primula veris, Origanum, Anacamptis pyramidalis, Orchis morio, Trisetum, Avena pubescens; many of these are also widely if thinly spread over much of Ireland, finding a sufficiency of alkalies in local sources, on sea sands, and so on.

It may be noted that while distinctly calcicole in Ireland, many of these plants would not enter into this category in countries on the Continent, and some not even in England. This is a well-known phenomenon, due presumably to the fact that with increase of precipitation neutral soils tend to become acid owing to the accumulation of humus compounds, driving basiphilous and neutrophilou plants to the limestone in order to escape from inimical edaphic conditions. (See also 61.)

The penetration into outlying limestones or limy-soil areas by the characteristic Central Plain flora offers some points of interest. Two of the most marked cases are the Killarney lakes and E Down. Killarney (320) and the band of limestone that zigzags northward from it is cut off from the broken-up edge of the Central Plain limestones by a minimum of 20 miles of hilly Coal-measures and Devonian slates: E Down (477) has 40 miles of Silurian slates between it and the nearest tongue of the main area of Carboniferous limestone, and only a quite small and local outcrop of this rock; yet both possess a number of the most characteristic calcicoles of the Central Plain flora (see 322, 477). The converse is seen in the much commoner phenomenon• of the presence of a characteristic calcifuge flora on even quite small outcrops, from under the limestone, of slates or sandstones, as is well exemplified in the minor foldings in the southern portion of the Central Plain, where inliers of this nature are frequent. These cases merely illustrate the dictum of A. R. Wallace, that plants have misted long enough to have been carried to all suitable localities, and the determining factor in their distribution is to be found in their power of adaptation to their new conditions.

The continuity of the calcicole flora in the Central Plain is much obscured by the abundance of peat-bog on the limestone, with its essentially calcifuge flora. Distribution-maps of species, say by counties, may thus be very misleading, just as the presence of limy shell-sands in areas of acid rocks upsets the continuity of the calcifuge flora when mapped except in a very detailed manner.

The range of the calcicole flora has been extended, as mentioned below (75), by the use of lime mortar in walls, which has allowed some of the calcicole ferns, for instance, to spread into every part of the country.

The most remarkable calcicole flora in Ireland is that which colonizes the bare limestone “crags,” “dints,” or “pavements” which stretch with little interruption from Lough Carra in Mayo south to Askeaton in Limerick, and attain their main development in the Burren region of Clare, on the S side of Galway Bay (Plates 19, 23) They yield a number of plants unknown elsewhere in Ireland, and an amazing profusion of some others rare in the country. They offer a surprising mixture of types, from Mediterranean (e.g., Neotinea) to Arctic-alpine (e.g., Dryas). Their flora is dealt with especially in 346, 352, and also in 338, 344, 359-363, 365, etc.

The lowlying parts of this area are characterized by turloughs-depressions in the limestone which fill with water in wet weather by subterranean passages, and empty by the same means. They yield a peculiar flora (characterized especially by Viola stagnina), which is referred to in 360.

The Calcifuge Flora.

60. The calcifuge flora occupies a much wider range of geological formations than the calcicole. While the latter attains its main development on the Carboniferous limestone and soils derived from it (the Chalk of NE Ireland being too limited in area to have more than a quite slight effect), calcifuge plants find a home equally on the wide areas of metamorphic rocks (NW and W Ireland), granite; (E especially), Silurian slates (NE), Devonian sandstones and slates (S), and Coal-measure shales (SW, etc.). The Central Plain is in fact ringed round with a calcifuge flora. This is of two types – the, familiar peat flora, found equally in the Central Plain and elsewhere, and the flora of non-calcareous soils, wide-spread outside the Central Plain wherever peat is absent, and occupying in characteristic form the lowlands such as those orN Kerry (Coal-measures), Cork (Devonian), Wexford and Down (Silurian), Donegal (metamorphic). Here we find abundance of:–

Ranunculus hederaceus Jasione montana
Lepidium heterophyllum Vaccinium Myrtillus
Raphanus raphanistrum Digitalis purpurea
Polygala serpyllacea Stachys arvensis
Spergula vulgaris Teucrium Scorodonia
Montia fontana Polygonum Hydropiper
Hypericum humifusum Rumex Acetosella
Radiola linoides Juncus squarrosus
Cytisus scoparius Juncus bulbosus
Cytisus Gallii Potamogeton
Lotus uliginosus Juncus polygonifolius
Lathyrus montanus Scirpus fluitans
Cotyledon umbilicus Deschampsia flexuosa
Veneris Sedum anglicum Nardus stricta
Peplis Portula Blechnum Spicant
Galium saxatile Athyrium Filix-foemina
Gnaphalium uliginosum Lastrea aristata
Chrysanthemum segetum Equisetum sylvaticum
Senecio sylvaticus
It is to be noted that old woods on the limestone, with a humus soil, tend like bogland to introduce a calcifuge flora as islands. This applies for instance to the occurrence of Scilla non-scripta and some of the ferns.

The general change of vegetation observed as one passes from non-calcareous to calcareous soils is illustrated in 472 by contrasting the flora of the NE Silurian area with that of the Carboniferous limestone to the south of it.

Where the drift is absent at the junction of the alkaline and acid rocks, as about Lough Corrib and Lough Mask, the abrupt change of flora may form a very remarkable and striking feature (371). The same phenomenon is seen on a grand scale in the contrasting floras of the N and S shores of the deep indentation of Galway Bay – on one side the brown heath vegetation of the vast bogs of Connemara with its rare Ericacem, etc. (385, 386); on the other the gaunt grey limestone hills of Burren with Sesleria dominating a gramineous formation, also full of rare and interesting plants (346-350).

61. Sometimes there are found puzzling transgressions between the calcicole and calcifuge floras in areas markedly acid or alkaline as regards their rocks. The presence of a large group of calcicole plants on the metamorphic area of SW Connemara, referred to elsewhere (388), is sufficiently accounted for by the highly calcareous nature of the sea-sands in the vicinity; but the explanation of the presence of Erica cinerea and Calluna on bare limestone tracts here and there is not so obvious, and, like the other cases quoted below, calls for a series of close observations and chemical experiments not yet carried out. A few other exceptional occurrences of calcifuge plants on limestone, or vice versa, may be quoted:–

At the E base of Keshcorran in Sligo, on drumlins formed of limestone drift lying on the Limestone Plain, Cytisus, Digitalis, Blechnum, Athyrium, and other characteristic calcifuge species flourish; here, probably, the lime has been leached out of the soil in which the plants grow (382).

On scarps of Yoredale sandstone in the Carrick district of Fermanagh, Sesleria, Arabis hirsuta, Asplenium Rutamuraria, all conspicuous calcicoles, grow mixed with such calcifuge species as Vaccinium Vitis-Idcea, V. Myrtillus, Calluna, Erica, Digitalis, and Blechnum (438). About New Ross the calcicole Origanum, Sedum acre, Ceterach, and the caleifuge Erica cinerea, Sedum anglicum, etc., grow together on Gotlandian slates (259). The strongly calcicole Euphrasia salisburgensis furnishes other examples (344). Of the Galway – Clare calcicoles, Neotinea has been found at Mount Gable near Cong on the metamorphic rocks, and also on the Coal-measures near Ennistymon 6 to 8 miles from the nearest limestone; Gentiana verna flourishes on peaty banks on similar shales between Ballyvaughan and Lisdoonvarna, amid a calcifuge vegetation.

Near Corco Gap in Maam Turk Saxifraga spathularis, Athyrium, and Blechnum grow with Asplenium Rutamuraria in dry almost soil-less chinks of primitive limestone. On L. Corrib and L. Cullin the last-named flourishes in chinks of wave-washed slates and gneisses.

In these and similar cases actual soil-analysis alone can throw light on the relations between plant and substratum, and this has not yet been done. But it is clear that the question is seldom simple. To calcicolous plants the attraction of the limestone may be its chemical qualities, or its physical: and the upper layers (d a limy soil may be neutral or even acid, owing to leaching or to the accumulation of humus. See for instance E. J. SALISBURY: The “Significance of the Calcicolous Habit” (Journ. Ecology, 8 202-215, 1921 – with good bibliography).

Coasts.

62. There is a rather marked contrast betweeen the seaside flora of the E and W sides of Ireland. That of the E coast is much the richer, attaining its optimum in Wicklow and Wexford (272), and including among its rarer members Matthiola sinuata, Trifolium glomeratum, Diotis, Asparagus, Glyceria Borreri, and the endemic Equisetum Moorei. The cause of the difference between E and W is partly edaphic, in the larger amount of gravelly and sandy beaches which prevail in the east, and partly climatic, in the very great exposure prevailing on the western sea-board. Quite a number of E coast plants – for instance, Thalictrum dunense, Trigonella, Trifolium glomratum, T. scabrum, T. subterraneum, Inula crithmoides, Diotis, Atriplex maritima, Asparagus, Scilla verna, luncus acutus, some of them widely spread there – do not venture into the west, or at most make a rare and tentative appearance in Donegal or Kerry.

On the other hand, very few maritime plants prefer the W coast. Cochlearia groenlandica, which ranges from Antrim to W Cork, appears to be the only well – marked example.

The poverty of maritime species in the west is illustrated by the sand – dune plants much more than by those inhabiting rocks or salt-arshes. While in some favoured spots in the west, as on the Mullet, at Strandhill in Sligo, and Killala in West Mayo, we find well-developed dunes, backed by undulating stable moss-grown sandy ground, in other parts the sands are reduced by exposure to mere deserts. The great tracts beyond Bunowen in SW Connemara, at Keel strand in Achill, and on North Inishkea will serve as examples. These large level areas are quite bare of vegetation, or support a miserably poor and starved flora. But even where the sands are well colonized, the characteristic flora is much reduced as compared with the east. Among the dunes we miss the blue spires of Echium, the grey leaves of Cynoglossum; Thalictrum dunense, Lychnis alba, Trifolium arvense are likewise absent from the sands. Lycopsis, Euphorbia portlandica, E. Paralias are quite rare; and on the beaches, Cakile, Eryngium maritimum, Salsola, Polygonum Raii are but seldom found. The sand is often blown up adjoining hill-sides to a height of several hundred feet; elsewhere, as at Keel Lough in Achill, its advance has dammed the natural drainage and flooded a considerable extent of country, or has buried houses and demesne lands, as at Dunfanaghy and Rosapenna in Donegal.

Semi-exposure to the Atlantic sometimes produces the phenomenon of a salt-marsh flora at the foot of a storm-beach of boulders, as below Mountcharles on Donegal Bay, where a sward of Glyceria maritima with Limonium humile and Atriplex occupies such a position.

The flora of the western sea-rocks and cliffs, as contrasted with the east coast, compares favourably with it, yielding, in addition to all the common species, such plants as Spergularia rupicola in abundance, Lavatera, Limonium binervosum, and other local species.

On the cliff-ranges (and down to sea-level on beaches) Sedum roseum joins the maritime group, and is often profuse, with quantities of Angelica, Eupatorium, Matricaria inodora, Beta, and other rank-growing species on the damp ledges. The salt-marsh flora is likewise similar to that of the E coast, but rather poorer.

63. Plantago Sward. – One of the most distinct formations of the extreme west is a very close dwarf maritime sward, occupying wind-swept cliff-tops and exposed slopes by the sea, composed mainly, often almost wholly, of Plantago maritima and P. Coronopus, growing extremely small. As noted on Clare Island*, this association consists mainly of the two species named, with P. lanceolata, Thymus Serpyllum, and Euphrasia, and in small quantity nearly thirty other species, all forming a dense sward about ½-inch in height, with flower-stems (even of the taller species like Scabiosa succisa and Hypochaeris), rising about 2 inches). Radiola grows ½-inch high, usually unbranched; Ophioglossum the same height, and barren. The flowers of the majority of the plants rise level with those of Angallis tenella and Radiola. At the west end of Inishkea. Plantago sward, consisting almost entirely of the two species first named, growing extremely minute, covers a considerable area; it forms a shining green carpet, so close that no lawn-mower, however close-set, could cut a leaf off it, and as smooth to the hand as a newly-ironed table-cloth. Plantago sward is characteristic of areas of particularly great exposure close to the sea. It occurs all along the W coast, and ranges from sea-level to about 400 feet.

* R. LL. PRAEGER: “The Flora of Clare Island.” Irish Nat., 1903, 281.
64. The occurrence of maritime plants in alpine or inland situations in Ireland is a feature almost confined to the western mountains, from W Cork to Donegal, the species involved there being Cochlearia officinalis (alpina), Silene maritima, Armeria maritima (not planifolia), Plantago maritima. Cochlearia extends to the Galtees, in the southern midlands; in Derry the fine cliff of Benevenagh shelters all four species (as also Cerastium semidecandrum), and Silene continues along the basaltic scarp to Cave Hill overlooking Belfast. In the west, P. maritime has in addition a wide inland range over the low limestones and along the shores of Loughs Derg (up to 25 miles from the sea), Corrib, Mask, Carra, Conn, etc. Rather unexpected also is the occurrence of Carex distans in two stations near Tuam in NE Galway. The Lakes of Killarney harbour a curious outlier of the maritime flora, embracing Silene maritima, Cerastium semidecandrum, Arnieria maritima, and Asplenium marinum. The most interesting inland outlier of the maritime flora is on L. Neagh, where are found Viola Curtisii, Spergularia rupicola, Cerastium semidecandrum, Erodium cicutariuni, Trifolium arvense, Plantago maritime, Scir pus maritimus, S. Taberncemontani, and Carex extensa (see 464). Most of these are elsewhere in Ireland exclusively maritime.

Islands.

65. The islands off the west coast – e.g., Inishbofin, Inishturk, Clare I. – offer some points of interest. They have larger floras than most equal areas of the adjoining mainland, insularity being more than compensated by the variety of habitat which they afford. None of them possesses any limestone. They are less smothered in bog than the mainland, and tend to yield drier soils – and I believe have a smaller rainfall, though this has not been fully tested*. Frost and snow are practically unknown. The mean annual range of temperature is only about 15i° F. The following points regarding their flora may be mentioned:–

  1. They furnish, owing to limy sands or lime-built walls, a home for some calcieole plants, e.g., Arabis Brownii, Centaurea Scabiosa, Ophrys apifera (all on Bofin), Ceterach (on Bofin and Clare I.).
  2. They possess a few representatives of the Lusitanian and American groups – Saxifraga spathularis is on all three, S. Geum (in a hybridized state) and Erica mediterranea on Clare I., Euphorbia hiberna on Turk, Eriocaulon on Bofin.
  3. They offer refuges for some plants very sparsely distributed in Ireland, some of them probably relictHelianthemum guttatum on Bofin and Turk (elsewhere only in Cork), Orobanche rubra and Cephalanthera. ensifolia on Clare I., Calamagrostis epigejos and Lycopodium inundatum on Bofin. These would appear to be at least local relicts, swamped out of their parent stations on the mainland by the spread of the overmastering peat.
  4. Their flora shows an interesting mixture of plants of great exposure and others of damp shady places. Thus all three islands possess Cochlearia grwnlanclica, Sedum roseum, Juniperus sibirica, Lastrea cemula, Athyrium Filixfcemina, all growing close to sea-level.
Achill is not included in the above comparison, as it is scarcely separated from the mainland.

The Great Blasket, a desperately exposed high narrow ridge of slate, has Cochlearia grcenlandica, Saxifraga spathularis, Lastrea CrMitia, Athyrium, Hymenophyllum peltatum,, and as an index to the degree of oceanic influence, Asplenium marinum on walls at 750 ft. above the sea (329). The Aran Islands, large reefs mostly of bare fissured limestone, yield a very different flora, of high interest (352).

* See W. J. LYONS: “Climatology,” In Biological Survey of Clare Island, Proc. Roy. Irish Acad., 31, part 6. 1914.
Mountains.

. 66. The mountainous areas in Ireland are situated mainly in the maritime counties, the only exception of importance being the fine range of the Galtees (3015 ft.) rising from the rich limestone plain of southern Tipperary. A number of other hill-groups – mostly NE and SW ridges – have been formed, like these, by folding, which has brought up the underlying Devonian and Silurian slates and sandstones; this results in wide heathery moorlands, but the hills do not generally rise high enough to effect much other change in the vegetation, which is usually of a conventional calcifuge type. Wicklow possesses the largest continuous area of high land (over 200 sq. m. are above 1000 ft.), with Lugnaquilla rising to 3039 ft., but like that other fine eastern range, the Mourne Mountains in Down (2796 ft.), it is poorer in alpine plants than many lower and smaller areas in the west. Thus, Slieve League in Donegal (1972 ft.) yields on a quite restricted area more plants of alpine type than Wicklow and Down taken together. The Irish mountain-groups are formed of granites, schists, slates, sandstones, and shales, mostly of pre-Permian age (the Eocene Mournes being a marked exception). The only limestone mountains are the interesting Ben Bulben group – a plateau standing up some 2000 ft. (fig. 24), with cliff-walls rich in alpine plants. An upland somewhat similar to the last in being cliff-walled and yielding a rich flora of calcicole proclivities, is formed by the Eocene basalts of Antrim and Londonderry. In view of the perennial interest of “alpines,” the mountain plants are dealt with rather fully in the Topographical Section below, and only a few general considerations need detain us here.

In the first place, the Irish alpine flora is poor. But the general scarcity of alpine plants need not diminish the interest of mountain botanizing. “It may sound like a paradox” writes one of the most critical of Irish botanists* “to say that the botanical survey of an Irish mountain region derives a peculiar zest from the very poverty of our flora in alpine species. Yet the assertion may be made with perfect truthfulness. That the rapture of discovery varies directly with the rarity of the object sought for, that the value of the thing attained is measured by the labour of attainment – these are time-honoured truisms in every system of proverbial philosophy; and their essential truth is daily borne in upon the mind of the botanist who devotes himself to the exploration of any of the mountain-groups of Ireland. The fans of the Alpine Club-moss, which he spurns with callous feet on the slopes of Snowdon, he half worships when they meet his longing eyes in the Wicklow or Kerry highlands; and so with many others of our alpine species – unconsidered trifles abroad, they become for him objects of enthusiasm at home.”

* N. COLGAN: “Botanical Notes on the Galway and Mayo Highlands.” Irish Nat., 1900, 111-118.
67. Out of 67 species comprising Watson's “Highland” type in Britain, 42 occur in Ireland*. This is a not unduly small number when we consider especially the area and height of mountainous country in Scotland and Wales; but in Ireland the plants are mostly thinly distributed and rare. Seven of the rarest – Arabis petraea, Alchemilla alpina, Rubus chamaemorus, Saxifraga nivalis, Epilobium alsinefolium, Carex pauciflora, Poa alpina, have only eleven stations between them all. Against this, the following are relatively much more widespread in Ireland than in Britain (but it is to be noted that in Ireland all of them but Salix herbacea descend to sea-level, and attain their increase of range not by their abundance on the mountains, but by widespread occurrence on the lowlands:–

* In addition, there is in Ireland Arenttria ciliata on the Ben Bulben range, 1000-1950 ft., unknown in Britain; and Euph,rasia salisburgensis, recently found in Yorkshire, which Watson would have included in his Highland type: it is in western Ireland widespread and mainly quite lowland (to sea-level) though ascending to 1000 ft. on Ben Bulben.
Juniperus sibirica Carex aquatilis
Dryas octopetala Sesleria caerulea
Hieracium anglicum Selaginella selaginoides
Hieracium iricum Isoetes lacustris
Salix herbacea
The “Highland” plants of Watson as a group do not in Ireland fit well with his definition, “Species chiefly seen about the mountains.” Much less do they constitute the alpine flora in this country. Taking the Highland Type flora as set down in “Cybele Hibernica,” p. xliv (the Hieracia are a difficulty, and one may for convenience accept the compromise there used), we find that 16 of the 42 occur down to sea-level, often not in the proximity of mountains. These are :–
Draba incana Hieracium gothicum
Dryas octopetala Arctostaphylos Uva-ursi
Saxifraga oppositifolia Vaccinium
Saxifraga aizoides Juniperus sibirica
Sedum roseum Carex aquatilis
Galium boreale Sesleria ccerulea
Hieracium anglicum Selaginella selaginoides
Hieracium iricum Isoetes lacustris
Sixteen more come in before the 1000 ft. contour is exceeded :–
Thalictrum alpinum Hieracium strictum
Subularia aquatica Polygonum viviparum
Silene acaulis Oxyria digyna
Saxifraga stellaris Salix herbacea
Epilobium alsinefolium Carex rigida
Saussurea alpina Carex pauciflora
Hieracium prenanthoides Cryptogramme crispa
Hieracium senescens Asplenium viride
Between 1000 and 2000 ft. seven more have appeared:–
Arabis petraea Poa alpina
Saxifraga nivalis Polystichum Lonchitis
Alchemilla alpina Lycopodium alpinum
Rubus Chamaemorus
and no less than twelve more have died out.

No new species appears above 2000 ft. except Deschampsia alpina, and of the 21 plants which continue upwards all but eight:–

Saxifraga stellaris, 3400
Sedum roseum, 3150
Oxyria digyna, 3130
Salix herbacea, 3050
Carex rigida, 3300
Deschampsia alpina, 3370
Poa alpina, 3100
Asplenium viride, 3150
are gone when 3000 ft. is reached. (The figure attached to each shows its extreme limit.) These last are all on Macgillicuddy's Reeks. It is to be remembered that the Reeks (Carrantual 3414 ft.) is the only range that exceeds 3000 by more than at most 127 ft. The accompanying graph (fig. 9) exhibits the increase in the number of “Highland” plants on the Irish hills up to a maximum at 1000-1200 ft., and their steady diminution with greater elevation.


FIG. 9. – IRISH ALPINE PLANTS IN RELATION TO ELEVATION.

68. As regards their general distribution in Ireland, the “Highland” plants tend, like the mountains, to be marginal. With a maximum in the N, they range down either coast – much more plentifully over Ben Bulben and the Mayo-Galway highlands into Kerry than over the Mournes into Wicklow. The height at which they occur increases from N to S, and is greater in the E than in the W. Comparing the Donegal-Derry area with Kerry-Cork (data for 17 species are available), we find that the “Highland” plants common to both have a mean lower limit in the N of 550 ft., which rises in the S to about double that amount. This is one of the few definite effects of latitude that one can find in the Irish flora.

A similar comparison of the behaviour of the “Highland” plants of west and east – of the Mayo-Galway mountains with those of Down-Wicklow – shows a corresponding decrease in elevation towards the west. Of 25 species in the western area and 18 in the eastern, 13 are common to both, of which data are available for 12. These 12 show a mean lower limit of 1070 ft. in Down-Wicklow, Mid of 720 ft. in Mayo-Galway. This effect is climatic, and illustrates the manner in which the whole flora is depressed in altitude on account of the conditions prevailing on the Atlantic sea-board.

69. None of our mountains is high enough to reach the region of an alpine-plateau vegetation. Indeed, the summits, commonly covered with peat, are usually very poor in alpines compared with rocky scarps on the flanks of the hills, especially where the latter face northward. Taking the highest points in Donegal (2466 ft.), Down (2796), Sligo (2115), Mayo (2688), Wicklow (3039), Tipperary (3015), and Kerry (3414), we find that the average summit-flora numbers about 16 species, of which not more than two are usually alpines. These figures remain very uniform all over Ireland. The prevailing summit plants are species of wide vertical range, all descending to sea-level :–

Potentilla erecta Luzula sylvatica
Galium saxatile Eriophorum vaginatum
Vaccinium Myrtillus Deschampsia cespitosa
Calluna vulgaris Anthoxanthum odoratum
Rumex Acetosella Festuca ovina
Empetrum nigrum Lycopodium Selago
Juncus squarrosus
The alpines which may occur with these on the summits named are Saxifraga stellaris, Vaccinium vitis-idaea, Salix herbacea, Carex rigida, and Lycopodium alpinum.

The nearest approaches to an alpine sward are found here and there in exposed ground in the west – on Curraun Achill, at about 1200 ft., where Arctostaphylos Uva-ursi, Empetrum, and Juniperus sibirica form a dense carpet and on the Meenawn range on Achill Island, where a very close sward formed mainly of Calluna and the three species before mentioned, with a little Salix herbacea, occupies the ground at 1300-1500 ft. But indeed an almost equally alpine faeies is supplied by the sheets of Arctostaphylos Uva-ursi, Dryas, Gentiana verna, Sesleria, that in Burren range from over 1000 ft. down to sea-level, though mixed with such southern types as Neotinea and Adiantum (see Plate 2).

For a brief account of the alpine flora of each mountain-range, see the Topographical Part below.


Introduction and Preface; 1-26: Geography, Topology, Climate; 27-47: General history of the flora ;
48-69: Vegetational sub-divisions; 70-78: Human Influence and Botanical workers;
79-219: Some Interesting Plants;