Pethybridge & Fraeger— Vegetation South of Dublin. 161 



Many of the rest of these perennials have deciduous leaves in which 

 xerophytic cliaracters are less pronounced, such as in Vacciniuyn Myr- 

 ttUiis^ in which the green twigs remain above ground after the leaves 

 have fallen. In Listera cordata, Narthecium ossifragum, Pteris Aquilina^ 

 not only is the whole of the summer foliage lost, hut the stems of the 

 plants pass the winter underground. The leaves of Pteris, as is now 

 well known, ^ are very plastic in structure, and in exposed places show 

 xerophytic characters, while under other conditions they may be of the 

 shade type. The leaves of the Bog Asphodel {Narthecium) are of the 

 isobilateral type, standing in a vertical plane, and are thus, as Warming 

 points out,^ of a xerophytic nature. On the other hand, Listera cordata 

 is essentially a shade-loving species, and its leaves are not xerophytic 

 m character; and the same may be said of Oxalis Acetosella, though here 

 a few leaves may be found on plants in sheltered positions through- 

 out the winter. 



As regards the grasses and sedges, these may be practically 

 regarded as deciduous ; for while some of the leaves are on the jjlants 

 throughout the winter, they are, as a rule, undeveloped, and well 

 protected by the dead blades and sheaths of the previous summer's 

 growth. ^Nevertheless, the leaves of many of these at least show 

 xerophytic characters, well seen, for instance, in JVardus, Festuca ovina^ 

 Scirpiis ccespitosus, and the two Cotton-grasses. 



Composition of Calluna Association. 

 Number of stations examined — nine. 



Calluna vulgaeis. 9. 

 juncus squakeosus. 8. 

 Vaccinium Myetillus. 8. 

 Naedus steicta. 8. 

 Carex binervis. 7. 

 Potentilla Toementilla. 6. 

 Eeica cineeea. 6. 

 Galium saxatile, 6. 

 Luzula maxima. 5. 

 Scirpus cfEspitosus. 5. 



Sphagnum spp. 5. 

 Ageostis vulgaeis. 4. 

 Pestuca ovina. 4. 

 Blechnum Spicant. 4. 



Polygala depressa. 1. 

 Oxalis Acetosella. 1 . 

 Ulex Gallii. 3. 

 Pyrus Aucuparia. 1 . 

 Scabiosa succisa. 1. 



' Boodle, Linn. Soc. Journal, Bot., vol. xxxv,, 1904, p. 6o9. 

 - Warming, " Lehrbuch der okologischeu rtlanzengeographie," 1896, 

 pp. 175, 183. 



