Glanfedw

Site of Special Scientific Interest · 52.3670, -3.8632

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Dyfed County

Geology & landscape

Geological Period: Silurian

Description

Description Glanfedw is of special interest for its species-rich neutral grassland, which has a long recorded history of traditional management. The site is located on the upland fringe about 1 km to the south-west of Devil’s Bridge, and comprises two small fields on a moderately sloping north-east facing hillside, at an altitude of 260-300m. The underlying soils are neutral to acidic brown earths of the Denbigh Series (mull phase); they are shallow and generally free-draining. The bedrock geology is dominated by a sequence of interbedded mudstones and sandstones belonging to the Lower Silurian (Llandovery Series) Devil’s Bridge Formation. Species-rich neutral grassland occupies the bulk of each enclosure. The principal species here are red fescue Festuca rubra, crested dog’s-tail Cynosurus cristatus and common bent Agrostis capillaris, accompanied by common bird’s-foot trefoil Lotus corniculatus and common knapweed Centaurea nigra. In the larger field the presence of plants such as heath-grass Danthonia decumbens, devil’s-bit scabious Succisa pratensis and tormentil Potentilla erecta, along with scattered sheep’s fescue Festuca ovina and common dog-violet Viola riviniana on the steeper slopes, indicates links to a more acidic form of grassland. Amongst the more frequent associates are harebell Campanula rotundifolia, burnet-saxifrage Pimpinella saxifraga and eyebright Euphrasia officinalis agg. In the smaller field rough hawkbit Leontodon hispidus is particularly abundant. Small areas of dry acid grassland occupy the steep banks above the farm-house and in the north-western part of the smaller field. This grassland contains prominent sheep’s-fescue Festuca ovina and heath bedstraw Galium saxatile and is punctuated by scattered rowan Sorbus aucuparia, hawthorn Crataegus monogyna and patches of western gorse Ulex gallii. Small flushes around the margins of the site support marshy grassland characterised by frequent purple moor-grass Molinia caerulea and sharp-flowered rush Juncus acutiflorus. Locally uncommon grassland plants found at Glanfedw include adder’s-tongue fern Ophioglossum vulgatum, smooth lady’s-mantle Alchemilla glabra, and pale sedge Carex pallescens.

Species mentioned

English name
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Latin name
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IUCN / Red List Type Family
adders-tongue fern Ophioglossum vulgatum LC fern ophioglossaceae
common bent Agrostis capillaris LC grass poaceae
crested dog's tail Cynosurus cristatus LC grass poaceae
heath grass Danthonia decumbens NT grass poaceae
sheep's fescue Festuca ovina LC grass poaceae
red fescue Festuca rubra LC grass poaceae
purple moor grass Molinia caerulea LC grass poaceae
lady's mantle Alchemilla glabra LC herb rosaceae
harebell Campanula rotundifolia LC herb campanulaceae
black knapweed Centaurea nigra LC herb asteraceae
English sticky eyebright Euphrasia officinalis LC herb orobanchaceae
heath bedstraw Galium saxatile LC herb rubiaceae
rough hawkbit Leontodon hispidus LC herb asteraceae
birdsfoot trefoil Lotus corniculatus LC herb fabaceae
burnet saxifrage Pimpinella saxifraga NT herb apiaceae
tormentil Potentilla erecta LC herb rosaceae
devils-bit scabious Succisa pratensis VU herb caprifoliaceae
common dog violet Viola riviniana LC herb violaceae
sharp-flowered rush Juncus acutiflorus LC rush juncaceae
pale sedge Carex pallescens VU sedge cyperaceae
hawthorn Crataegus monogyna LC shrub rosaceae
western gorse Ulex gallii LC shrub leguminosae
rowan Sorbus aucuparia LC tree rosaceae

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
High brown fritillary
Fabriciana adippe
Critically Endangered Viola riviniana
Black-veined moth
Siona lineata
Critically Endangered Centaurea nigra, Lotus corniculatus
New forest
Zygaena viciae
Critically Endangered Lotus corniculatus
Straw belle
Aspitates gilvaria
Endangered Lotus corniculatus
Pearl-bordered fritillary
Boloria euphrosyne
Endangered Viola riviniana
Chequered skipper
Carterocephalus palaemon
Endangered Molinia caerulea
Figure of eight
Diloba caeruleocephala
Endangered Crataegus spp.
The lappet
Gastropacha quercifolia
Endangered Crataegus monogyna
Wood white
Leptidea sinapis
Endangered Lotus corniculatus
Scarce vapourer
Orgyia recens
Endangered Crataegus spp.
Slender scotch
Zygaena loti
Endangered Lotus corniculatus
Mouse moth
Amphipyra tragopoginis
Vulnerable Crataegus spp., Lotus corniculatus
The sprawler
Asteroscopus sphinx
Vulnerable Crataegus spp.
Large heath
Coenonympha tullia
Vulnerable Molinia caerulea
Mottled umber
Erannis defoliaria
Vulnerable Crataegus spp., Sorbus aucuparia
Dingy skipper
Erynnis tages
Vulnerable Lotus corniculatus
Marsh fritillary
Euphydryas aurinia
Vulnerable Succisa pratensis
Satyr pug
Eupithecia satyrata
Vulnerable Centaurea spp., Galium spp.
Grayling
Hipparchia semele
Vulnerable Festuca ovina, Festuca rubra
Bedstraw hawk-moth
Hyles gallii
Vulnerable Galium spp.
The lackey
Malacosoma neustria
Vulnerable Crataegus monogyna
Pale brindled
Phigalia pilosaria
Vulnerable Crataegus monogyna
Silver studded blue
Plebejus argus
Vulnerable Lotus corniculatus, Ulex spp.
Grizzled skipper
Pyrgus malvae
Vulnerable Potentilla erecta
The anomalous
Stilbia anomala
Vulnerable Molinia caerulea
Early moth
Theria primaria
Vulnerable Crataegus monogyna
Pale eggar
Trichiura crataegi
Vulnerable Crataegus monogyna
Flounced chestnut
Agrochola helvola
Near Threatened Crataegus monogyna
Beaded chestnut
Agrochola lychnidis
Near Threatened Crataegus monogyna
Grey chi
Antitype chi
Near Threatened Crataegus monogyna
Garden tiger
Arctia caja
Near Threatened Sorbus aucuparia
Small pearl-bordered
Boloria selene
Near Threatened Viola riviniana
Small heath
Coenonympha pamphilus
Near Threatened Agrostis spp., Cynosurus cristatus, Festuca spp.
Silver barred
Deltote bankiana
Near Threatened Molinia caerulea
Large thorn
Ennomos autumnaria
Near Threatened Crataegus spp.
The Silurian
Eriopygodes imbecilla
Near Threatened Galium saxatile
Autumnal rustic
Eugnorisma glareosa
Near Threatened Festuca ovina, Galium spp.
Grey pug
Eupithecia subfuscata
Near Threatened Centaurea spp., Crataegus monogyna, Pimpinella saxifraga
Double dart
Graphiphora augur
Near Threatened Crataegus 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.
Rosy minor
Litoligia literosa
Near Threatened Festuca ovina
Swallowtail papilio
Papilio machaon
Near Threatened Pimpinella saxifraga
Red carpet
Xanthorhoe decoloraria
Near Threatened Alchemilla spp.
Dark-barred twin-spot carpet
Xanthorhoe ferrugata
Near Threatened Galium spp.

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

U4 — Lowland dry acid grassland, Upland acid grassland, Upland calcareous grassland

Festuca ovina-Agrostis capillaris-Galium saxatile grassland

Matches 13 species from the description above: Agrostis capillaris, Campanula rotundifolia, Cynosurus cristatus, Danthonia decumbens, Euphrasia officinalis, Festuca ovina, Festuca rubra, Galium saxatile, Lotus corniculatus, Molinia caerulea, Potentilla erecta, Succisa pratensis, Viola riviniana

Calluna vulgaris, Vaccinium myrtillus, Carex binervis, Carex caryophyllea, Carex echinata, Carex nigra, Carex panicea, Carex pilulifera, Juncus effusus, Juncus squarrosus, Luzula campestris, Luzula multiflora, Luzula sylvatica, Mnium hornum, Dicranum scoparium, Racomitrium lanuginosum, Hylocomium splendens, Hypnum cupressiforme, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Rhytidiadelphus triquetrus, Thuidium tamariscinum, Polytrichastrum alpinum, Polytrichum commune, Lophocolea bidentata, Conopodium majus, Achillea millefolium, Bellis perennis, Cirsium arvense, Cirsium vulgare, Taraxacum officianalis, Campanula rotundifolia, Succisa pratensis, Cerastium fontanum, Lathyrus montanus, Lotus corniculatus, Trifolium pratense, Trifolium repens, Thymus praecox, Euphrasia officinalis, Oxalis acetosella, Plantago lanceolata, Veronica chamaedrys, Veronica officinalis, Polygala serpyllifolia, Rumex acetosa, Primula vulgaris, Anemone nemorosa, Ranunculus acris, Ranunculus repens, Potentilla erecta, Poterium sanguisorba, Galium saxatile, Galium verum, Viola lutea, Viola palustris, Viola riviniana, Agrostis canina, Agrostis capillaris, Alopecurus pratensis, Anthoxanthum odoratum, Avenula pratensis, Briza media, Cynosurus cristatus, Dactylis glomerata, Danthonia decumbens, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Holcus lanatus, Holcus mollis, Lolium perenne, Molinia caerulea, Nardus stricta, Poa annua, Poa pratensis, Blechnum spicant, Pteridium aquilinum, Chara curta

M25 — Blanket bog, Coastal floodplain grazing marsh, Lowland fen, Purple moor grass and rush pasture, Upland acid grassland

Molinia caerulea-Potentilla erecta mire

Matches 10 species from the description above: Agrostis capillaris, Centaurea nigra, Danthonia decumbens, Festuca ovina, Festuca rubra, Juncus acutiflorus, Molinia caerulea, Potentilla erecta, Succisa pratensis, Ulex gallii

Salix cinerea, Calluna vulgaris, Erica tetralix, Myrica gale, Vaccinium oxycoccos, Ulex europaeus, Ulex gallii, Carex echinata, Carex flacca, Carex nigra, Carex panicea, Eriophorum angustifolium, Schoenus nigricans, Juncus acutiflorus, Juncus articulatus, Juncus effusus, Juncus subnodulosus, Luzula campestris, Luzula multiflora, Aulacomnium palustre, Pohlia nutans, Calliergon giganteum, Calliergonell cuspidatum, Hypnum jutlandicum, Kindbergia praelonga, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus squarrosus, Polytrichum commune, Sphagnum auriculatum, Sphagnum capillifolium, Sphagnum fallax, Sphagnum palustre, Sphagnum papillosum, Sphagnum subnitens, Calypogeia fissa, Cephalozia bicuspidata, Lophocolea bidentata, Lophozia ventricosa, Angelica sylvestris, Carum verticillatum, Hydrocotyle vulgaris, Achillea ptarmica, Centaurea nigra, Cirsium palustre, Eupatorium cannabinum, Pulicaria dysenterica, Serratula tinctoria, Cardamine pratensis, Lobelia urens, Succisa pratensis, Valeriana officinalis, Equisetum palustre, Lotus pedunculatus, Hypericum pulchrum, Hypericum tetrapterum, Mentha aquatica, Scutellaria minor, Menyanthes trifoliata, Narthecium ossifragum, Epilobium palustre, Dactylorhiza maculata, Rumex acetosa, Ranunculus acris, Ranunculus flammula, Filipendula ulmaria, Potentilla erecta, Rubus fruticosus agg., Galium palustre, Viola palustris, Agrostis canina, Agrostis capillaris, Agrostis curtisii, Agrostis stolonifera, Anthoxanthum odoratum, Danthonia decumbens, Deschampsia cespitosa, Festuca ovina, Festuca rubra, Holcus lanatus, Molinia caerulea, Nardus stricta, Phragmites australis, Dryopteris carthusiana, Osmunda regalis

U5 — Upland acid grassland, Upland calcareous grassland

Nardus stricta-Galium saxatile grassland

Matches 9 species from the description above: Agrostis capillaris, Campanula rotundifolia, Danthonia decumbens, Festuca ovina, Festuca rubra, Galium saxatile, Molinia caerulea, Potentilla erecta, Viola riviniana

Empetrum nigrum subsp.nigrum, Calluna vulgaris, Erica cinerea, Erica tetralix, Vaccinium myrtillus, Carex bigelowii, Carex binervis, Carex demissa, Carex nigra, Carex panicea, Carex pilulifera, Carex pulicaris, Eriophorum angustifolium, Eriophorum vaginatum, Trichophorum cespitosum, Juncus effusus, Juncus squarrosus, Luzula campestris, Luzula multiflora, Luzula sylvatica, Huperzia selago, Selaginella selaginoides, Aulacomnium palustre, Pohlia nutans, Campylopus flexuosus, Dicranella heteromalla, Dicranum scoparium, Racomitrium lanuginosum, Calliergonell cuspidatum, Hylocomium splendens, Hypnum cupressiforme, Plagiothecium undulatum, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Thuidium tamariscinum, Polytrichastrum alpinum, Polytrichum commune, Polytrichum formosum, Polytrichum juniperinum, Sphagnum papillosum, Barbilophozia floerkei, Calypogeia muelleriana, Diplophyllum albicans, Lophocolea bidentata, Lophozia ventricosa, Pleurozia purpurea, Ptilidium ciliare, Scapania gracilis, Cetraria islandica, Cladonia uncialis, Cirsium palustre, Scorzoneroides autumnalis, Campanula rotundifolia, Cerastium fontanum, Equisetum palustre, Vaccinium vitis-idaea, Trifolium repens, Narthecium ossifragum, Plantago lanceolata, Polygala serpyllifolia, Anemone nemorosa, Ranunculus acris, Alchemilla alpina, Potentilla erecta, Galium saxatile, Viola riviniana, Agrostis capillaris, Agrostis vinealis, Anthoxanthum odoratum, Danthonia decumbens, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Molinia caerulea, Nardus stricta, Blechnum spicant

U3 — Lowland dry acid grassland, Upland acid grassland

Agrostis curtisii grassland

Matches 8 species from the description above: Agrostis capillaris, Danthonia decumbens, Festuca ovina, Festuca rubra, Galium saxatile, Molinia caerulea, Potentilla erecta, Ulex gallii

Calluna vulgaris, Erica cinerea, Erica tetralix, Vaccinium myrtillus, Ulex europaeus, Ulex gallii, Carex binervis, Carex panicea, Carex pilulifera, Luzula campestris, Dicranum scoparium, Hylocomium splendens, Hypnum cupressiforme, Pleurozium schreberi, Pseudoscleropodium purum, Rhytidiadelphus squarrosus, Cladonia floerkeana, Cladonia impexa, Hypochaeris radicata, Teucrium scorodonia, Polygala serpyllifolia, Potentilla erecta, Galium saxatile, Agrostis capillaris, Agrostis curtisii, Agrostis vinealis, Anthoxanthum odoratum, Danthonia decumbens, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Molinia caerulea, Nardus stricta, Pteridium aquilinum

U2 — Brownfield, Lowland dry acid grassland, Upland acid grassland

Deschampsia flexuosa grassland

Matches 6 species from the description above: Agrostis capillaris, Festuca ovina, Festuca rubra, Galium saxatile, Molinia caerulea, Potentilla erecta

Betula pendula, Quercus hybrid, Empetrum nigrum subsp.nigrum, Calluna vulgaris, Vaccinium myrtillus, Ulex europaeus, Carex nigra, Eriophorum vaginatum, Juncus effusus, Juncus squarrosus, Luzula multiflora, Orthodontium lineare, Pohlia nutans, Campylopus pyriformis, Dicranum scoparium, Hypnum cupressiforme, Plagiothecium undulatum, Pleurozium schreberi, Rhytidiadelphus squarrosus, Polytrichum commune, Polytrichum piliferum, Barbilophozia floerkei, Cladonia gracilis, Chamerion angustifolium, Rumex acetosa, Rumex acetosella, Potentilla erecta, Rubus fruticosus agg., Galium saxatile, Agrostis capillaris, Agrostis vinealis, Anthoxanthum odoratum, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Holcus mollis, Molinia caerulea, Nardus stricta, Poa annua, Pteridium aquilinum