Mills Rocks

Site of Special Scientific Interest · 51.1156, 0.0192

Condition (Natural England)

Unfavourable Recovering (1)
UnitFeatureConditionArea (ha)Assessed
TQ414370 Unfavourable Recovering 1.91 2014-02-28

Habitats

Bracken scrub

Geology & landscape

Rock Type: Sandstone

Description

Area, 2.25 ha. 5.5 ac. Description This site contains one of the few outcrops of Tunbridge Wells Sandstone in the county with a community of 'Atlantic' plants. This community is unusual and contains several plants with a restricted distribution. The rock outcrops support a number of rare plants and particularly notable is reed fescue grass Festuca altissima which has only one other southern English locality and occurs sparsely elsewhere in Britain. The hay scented buckler fern Dryopteris aemula also grows on the rocks and the rich bryophyte flora mosses and liverworts includes Odontoschisma denudatum, Cephalozia connivens and Calypogeia integristipula. Woodland around and on the plateau top, is very variable. Pedunculate oak Quercus robur, beech Fagus sylvatica, holly Ilex aquifolium, birch Betula pendula and hazel Corylus avellana are all present above bracken and bramble.

Species mentioned

English name
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Latin name
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IUCN / Red List Type Family
hay-scented fern Dryopteris aemula LC fern dryopteridaceae
wood fescue Festuca altissima Not listed in GB list grass poaceae
forcipated pincerwort Cephalozia connivens LC liverwort jungermanniales
matchstick flapwort Odontoschisma denudatum LC liverwort jungermanniales
Calypogeia integristipula LC moss calypogeiaceae
birch Betula pendula LC tree betulaceae
hazel Corylus avellana LC tree corylaceae
beech Fagus sylvatica LC tree fabiaceae
holly Ilex aquifolium LC tree aquifoliaceae
common oak Quercus robur LC tree fagaceae

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
Oak lutestring
Cymatophorina diluta
Endangered Quercus robur
Scarce vapourer
Orgyia recens
Endangered Betula spp., Corylus avellana, Fagus sylvatica, Quercus spp.
The sprawler
Asteroscopus sphinx
Vulnerable Betula spp., Corylus avellana, Fagus sylvatica, Quercus spp.
Broom moth
Ceramica pisi
Vulnerable Betula spp.
Mottled umber
Erannis defoliaria
Vulnerable Betula spp., Corylus avellana, Fagus sylvatica, Quercus spp.
The lackey
Malacosoma neustria
Vulnerable Betula pendula, Corylus avellana, Quercus spp.
Pale brindled
Phigalia pilosaria
Vulnerable Betula pendula, Corylus avellana, Quercus spp.
Early moth
Theria primaria
Vulnerable Quercus spp.
Pale eggar
Trichiura crataegi
Vulnerable Betula spp., Corylus avellana, Quercus spp.
Oak hook-tip
Watsonalla binaria
Vulnerable Betula pendula, Quercus robur
Flounced chestnut
Agrochola helvola
Near Threatened Betula spp., Quercus spp.
Light crimson underwing
Catocala promissa
Near Threatened Quercus robur
Dark crimson underwing
Catocala sponsa
Near Threatened Quercus robur
Small heath
Coenonympha pamphilus
Near Threatened Festuca spp.
Heart moth
Dicycla oo
Near Threatened Quercus robur
Kentish glory
Endromis versicolora
Near Threatened Betula pendula
Large thorn
Ennomos autumnaria
Near Threatened Betula spp., Corylus avellana, Quercus spp.
September thorn
Ennomos erosaria
Near Threatened Betula spp., Fagus sylvatica, Quercus spp.
Autumnal rustic
Eugnorisma glareosa
Near Threatened Betula spp.
Double dart
Graphiphora augur
Near Threatened Betula spp., Quercus spp.
Clay fan-foot
Paracolax tristalis
Near Threatened Quercus spp.
Common fan-foot
Pechipogo strigilata
Near Threatened Quercus robur
Frosted green
Polyploca ridens
Near Threatened Quercus robur
White prominent
Leucodonta bicoloria
Regionally Extinct Betula 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

W25 — Bracken scrub

Pteridium aquilinum-Rubus fruticosus underscrub

Matches 2 species from the description above: Fagus sylvatica, Quercus robur

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