Decbmbeb, 1901.] 



KNOWLEDGE. 



283 



England have a wide distribution — such ai'o the Flix- 

 ■weod (S if yiiihri 11)11 Sophia), TrifoliKin ijlomeratiiiii and 

 T. gcahnini, Trigoiielhj ornithopudioiJef, Senecio eriici- 

 foliiii'. ;md the trrass Fi'fliK-a iiiniilitmis. The cakicolo 

 group is poorly represented ; ;uid plants of cultivation 

 — denizens and colonists — occur in profusion. Generally 

 speaking, the flora of this ai-ea resembles that of the 

 iwljoining portions of Great Britain, as might be ex- 

 pected from its position, and from the similarity of 

 physical conditions. No doubt the plants peculiar to 

 this eastern shore-lino reached Ireland with numbei-s of 

 others across the former land-connexion from Englanil, 

 but being less adaptable, they remained and colonized 

 this region, while hai-dier species pushed westwaid ; 

 possibly some of them were among the latest arrivals, 

 and found their passage westward disputed by stronger 

 species which already occupied the ground. 



The North-east. — The pcculiai-ities of this area ai'e 

 mainly geological. In Eocene times a period of great 

 volcanic activity resulted in the formation of bed upon 

 bed of lava, which eventually formed a high plateau 

 covering the greater part of Antrim and Derry, and 

 extending fai- over the present North Channel. This 

 plateau, now much reduced in extent, dislocated and 

 weather-worn, still forms a wide ai-ea^ of high heathery 

 hills, fringed with steep escarpments, and intersected 

 with deep-car\'ed valleys, in which the decayed lava has 

 formed a rich soil. Climate has also influenced the 

 flora. Phytologically and zoologically, this is the ex- 

 treme north of Ireland, rather than Donegal, though 

 the latter re;iches a higher latitude. In Donegal the 

 influence of the warm Atlantic currents is clearly felt ; 

 in the north-east both land and sea are colder. Then 

 there is, besides, the proximity of Scotland, allowing of 

 easy colonization in times of former land-connexion. 

 So we should expect to find here, and we actually do 

 find, that certain northern and chai-acteristically 

 Scottish plants form a marked feature of the flora, such 

 as Sagina giibulafa, Arenaria verna. Geranium sylvaticum, 

 Viria ^ylvalica, Circxa alpina, several species of Pyrola, 

 Melampyniiii gylvaticmti, Orobanche rubra, Equisehnn 

 prafense. But while Antrim possesses a larger number 

 of plants of this type than any other portion of Ireland, 

 it is worthy of note that most of the Scottish type plants 

 have a wide though often discontinuous range in 

 Ireland. With Antrim, Deixy and Donegal as head- 

 quarters, they spread chiefly down the west coast, de- 

 creasing eastward, and reaching their minimum in the 

 south-east. Physical conditions no doubt account in 

 part for this distribution, but further reasons are needed 

 'to explain the paucity of these plants on the highlands 

 and rough ground of, for instance, Wicklow and 

 Waterford. 



The Limestone Plain. — The wide stretch of low land 

 which occupies the centre of Ireland extends from the 

 Irish Sea at Dublin to the Atlantic Ocean at Galway, 

 and northward and southwai-d for fifty miles in either 

 direction. It consists of an almost unbroken area of 

 Carboniferous limestone; whatever newer rocks may 

 have been at one time or another laid down on this 

 ancient floor have been removed by denudation, so that 

 now the deposits of the Glacial epoch, and the great 

 turf bogs, alone cover its nakedness. In the west/ large 

 areas are actually devoid of all covering, and present 

 to the eye grey wildernesses of gnarled and fissured 

 rock. The centre is largely occupied by huge swelling 

 bogs,' while green sinuous esker-ridges give a peculiar 

 character to the scene; and in the east the glacial 

 deposits are especially well developed. A number of 



lai'go lakes ai'c irregularly distributed. Though 

 characterized by an absence of most of those species 

 which form the loiuling features on the ca.st and west 

 coasts, the flora of this lai'go area is tolerably iioiiio- 

 geneous, and has a riiaracter of its own. In the first 

 phvce, the great prcdoniiiKuice of limestone has its duo 

 effect, calcicole plants forming a conspicuous feature ; 

 and the quantity of lake and marsh produces a large 

 vai'iety of hicustrine and paludal species. Lighl^soil 

 species are few, and chiefly haunt the esker-ridges; and 

 plants of the uplands axe almost wanting. The great 

 bogs, fomied entirely of vegetable matter, are a most, 

 striking feature. These presumably arose around springs 

 on the limestone floor, which provided a perennial 

 supply of moisture. The patch of marsh plants around 

 such a spring increased in size, and by its growth tended 

 to retain the water; presently bog plants, such as Bog- 

 mosses {S2>ha(jinim), Bog-bean, Bog Asphodel, Bog- 

 Cotton, established themselves; the spring was soon 

 buried, but fed the colony from beneath. It spread 

 steadily. The more rapid growth of the central wetter 

 parts caused its surface to eventually assume the form of 

 an inverted saucer set on a flat table ; the formation of a 

 felty crust allowed of the gi-owth of Ling, Crow-berry, and 

 other heath plants. The shelly deposits underlying the 

 bogs show that often they have originated around lakes, 

 which they have filled up and covered over with a deep 

 deposit of peat; the straggling stunted patches of 

 Phrari mites, Cladium, and such plants, not bog plants 

 proper, which one sometimes finds far out on the great 

 bogs, are very possibly the surviving remnant of a 

 buried lake-flora. The flora of the bogs varies according 

 to the amount of moisture present in the surface layer. 

 On the wettest bogs, among a luxuriant growth of .S'/'/'".'/- 

 num, we find the Cranberi-y, Bog-bean, White Beak- 

 rush, the sedge Carer, limiim, and the various Sundews. 

 The bog of average wetness has a flora composed chiefly 

 of Ling, Bell-Heather, Mai-sh Andromeda, Bog Asphodel, 

 Bog-Cotton, Scirjius caspifosiin, with Sundews and White 

 Beak-i-ush along the pool-margins. On the driest bogs 

 the Ling grows exuberantly ; Bracken and Birch, and 

 even Brambles, put in an appearance, and most of the 

 plants in the previous list disappear. Where the peat 

 is drained and the original vegetation destroyctl, as 

 where the bog has been cut for fuel, {plants of quite 

 another kind, such as Senerio aylvaticus, Rume.r 

 Acetose/la, and Aira caryopliyllca, colonize the ground. 

 Whether wet or diy, the bog-soil is quite free from 

 lime, even when resting on limestone, and supports 

 many strongly calcifuge plants. In striking contrast to 

 the bogs with thoir peculiar plant-association, and often 

 interspersed between them, wo have the limestone pave- 

 ments and limestone lake-shores of the western low- 

 lands. The bare rock occupies a large portion of the 

 surface ; but in the cracks and crevices the grax^lual 

 dissolution of the limestone and of vegetable matter 

 has caused a rich soil to collect, which supports a highly 

 interesting flora. Of its most peculiar members con- 

 sideration must bo reserved until the next paragraph. 

 Curiously enough, many of the characteristic plants are 

 not by any means in their general distribution especially 

 partial (o limestone — such, for instance, are the Bloody 

 Craiie'.s-bill, Thnliclrum roJliiiuni, the Madder, Bcar- 

 beiry, Mountain Avcns ; and some reason other than 

 their calcareous surroundings must be sought to account 

 for their remarkable abundance here. 



The South and West Coasts.— Speaking generally, 

 the conditions prevailing along the west coast of Ireland 

 are as follows : — The country is formed of old rocks, 



