140 Plant-formation of Siliceous Soils 



Old Bed Sandstone (cont. } : 

 Trieliomanes radieans 

 AspleQium acutum 



Arbutus Unedo appears to show no special soil pro- 

 clivities at Killarney, occurring not only on both, sandstone 

 and limestone, but also both in the shallow soil of dry 

 rocky woods and in the deeper soil of damp almost 

 marshy hollows. It grows considerably more luxuri- 

 antly than in the Mediterranean "maquis," the finest 

 trees reaching a girth of 8 feet (2'4 m.) or in extreme 

 cases 14 feet (4'2 m.). This is probably owing to the fact 

 that its growth is not checked by the hot dry Mediterranean 

 summers. The common character of the two habitats is 

 of course the mild winter, the mean January temperature 

 of Killarney being nearly the same as that of the Riviera. 



The present range of the species in the Killarney 

 region extends over an area roughly 6 miles (c. 9"7 km.) 

 north and south by about 3 miles (c. 4'8 km.) east and 

 west, excluding outljnng stations where a few trees still 

 exist as remnants, probably, of woods long since disap- 

 peared. There can be no doubt that the arbutus has 

 much decreased both in abundance and in the extent of 

 its Irish area, even in comparatively modern times. Thus 

 Dr Smith, whose History of Kerry was published in 1756, 

 makes constant references in that work to the recent 

 destruction of this tree in large quantities for smelting 

 purposes, as well as by a disastrous fire which caused 

 great havoc among them; while if place-names can be 

 relied on as a clue to its former distribution, the arbutus 

 appears to have extended to Co. Clare and even as far 

 north as Co. Mayo, where an island in Clew bay derives 

 its name from the tree. 



Of the other plants occurring in the same woods 

 Saxifraga Geum and Pinguicula graiidiflora are confined, 

 within the British Isles, to the south-west of Ireland, 

 Saxifraga umbrosa is confined to Ireland and is mainly 



