Clegir Mawr

Site of Special Scientific Interest · 53.3779, -4.5590

Description

Description This site is designated for its botanical interest. The most noteworthy feature is the presence of a large population of the nationally rare annual rockrose Tuberaria Guttata growing in one of its nine known British localities. This is the only extant site on the main island of Anglesey, seven of the remainder being on Holy Island with one in the Lleyn Peninsula. Tuberaria Guttata is associated with thin acidic soils on rocky ridgelines or steep slopes. The more frequent associated species include sheep's fescue Festuca ovina, common bent Agrostis capillaris, squirrel-tail fescue Vulpia bromoides, early hair-grass Aira praecox, heather Calluna vulgaris, bell heather Erica Cinerea, western gorse Ulex gallii, spring squill Scilla verna and English stonecrop Sedum anglicum. Other notable plant species present include the nationally uncommon golden-samphire Inula Crithmoides on the sea cliffs, and the locally uncommon prickly sedge Carex Muricata subsp. Lamprocarpa and dodder Cuscuta epithymum.

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
early hair grass Aira praecox VU grass poaceae
sheep's fescue Festuca ovina LC grass poaceae
squirrel tail fescue Vulpia bromoides LC grass poaceae
common dodder Cuscuta epithymum LC herb convolvulaceae
spring squill Scilla verna LC herb liliaceae
English stonecrop Sedum anglicum LC herb crassulaceae
western gorse Ulex gallii LC shrub leguminosae
bell heather or ling Calluna vulgaris NT shrub dwarf 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
Shoulder-striped clover
Heliothis maritima
Endangered Calluna vulgaris
Broom moth
Ceramica pisi
Vulnerable Calluna vulgaris
Satyr pug
Eupithecia satyrata
Vulnerable Calluna vulgaris
Grayling
Hipparchia semele
Vulnerable Aira praecox, Festuca ovina
True lover's knot
Lycophotia porphyrea
Vulnerable Calluna vulgaris
Silver studded blue
Plebejus argus
Vulnerable Calluna vulgaris, Ulex spp.
Pale eggar
Trichiura crataegi
Vulnerable Calluna vulgaris
Flounced chestnut
Agrochola helvola
Near Threatened Calluna vulgaris
Small heath
Coenonympha pamphilus
Near Threatened Agrostis spp., Festuca spp.
Grey scalloped
Dyscia fagaria
Near Threatened Calluna vulgaris
Autumnal rustic
Eugnorisma glareosa
Near Threatened Calluna vulgaris, Festuca ovina
Silver-spotted skipper
Hesperia comma
Near Threatened Festuca ovina
Weaver's wave
Idaea contiguaria
Near Threatened Calluna vulgaris
Wall
Lasiommata megera
Near Threatened Agrostis spp.
Rosy minor
Litoligia literosa
Near Threatened Festuca ovina

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.