156 



Proceedings of the Royal Irish Academy. 



a colonist in the domain of these plants, and in direct antagonism to 

 them. Observations show that even in the case of the robust and 

 aggressive U. europmis^ Pteris is not only able to hold its own, but can 

 push back its rival. In several places where these two plants come 

 into contact, we have had occasion to observe that the front rank of 

 the Gorse is almost dead, consisting of old spindly plants struggliDg 

 upward for light, quite bare below, and devoid of young growth or 

 seedlings. In early spring, when the victorious Bracken is represented 

 only by a bed of decaying debris, the shattered front of the Gorse 

 presents a very curious appearance. Pteris also appears to be able to 

 colonize new ground more quickly than either species of Ulex. On 

 the hill-slopes, where land has passed out of cultivation, the fence 

 marking the limit of former tillage often also marks a strong 

 boundary between Pteris and U. Gallii, the former having been first 

 to get into the abandoned ground, and the U. Gallii, which would 

 normally be dominant on the area in question, having been unable to 

 oust it. 



The conditions under which the dependent species of the Pteris 

 association live, differ from those obtaining in tlie domain of Ulex or 

 Callima, in that the dominant species is deciduous. The undergrowth, 

 richly fed with humus, is in winter open to the sky ; but during the 

 summer season sliaded under the arching canopy of fronds. The 

 conditions resemble those which obtain in deciduous woods, and a 

 number of vernal woodland plants are present. In May the Bracken 

 areas often exhibit glorious sheets of blue, white, and yellow, due to 

 abundance of Scilla tiutans, Viola sylvatiea, Veronica Chamcedrys, 

 Anemone nemorosa, Oxalis Acetosella^ Conopodium denudatum, Ranun- 

 culas Ficaria^ Primxda vulyaris. Owing to our work having been 

 perforce largely carried on during the winter months, this feature of 

 the Pteris association is understated in our statistics. 



Composition of Pteris Association. 



Number of stations examined— four . 



Ptekis Aquilina. 4. 

 Agrostis vulgaris. 4. 

 Galium saxatile. 4. 

 Potentilla Tormentilla. 4. 

 Yiola sylvatiea. 4. 



Rumex Acetosa. 4. 

 Crataegus Oxyacantha. 3. 

 Rubus fruticosus. 3. 

 Lonicera Periciymenum. 3. 

 Scabiosa succisa. 3. 



