10 io 



Proceedings of the Royal Irish Academy. 



europaeus, Orchis pyramided/is, and Juncus glaums, which, though occurring 

 throughout Ireland, are in "West Mayo local, owing to the rarity of limestone, 

 and would not be expected to occur on these Silurian islands. 



Common Plants Absent from the Thp.ee Islands. 



Barbarea vulgaris. 

 Eropbila vulgaris. 

 Eeseda Luteola. 

 Silene Cucubalus. 

 Sagina apetala. 

 Cytisus scoparius. 

 Medicago lupulina. 

 Rubus Idaeus. 

 Geurn urbanum. 

 Rosa tomentosa. 

 Hippuris vulgaris. 

 Epilobium birsutum. 

 Smyrniuni Olusatrum. 

 Siurn angustifolium. 

 Viburnum Opulus. 

 Asperula odorata. 

 Seabiosa arvensis. 

 Bidens cernua. 

 Petasites officinalis. 

 Crepis paludosa. 

 Linaria Cymbalaria. 



Scropbularia nodosa. 

 Melampyrum pratense. 

 Nepeta Glecboma. 

 Salicornia berbaeea. 

 Suaeda maritima. 

 Rum ex nemorosus. 

 Alnns glutinosa. 

 Salix Caprea. 

 Habenaria bifolia. 

 Typba latifolia. 

 Sparganium simplex. 

 Arum maculatum. 

 Potamogeton perfoliatus. 

 Carex disticba. 

 C. remota. 

 C. birta. 



Alopecurus pratensis. 

 Briza media. 

 Bromus giganteus. 

 Equisetmn sylvaticum. 



To this list might be added Rumex conglomerate, of which a single plant 

 occurred on Clare Island and another on Inishbofin, both, no doubt, casually 

 introduced. 



If we examine this list, we may extract from it certain little groups of 

 plants which will help us to appreciate its character and significance. 



Trees and Sheubs. — Cytisus scoparius, Ruhus Idaeus, Rosa tomentosa, 

 Viburnum Opulus, Alnus glutinosa, Salix Caprea. For the absence of these 

 we must look, perhaps, to the great exposure of the islands; also to the 

 merciless way they are grazed. Some of the arboreal species which are found 

 on the islands occur extremely sparingly — Crataegus Oxyacantha as one bush 

 on Inishturk ; Pyrus Mains as one bush on Clare Island. If any of the 

 missing species formerly occurred as sparingly as these do now, grazing might 

 easily have exterminated them. 



