Caeau Pen-y-coed

Site of Special Scientific Interest · 52.9674, -3.1580

Geology & landscape

Geological Period: Silurian

Description

Description Caeau Pen-y-coed is of special interest for its unimproved neutral grassland which is associated with areas of acidic grassland and other habitats including mature woodland, scrub and bracken. Caeau Pen-y-coed comprises of a series of 11 contiguous fields occupying the northern flank of a low hill approximately 1 km to the south east of the centre of Llangollen. The site ranges from 110 m to 200 m in altitude and overlooks the town, with urban housing to the north and the mixed coniferous and broadleaved woodland of Pen-y-coed to the south. The solid geology of the site consists of calcareous shales (Silurian Period) that are overlain by well-drained slightly to very stony brown soils. These circumneutral brown soils support areas of the now uncommon crested dog’s-tail Cynosurus cristatus common knapweed Centaurea nigra grassland, meadow vetchling Lathyrus pratensis sub-community. This community was the major grassland type of traditionally managed hay meadows and pastures throughout the lowlands of Britain. The grasses most commonly found are red fescue Festuca rubra, crested dog’s tail, and common bent Agrostis capillaris along with sweet vernal grass Anthoxanthum odoratum, cock’s-foot Dactylis glomerata and Yorkshire-fog Holcus lanatus. Herbs present in the sward include those indicative of unimproved grassland such as common bird’s-foot trefoil Lotus corniculatus, rough hawkbit Leontodon hispidus and meadow vetchling. The site also supports areas of dry acidic (calcifugous) grassland and include small stands of the nationally uncommon bitter-vetch Lathyrus montanus, betony Stachys officinalis sub-community of sheep’s fescue Festuca ovina, common bent, heath bedstraw Galium saxatile grassland. These are floristically similar to the adjacent areas of neutral grassland sharing several of its more prominent grasses and herbs, among them common bent, sweet vernal-grass, common knapweed and common bird’s-foot trefoil, and are distinguished primarily by the presence and often abundance of sheep’s fescue Festuca ovina, devils-bit scabious Succisa pratensis and bitter-vetch. Small areas of the more mesotrophic Yorkshire-fog -white clover Trifolium repens sub-community of this grassland are also present as well as patches dominated by wavy hair-grass Deschampsia flexuosa, with frequent to abundant heath bedstraw and bilberry Vaccinium myrtillus. Caeau Pen-y-Coed includes associated stands of mature woodland, scrub and bracken which form an integral part of the site and add to the structural and ecological diversity of the habitat mosaic.

Species mentioned

English name
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Latin name
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IUCN / Red List Type Family
common bent Agrostis capillaris LC grass poaceae
sweet vernal grass Anthoxanthum odoratum LC grass poaceae
crested dog's tail Cynosurus cristatus LC grass poaceae
cock's foot Dactylis glomerata LC grass poaceae
wavy hair grass Deschampsia flexuosa Not listed in GB list grass poaceae
sheep's fescue Festuca ovina LC grass poaceae
red fescue Festuca rubra LC grass poaceae
Yorkshire fog Holcus lanatus LC grass poaceae
black knapweed Centaurea nigra LC herb asteraceae
heath bedstraw Galium saxatile LC herb rubiaceae
bitter vetchling Lathyrus montanus Not listed in GB list herb fabaceae
meadow vetchling Lathyrus pratensis LC herb fabaceae
rough hawkbit Leontodon hispidus LC herb asteraceae
birdsfoot trefoil Lotus corniculatus LC herb fabaceae
betony Stachys officinalis Not listed in GB list herb lamiaceae
devils-bit scabious Succisa pratensis VU herb caprifoliaceae
white clover Trifolium repens LC herb fabaceae
billberry Vaccinium myrtillus LC shrub ericaceae

Insects to look out for

These moths, butterflies and beetles are known to feed on plants recorded at this site, and carry a notable UK conservation status — but a host-plant being present doesn't mean the insect has actually been recorded here. Treat this as "worth watching for," not a confirmed sighting.

SpeciesStatusVia host-plant
Speckled footman
Coscinia cribraria
Critically Endangered Vaccinium myrtillus
Black-veined moth
Siona lineata
Critically Endangered Centaurea nigra, Lotus corniculatus
New forest
Zygaena viciae
Critically Endangered Lathyrus pratensis, Lotus corniculatus
Straw belle
Aspitates gilvaria
Endangered Lotus corniculatus
Wood white
Leptidea sinapis
Endangered Lathyrus pratensis, Lotus corniculatus
Slender scotch
Zygaena loti
Endangered Lotus corniculatus
Mouse moth
Amphipyra tragopoginis
Vulnerable Lotus corniculatus
Broom moth
Ceramica pisi
Vulnerable Vaccinium myrtillus
Mottled umber
Erannis defoliaria
Vulnerable Vaccinium myrtillus
Dingy skipper
Erynnis tages
Vulnerable Lotus corniculatus
Marsh fritillary
Euphydryas aurinia
Vulnerable Succisa pratensis
Satyr pug
Eupithecia satyrata
Vulnerable Centaurea spp., Galium spp.
Garden dart
Euxoa nigricans
Vulnerable Trifolium spp.
Grayling
Hipparchia semele
Vulnerable Festuca ovina, Festuca rubra
Bedstraw hawk-moth
Hyles gallii
Vulnerable Galium spp.
Silver studded blue
Plebejus argus
Vulnerable Lotus corniculatus
Early moth
Theria primaria
Vulnerable Vaccinium myrtillus
Pale eggar
Trichiura crataegi
Vulnerable Vaccinium myrtillus
Flounced chestnut
Agrochola helvola
Near Threatened Vaccinium myrtillus
Beaded chestnut
Agrochola lychnidis
Near Threatened Trifolium spp., Vaccinium myrtillus
Large nutmeg
Apamea anceps
Near Threatened Dactylis glomerata
Latticed heath
Chiasmia clathrata
Near Threatened Lathyrus pratensis, Trifolium repens, Trifolium spp.
Small heath
Coenonympha pamphilus
Near Threatened Agrostis spp., Cynosurus cristatus, Festuca spp.
Rosy marsh moth
Coenophila subrosea
Near Threatened Vaccinium myrtillus
The Silurian
Eriopygodes imbecilla
Near Threatened Galium saxatile, Vaccinium myrtillus
Autumnal rustic
Eugnorisma glareosa
Near Threatened Festuca ovina, Galium spp.
Grey pug
Eupithecia subfuscata
Near Threatened Centaurea spp.
Silver-spotted skipper
Hesperia comma
Near Threatened Festuca ovina
Scarce forester
Jordanita globulariae
Near Threatened Centaurea nigra
Wall
Lasiommata megera
Near Threatened Agrostis spp., Dactylis glomerata, Holcus lanatus
Rosy minor
Litoligia literosa
Near Threatened Dactylis glomerata, Festuca ovina
Dark-barred twin-spot carpet
Xanthorhoe ferrugata
Near Threatened Galium spp.
Scotch burnet
Zygaena exulans
Near Threatened Vaccinium myrtillus

Host-plant data: Cook et al. (2025), Traits data for the butterflies and macro-moths of Great Britain and Ireland, 2024, UK Centre for Ecology & Hydrology / Butterfly Conservation; and Padovani et al. (2020), Database of Insects and their Food Plants (DBIF), UK Centre for Ecology & Hydrology (both Open Government Licence). Contains data supplied by UK Centre for Ecology & Hydrology.

Plant communities

W20 — Montane scrub

Salix lapponum-Luzula sylvatica scrub

Matches 8 species from the description above: Agrostis capillaris, Anthoxanthum odoratum, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Galium saxatile, Succisa pratensis, Vaccinium myrtillus

Salix arbuscula, Salix cinerea, Salix lapponum, Salix myrsinites, Salix phylicifolia, Salix reticulata, Empetrum nigrum, Calluna vulgaris, Salix lanata, Vaccinium myrtillus, Vaccinium uliginosum, Carex atrata, Carex bigelowii, Carex binervis, Carex flacca, Luzula multiflora, Luzula sylvatica, Huperzia selago, Selaginella selaginoides, Aulacomnium palustre, Mnium hornum, Philonotis fontana, Plagiomnium undulatum, Rhizomnium punctatum, Dicranum bonjeanii, Dicranum majus, Dicranum scoparium, Fissidens adianthoides, Racomitrium lanuginosum, Calliergonell cuspidatum, Ctenidium molluscum, Hylocomium splendens, Hypnum callichroum, Hypnum cupressiforme, Palustriella commutatum, Plagiothecium denticulatum, Plagiothecium undulatum, Pleurozium schreberi, Ptilium crista-castrensis, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Rhytidiadelphus triquetrus, Sanionia uncinata, Scorpidium revolvens, Thuidium tamariscinum, Atrichum undulatum, Polytrichastrum alpinum, Sphagnum capillifolium, Sphagnum fallax, Sphagnum girgensohnii, Sphagnum palustre, Sphagnum russowii, Sphagnum squarrosum, Sphagnum subnitens, Sphagnum teres, Barbilophozia barbata, Chiloscyphus polyanthos, Diplophyllum albicans, Lophocolea bidentata, Plagiochila porelloides, Ptilidium ciliare, Scapania undulata, Cladonia squamosa, Peltigera canina, Angelica sylvestris, Caltha palustris, Hieraclium spp., Saussurea alpina, Solidago virgaurea, Campanula rotundifolia, Succisa pratensis, Valeriana officinalis, Rhodiola rosea, Vaccinium vitis-idaea, Thymus praecox, Epilobium anagallidifolium, Dactylorhiza viridis, Euphrasia officinalis, Rhinanthus minor, Oxalis acetosella, Oxyria digyna, Polygonum viviparum, Rumex acetosa, Anemone nemorosa, Ranunculus acris, Thalictrum alpinum, Alchemilla alpina, Alchemilla glabra, Filipendula ulmaria, Geum rivale, Galium boreale, Galium saxatile, Saxifraga aizoides, Saxifraga hypnoides, Saxifraga oppositifolia, Saxifraga stellaris, Viola riviniana, Agrostis canina, Agrostis capillaris, Anthoxanthum odoratum, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Nardus stricta, Dryopteris dilatata, Phegopteris connectilis

W25 — Bracken scrub

Pteridium aquilinum-Rubus fruticosus underscrub

Matches 6 species from the description above: Agrostis capillaris, Anthoxanthum odoratum, Dactylis glomerata, Festuca rubra, Galium saxatile, Holcus lanatus

Hedera helix, Acer pseudoplatanus, Fagus sylvatica, Quercus robur, Fraxinus excelsior, Sambucus nigra, Ulex europaeus, Crataegus monogyna, Prunus spinosa, Luzula multiflora, Mnium hornum, Brachythecium rutabulum, Kindbergia praelonga, Angelica sylvestris, Conopodium majus, Heracleum sphondylium, Arum maculatum, Cirsium arvense, Lonicera periclymenum, Silene dioica, Stellaria holostea, Mercurialis perennis, Geranium robertianum, Glechoma hederacea, Teucrium scorodonia, Hyacinthoides non-scripta, Chamerion angustifolium, Circaea lutetiana, Digitalis purpurea, Rumex acetosa, Anemone nemorosa, Ficaria verna, Potentilla erecta, Rosa arvensis, Rosa canina, Rubus fruticosus agg., Rubus idaeus, Galium aparine, Galium mollugo sens.lat., Galium saxatile, Urtica dioica, Viola riviniana, Agrostis capillaris, Anthoxanthum odoratum, Arrhenatherum elatius, Dactylis glomerata, Festuca rubra, Holcus lanatus, Holcus mollis, Poa trivialis, Pteridium aquilinum, Dryopteris dilatata, Dryopteris filix-mas

W22 — Hedgerow scrub, Mixed scrub

Prunus spinosa-Rubus fruticosus scrub

Matches 4 species from the description above: Agrostis capillaris, Dactylis glomerata, Festuca rubra, Holcus lanatus

Hedera helix, Acer campestre, Corylus avellana, Ulex europaeus, Prunus spinosa, Plagiomnium undulatum, Brachythecium rutabulum, Eurhynchium striatum, Kindbergia praelonga, Thuidium tamariscinum, Atrichum undulatum, Lophocolea bidentata, Achillea millefolium, Cardamine flexuosa, Lonicera periclymenum, Moehringia trinervia, Silene dioica, Silene uniflora, Stellaria media agg., Mercurialis perennis, Geranium robertianum, Stachys sylvatica, Teucrium scorodonia, Hyacinthoides non-scripta, Oxalis acetosella, Digitalis purpurea, Plantago lanceolata, Veronica chamaedrys, Armeria maritima, Rumex acetosa, Filipendula ulmaria, Geum urbanum, Rosa canina, Rubus fruticosus agg., Rubus idaeus, Galium aparine, Urtica dioica, Viola riviniana, Agrostis capillaris, Brachypodium sylvaticum, Dactylis glomerata, Festuca rubra, Holcus lanatus, Holcus mollis, Poa trivialis, Asplenium scolopendrium, Pteridium aquilinum, Dryopteris borreri, Dryopteris filix-mas

W21 — Hedgerow scrub, Mixed scrub

Crataegus monogyna-Hedera helix scrub

Matches 2 species from the description above: Dactylis glomerata, Holcus lanatus

Hedera helix, Salix cinerea, Acer pseudoplatanus, Ilex aquifolium, Betula pendula, Corylus avellana, Fagus sylvatica, Quercus robur, Fraxinus excelsior, Malus sylvestris, Sorbus aria, Taxus baccata, Ulmus glabra, Ulmus procera, Sambucus nigra, Viburnum lantana, Euonymus europaeus, Cornus sanguinea, Juniperus communis, Ligustrum vulgare, Clematis vitalba, Rhamnus cathartica, Crataegus laevigata, Crataegus monogyna, Prunus spinosa, Juncus effusus, Plagiomnium undulatum, Brachythecium rutabulum, Kindbergia praelonga, Rhynchostegium confertum, Tamus communis, Heracleum sphondylium, Torilis japonica, Arum maculatum, Arctium minus, Cirsium arvense, Lonicera periclymenum, Moehringia trinervia, Silene dioica, Stellaria graminea, Stellaria holostea, Stellaria media agg., Calystegia sepium, Mercurialis perennis, Geranium robertianum, Iris foetidissima, Glechoma hederacea, Lamium purpureum, Origanum vulgare, Stachys sylvatica, Teucrium scorodonia, Allium ursinum, Hyacinthoides non-scripta, Circaea lutetiana, Rumex sanguineus, Anemone nemorosa, Ranunculus repens, Fragaria vesca, Geum urbanum, Potentilla sterilis, Poterium sanguisorba, Rosa arvensis, Rosa canina, Rubia peregrina, Rubus fruticosus agg., Galium aparine, Urtica dioica, Viola riviniana, Anisantha sterilis, Arrhenatherum elatius, Brachypodium pinnatum, Brachypodium sylvaticum, Bromopsis erecta, Dactylis glomerata, Elytrigia repens, Holcus lanatus, Holcus mollis, Poa trivialis, Asplenium scolopendrium, Pteridium aquilinum, Dryopteris filix-mas