Three Dykes
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Condition (Natural England)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| SE804682 | — | Favourable | 0.64 | 2009-07-18 |
Geology & landscape
Geological Period: Jurassic · Rock Type: Limestone
Description
Description Three Dykes comprises a small ancient earthwork of parallel ridges and hollows supporting a species rich Jurassic Limestone grassland flora. The close grazed turf contains sheep's fescue Festuca ovina, crested dog's tail Cynosurus cristatus, crested hair grass Koeleria macrantha, hairy oat Avenula pubescens, quaking grass Briza media and carnation grass Carex flacca. Many lime lving plants (calcicoles) occur, including felwort Gentianella amarella, carline thistle Carlina vulgaris and rock rose Helianthemum nummularium. This is one of few Yorkshire localities for squinancywort Asperula cynanchica, whilst horseshoe vetch Hippocrepis comosa and purple milk vetch Astragalus danicus which occur here are rare in east Yorkshire. * Under Section 23 of the National Parks and Access to the Countryside Act 1949.
Species mentioned
Show the 12 species mentioned in the description, with red-list status| English name search for this in other sites |
Latin name search with Google |
IUCN / Red List | Type | Family |
|---|---|---|---|---|
| downy oat grass | Avenula pubescens | LC | grass | poaceae |
| quaking grass | Briza media | VU | grass | poaceae |
| crested dog's tail | Cynosurus cristatus | LC | grass | poaceae |
| sheep's fescue | Festuca ovina | LC | grass | poaceae |
| crested hair-grass | Koeleria macrantha | NT | grass | poaceae |
| squinancywort | Asperula cynanchica | VU | herb | rubiaceae |
| purple milk vetch | Astragalus danicus | EN | herb | fabaceae |
| carline thistle | Carlina vulgaris | LC | herb | asteraceae |
| autumn gentian | Gentianella amarella | LC | herb | gentianaceae |
| rock roses | Helianthemum nummularium | VU | herb | cistaceae |
| horseshoe vetch | Hippocrepis comosa | VU | herb | fabaceae |
| glaucus sedge | Carex flacca | LC | sedge | cyperaceae |
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.
| Species | Status | Via host-plant |
|---|---|---|
| Least minor Photedes captiuncula |
Endangered | Carex flacca |
| Northern brown Aricia artaxerxes |
Vulnerable | Helianthemum nummularium |
| Dingy skipper Erynnis tages |
Vulnerable | Hippocrepis comosa |
| Satyr pug Eupithecia satyrata |
Vulnerable | Helianthemum nummularium |
| Grayling Hipparchia semele |
Vulnerable | Festuca ovina |
| Silver studded blue Plebejus argus |
Vulnerable | Helianthemum nummularium, Hippocrepis comosa |
| Small heath Coenonympha pamphilus |
Near Threatened | Cynosurus cristatus, Festuca spp. |
| Autumnal rustic Eugnorisma glareosa |
Near Threatened | Festuca ovina |
| Silver-spotted skipper Hesperia comma |
Near Threatened | Festuca ovina |
| Silky wave Idaea dilutaria |
Near Threatened | Helianthemum nummularium |
| Rosy minor Litoligia literosa |
Near Threatened | Carex flacca, Festuca ovina |
| The blackneck Lygephila pastinum |
Near Threatened | Astragalus 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.