170 



Proceedings of the Royal Irish Academy. 



The Juncus Associations. (J.) 



Rushes form the dominaut species in at least two associations 

 which are found on different kinds of ground. The first of these 

 may he distinguished as the Juncus- Poly trichum association. Where 

 springs on the hill- sides produce sloping wet patches or lines, Juncus 

 communis^ often intermixed with J. acutiflorus, grows in luxuriant 

 groves, with a dense undergrowth of lax bright green Sphagmm, 

 and Polytrichum growing a foot high. This association has, 

 like Pteris, a considerable vertical range, being found high up 

 on the Calluna moors (to nearly 2,000 feet), and thence descending 

 in green lines or broad beds well down into the Ulex Gallii area. At 

 a distance, especially in the moorland zone among Calluna^ the islands 

 which this association forms stand out conspicuously in spring and 

 summer by their greenness, and in winter by their greyness. The 

 flora is everywhere limited and uniform, and the following list will 

 show its average composition : — 



Composition of Juj^cus- Sphagnum Association. 

 Number of statio7is examined — four. 



Juncus communis. 4. 

 Sphagnum sp'p. 4. 

 Juncus acutiflorus. 4. 

 Polytrichum. 4. 

 Potentilla Tormentilla. 4. 

 Holcus mollis. 3. 

 Agrostis vulgaris. 3. 

 Galium saxatile. 3. 

 Juncus squarrosus. 2. 



Carex stellulata. 2. 

 Kumex Acetosa. 2. 



Ranunculus Plammula. 1 . 

 Calluna vulgaris. 1. 

 Pedicularis sylvatica. 1. 

 Eriophorum angustif olium. 1 . 

 Carex vulgaris. 1 . 

 jS"ardus stricta. 1 . 



This association forms also a fairly conspicuous fringe along the 

 edges of the high level Military Road, which rises to 1,600 feet. This 

 is due to the alteration in drainage caused by the presence of the road 

 itself. Running parallel to it, on its east side, is an almost continuous 

 and more or less regular water-channel, which receives the drainage 

 from the Calluna slopes above. At several spots the water from this 

 channel flows under, and sometimes over, the road, and thus the wet 

 side of the road also has a considerable fringe of rushes. At those 



