214 BRITISH PLANTS 



limestone cliffs in Sligo ; Simethis bicolor, Kerry and Devon ; 

 and Inula salicina, found only on the shores of Lough 

 Derg, in Gal way. 



More remarkable still, a few plants are found in the 

 west of Ireland and not elsewhere on the continent of 

 Europe. They occur, however, in North America, and 

 it has been suggested that they may have travelled over 

 that lost continent, Atlantis, which some people have 

 supposed once stretched across the Atlantic between 

 Europe and America. It is pretty certain, however, that 

 in pre-glacial times land did extend in that direction, 

 running from the north of Scotland to Iceland and Green- 

 land, and from Greenland to the mainland of America. 

 Along this highway the horse possibly travelled into 

 Europe, for this animal is American in origin, and with 

 it might have come plants, of which three only stOl 

 remain to tell the tale. These American plants are : 

 Spiranthes Romanzoviana, west of Ireland ; Eriocaulon 

 septangulare, Connemara and the Hebrides ; and Sisy- 

 rinchium angustifolium, a plant allied to the iris, found 

 in the west of Ireland. 



Last of aU we have that rare and extremely beautiful 

 filmy fern, Trichomanes radicans, the Killarney fern, 

 which occurs in a few places in the wet, shady recesses of 

 rocks near the Lakes of KiUarney, in North Wales, and 

 in the Isle of Arran. Elsewhere it is found only in the 

 Azores, the Canary Islands, and the island of Madeira. 



English Plants absent from the Irish Flora.— While 

 some plants are found in Ireland, and nowhere else in 

 Great Britain, there are others unknown in Ireland which 

 are quite common in England. Among them are the 

 following : 



Black bryony (Tamus communis), white bryony {Bryonia 

 dioica), herb-paris {Paris quadrifolia), snowdrop, lily-of- 

 the- valley, butcher's-broom, hop, wayfaring-tree (Vibur- 

 num Lantana), mistletoe, wild service-tree {Pyrus tor- 

 minalis), Ulex minor, traveller's-joy {Clematis Vitalba), 

 and Myosurus minimus, the mousetail. 



The absence of these plants from Ireland is, in most 

 cases, due to the fact that Ireland was separated from 

 Great Britain before the latter was separated from the 

 Continent, so that many species must have arrived in 

 England too late to cross over into Ireland. Eor this 



