COUNTRYSIDE COUNCIL FOR WALES
SITE OF SPECIAL SCIENTIFIC INTEREST: CITATION
ANGLESEY
CRAIG WEN/CORS CASTELL
National Grid Reference: SH494807
Site area: 22.1 ha
This site is selected as an example of lowland acidic heathland habitat and base rich fen.
In damp sections of the heathland, heather Calluna vulgaris and cross-leaved heath Erica tetralix are the dominant ericaceous shrubs with deer-grass Trichophorum cespitosum, purple moor-grass Molinia caerulea, bog asphodel Narthecium ossifragum and creeping willow Salix repens as frequent associates; in drier areas both bell heather Erica cinerea and western gorse Ulex gallii are abundant. Two uncommon heathland plant species, marsh gentian Gentiana pneumonanthe and pale heath violet Viola lactea, both of which have declined over recent years in Britain, are present.
The heathland grades into wetland associated with springlines, streams and basin mire. Extensive areas of fen are covered by black bog rush Schoenus nigricans and blunt flowered rush Juncus subnodulosus. This species rich plant community includes grass of Parnassus Parnassia palustris, early marsh orchid Dactylorhiza incarnata and lesser clubmoss Selaginella selaginoides. Slender sedge Carex lasiocarpa, bottle sedge Carex rostrata and Cladium mariscus are locally dominant in the wetter parts of the mire. Small areas of limestone grassland are also present.
The North Wales Naturalists' Trust manage 6.5 hectares of this site as a nature reserve.