The following is a list of native plant and animal species which are found in Britain, but only at a single location.
Key to conservation designations for species:
Key to conservation designations for sites:
| Species | Conservation designation(s) of species | Location at which found | Conservation designation(s) of location | Date of discovery at this location | Formerly found elsewhere |
| Thamnobryum angustifolium, Derbyshire feathermoss | RDB (CR) | Derbyshire | SSSI | 1886 | No |
This section currently lists non-critical species and critical species in the smaller apomictic genera; many microspecies in the apomictic genera Hieracium (hawkweeds), Rubus (brambles) and Taraxacum (dandelions) are also found at just a single site each.
| Species | Conservation designation(s) of species | Location at which found | Conservation designation(s) of location | Date of discovery at this location | Formerly found elsewhere | |
| Diapensia Diapensia lapponica | RDB (vu), W&CA 8 | Glenfinnan | None | 1951 | No | |
| Rannoch-rush Scheuchzeria palustris | RDB (vu) | Rannoch Moor | SSSI, NNR | 1910 | Yes | |
| Least adder's-tongue Ophioglossum lusitanicum | RDB (vu) | St Agnes, Isles of Scilly | SSSI | 1950 | No | |
| Lundy cabbage Coincya wrightii | RDB (vu), W&CA 8 | Lundy, Devon | No | |||
| Alpine rock-cress Arabis alpina | RDB (vu) | Isle of Skye | No | |||
| Bristol rock-cress Arabis scabra | RDB (vu), W&CA 8 | Avon Gorge, Bristol | No | |||
| Lady's-slipper Cypripedium calceolus | RDB (cr), W&CA 8 | Wharfedale | Yes | |||
| Shetland mouse-ear Cerastium nigrescens | RDB (vu) | Unst, Shetland | 1837 | No | ||
| Teesdale sandwort Minuartia stricta | Widdybank Fell, Teesdale | No | ||||
| Wild cotoneaster Cotoneaster cambricus | Great Orme Head | No | ||||
| Arran whitebeam Sorbus arranensis | Isle of Arran | No | ||||
| Arran service-tree Sorbus pseudofennica | Isle of Arran | No | ||||
| Catacol whitebeam Sorbus pseudomeinichii | Isle of Arran | No | ||||
| Wilmott's whitebeam Sorbus willmottiana | Avon Gorge | No | ||||
| Bristol whitebeam Sorbus bristoliensis | Avon Gorge | No | ||||
| The sea-lavender Limonium paradoxum | St David's Head, Pembrokeshire | No | ||||
| The sea-lavender Limonium transwallianum | Giltar Point, Pembrokeshire | No | ||||
| The sea-lavender Limonium loganicum | Logan Rock to Carn Les Boel, Cornwall | No | ||||
| The eyebright Euphrasia campbelliae | Isle of Lewis | No | ||||
| Wall germander Teucrium chamaedrys | Beachy Head, Sussex | No | ||||
| Leafless hawk's-beard Crepis praemorsa | Cumbria | No | ||||
| Wood calamint Clinopodium menthifolium | Isle of Wight | No | ||||
| Radnor lily Gagea bohemica | Radnorshire | No | ||||
| Sand crocus Romulea columnae | Dawlish Warren | No | ||||
| Strapwort Corrigiola litoralis | Slapton Ley, Devon | Yes | ||||
| Creeping marshwort Apium repens | Port Meadow, Oxford | Yes | ||||
| Fen ragwort Senecio paludosus | Ely | Yes | ||||
| Holly-leaved Naiad Najas marina[1] | RDB (vu) | Norfolk Broads | 1883 | Yes (fossil record) | ||
| Triangular club-rush Scirpus triqueter | Tamar Estuary, Devon | Yes |
| Species | Conservation designation(s) of species | Location at which found | Conservation designation(s) of location | Date of discovery at this location | Formerly found elsewhere | |
| Geotomus punctulatus – a shield bug[2] | RDB1 | Whitesand Bay, Sennen, Cornwall | none | 1864[3] | Yes | |
| Syncopacma suecicella – a micro moth | Kynance Cove, Cornwall | SSSI | 1984[4] | No | ||
| Common forest looper (Pseudocoremia suavis) | Great Work, near Tregonning Hill, Breage, Cornwall | none | 2007[5] | No | ||
| Fisher’s estuarine moth (Gortyna borelii lunata) | Hamford Water, northeast Essex | SSSI | ||||
| Morris's wainscot (Chortodes morrisii morrisii) | west Dorset coast | SSSI | ||||
| Sphaerius acaroides – a sphaeriusid beetle | Eype Mouth, Dorset | No | ||||
| Sitona gemellatus – a weevil | Eype Mouth, Dorset | Yes | ||||
| Prostoma jenningsi – a ribbon worm[6] [7] | A lake between Croston and Bretherton, Lancashire | 1967 | No | |||
| Trembling sea mat (Victorella pavida)[8] | Schedule 5 of the Wildlife and Countryside Act 1981 and Species Action Plan | Swanpool, Falmouth | SSSI and LNR | 1968 | Yes | |
| Megathiris detruncata – a lamp shell[9] [10] | 35 fathom mark off Men-a-vaur, Isles of Scilly | 1888 | No | |||
| Ivell's sea anemone (Edwardsia ivelli) | Schedule 5 of the Wildlife and Countryside Act 1981 | Widewater Lagoon, West Sussex | 1975 | No |
| Species | Conservation designation(s) of species | Location at which found | Conservation designation(s) of location | Date of discovery at this location | Formerly found elsewhere | |
| Common crane (Grus grus) (see note 1) | RDB | The Norfolk Broads | 1979 | Yes |
. Red Data Book for Cornwall and the Isles of Scilly. 2009. Croceago Press. Praze-an-Beeble. 978-1-901685-01-5. Alexander, Keith. 2nd. Hemiptera. In CISFBR. 217.
. Red Data Book for Cornwall and the Isles of Scilly. 2009. Croceago Press. Praze-an-Beeble. 978-1-901685-01-5. 525–8. Gainey Paul. 2nd. Bryozoa (Polyzoa, Ectoprocta). In CISFBR.
. Red Data Book for Cornwall and the Isles of Scilly. 2009. Croceago Press. Praze-an-Beeble. 978-1-901685-01-5. Turk, Stella. 2nd. Lamp Shells (Brachiopoda). In CISFBR. 524.