BOTANICAL FEATURES OF IRELAND xxxiii 



hills of Old Red Sandstone, and dropping 97 feet in 18 miles, 

 reaches sea-level at Limerick, where it widens into a great estuary. 

 One plant of the Shannon — Inula salicina — is in the British 

 Isles restricted to the shores of Lough Derg. Another, Chara 

 tomentosa, is elsewhere in these islands confined to the lakes of 

 Westmeath. A third, Scirpus triqueter, which inhabits the tidal 

 waters in abundance, is to be reckoned among the rarest British 

 plants. The most characteristic plant of the Shannon is Teucrium 

 Scordium ; it ranges from Roosky in Leitrim to Limerick, and is 

 most abundant on the expansions of Ree and Derg ; elsewhere in 

 Ireland it is known only from one lake in Clare. On the rocky 

 limestone shores of the river-lakes a rich and peculiar flora prevails ; 

 the following plants are characteristic : — 



Thalictrum collinum. Chlora perfoliata. 



Geranium sanguineum. Gentiana Amarella. 



Rhamnus catharticus. Teucrium Scordium. 



Rubus csesius. Juniperus communis. 



Pamassia palustris. Ophrys apifera. 



Galium boreale. Sesleria cserulea. 



Carlina vulgaris. Selaginellaselaginoides. 

 Hieraciimi umbellatuni. 



Plants of the Lakes. — The peculiar flora of the river-lakes of 

 the Shannon has been dealt with in the preceding paragraph. Of 

 similar character is the flora of the shores of the large western 

 lakes — Lough Corrib, Lough Mask, and Lough Conn. These all 

 lie along the western edge of the Central Plain, and their margins 

 are formed chiefly of limestone rocks. When Lough Erne is reached 

 we have passed beyond the range of several of the more conspicuous 

 plants of the limestone lake-shores, and a less striking flora prevails. 



In the north-east. Lough Neagh, the largest lake in the British 

 Isles, offers some points of interest. Two species are in Ireland 

 confined to its shores — Carex Buxhaumii and Calamagrostis stncta ; 

 both being exceedingly rare in Great Britain, and characteristic of 

 northern Europe. A group of plants usually maritime in their 

 habitat also attracts attention: — Scirpusmaritimiis, S. Tahernamontani, 

 Spergularia rupestris, Viola Ciirtisii, Erodium cicutarium, Trifolium 

 arvense. The open sandy character of the shores may sufficiently 

 account for the presence of the last three. As to the others, when 



B.I. A. PKOC, SEB. in., VOL. VII. C 



