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Saturday 21 JUNE 2014                   

vartry reservoir

LEADERS: catriona Brady

The Reservoir Flora

A perfect midsummerís day morning saw seven members join the leader, Catriona Brady for this meeting at the scenic Vartry Reservoir to look at plants along the shoreline and its fringes and view the adjacent oak, birch and elder woodland.
 
The Vartry Reservoir is the result of a project initiated in the mid-19th century by Sir John Gray, Chairman of the Dublin Water Works Committee, to respond to the urgent need for improvement to Dublin cityís water supply.  To ensure the success of the plan, Sir John Gray bought up all the land needed, thereby preventing speculators and when the project was secure, he sold it to Dublin Corporation for exactly what he had paid for it.   His statue, erected in his honour by public subscription, stands in OíConnell Street at its junction with Abbey Street.  The reservoir remains a major source of water for Dublin city, serving Wicklow and Bray en route.
 
The Vartry River flows south from its source on Sugar Loaf Mountain to supply the reservoir.  Leaving the reservoir at its southernmost point, it flows through The Devilís Glen, Mount Usher Gardens and Broad Lough to enter the sea at Wicklow town as the Leitrim River.
 
The deciduous woodland of interest for the outing lies at the north end of the Vartry reservoir, about half a kilometre south-east of Sallyís Bridge.  Catriona noted that, although a lot of the trees appear planted, some are quite old.  The evident age of the large stands of Elder (Sambucus nigra), a species very seldom seen as a full-size tree in woodland, is particularly unusual.  Not generally used in planting, the elder may have been part of original hedgerows and grows with Downy birch (Betula pubescens) and some Mountain ash (Sorbus aucuparia) above an understory where Bramble (Rubus sp.) and Broad buckler fern (Dryopteris dilatata) are dominant.  The elder carries Jewís ear fungus (Auricularia auricula-judae) and the Pedunculate oak (Quercus robur) hosts a profusion of the Marble gall (Andricus kollari).  The woodland generally bears little sign of regeneration.
 
The tall orchid species growing in some numbers at the shady entrance to the woodland was identified as Heath-spotted Orchid (Dactylorhiza maculata).   The adjacent wetland yielded Yellow flag (Iris pseudacorus), Floating sweet-grass (Glyceria fluitans) and Water horsetail  (Equisetum fluviatile), with Amphibious bistort (Polygonum amphibium)  looking fully aquatic in the water nearby.  False oat-grass (Arrhenatherum elatius), Yorkshire fog (Holcus lanatus), Greater Birdís-foot trefoil (Lotus pedunculatus),  Tormentil (Potentilla erecta), Oval sedge (Carex ovalis), Meadow sweet (Filipendula ulmaria), Creeping bent (Agrostis stolonifera), Tufted hair-grass (Deschampsia cespitosa), Bitter vetchling (Lathyrus linifolius) and Heath bedstraw (Galium saxatile) were noted in the grassland along the woodland edge.  Common skullcap (Scutellaria galericulata) grew scattered through the grassland near the lake-shore, with Marsh pennywort (Hydrocotyle vulgaris), Shoreweed (Littorella uniflora) and Mint (Mentha sp.)  in the waterís edge.
 
Further along towards the north end of the reservoir, an area of damp grassland subject to seasonal inundation yielded Carnation sedge (Carex panicea), Bottle sedge (Carex rostrata), Green-ribbed sedge (Carex binervis), Pill sedge (Carex pilulifera), Black sedge (Carex nigra), Heath wood-rush (Luzula multiflora), Cuckoo flower (Cardamine pratensis),  Common cottongrass (Eriophorum angustifolium) and more Common skullcap (Scutellaria galericulata).  Yellow rattle (Rhinanthus minor) and Germander speedwell (Veronica chamaedrys) grew on the dry hummocks here. 
 
Retracing its steps along the shore back to the starting point, the group added Common spike-rush (Eleocharis palustris) and Lesser spearwort (Ranunculus flammula)  to the dayís haul.

Pauline Hodson

  

Vartry Reservoir Lakeshore

   

Mixed Woodland                                             Birch Woodland

      

Lakeside Grasses                                 Field Club                                 Deschampsia cespitosa

       

Carex nigra                         C. panicea                              C. echinata                         C. rostrata

   

Eleocharis palustris  Equisetum fluviatile     Dryopteris dilatata

     

Dactylorhiza maculata (Heath-spotted orchid)

         

Potentilla erecta               Ranunculus flammula              Rhinanthus minor 

               

Small Heath                                 Andricus kollari                              Sambucus nigra

        

Haemopsis sanguisuga

    Photographs © Pat Lenihan

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