| Carex remota | GB, VC73 Kirkcudbrightshire, Galloway | M Hildred Bigwood | | 7/1972 | ABS |
| Carex sylvatica | GB, VC46 Cardiganshire, Clettwr Valley | M Hildred Bigwood | | 7/1972 | ABS |
| Carex viridula subsp. brachyrrhyncha | GB, VC88 Mid Perthshire, Ben Lawers | M Hildred Bigwood | | 12/6/1965 | ABS |
| Carex viridula subsp. brachyrrhyncha | GB, VC88 Mid Perthshire, Ben Lawers | M Hildred Bigwood | | 13/6/1965 | ABS |
| Carex viridula subsp. brachyrrhyncha | GB, VC105 West Ross & Cromarty, Enard Bay | M Hildred Bigwood | | 24/6/1965 | ABS |
| Carex viridula subsp. brachyrrhyncha | GB, VC108 West Sutherland, Inchnadamph | M Hildred Bigwood | | 23/6/1965 | ABS |
| Carex viridula subsp. oedocarpa | GB, VC107 East Sutherland, River Fleet | M Hildred Bigwood | | 16/7/1968 | ABS |
| Carex viridula subsp. oedocarpa | GB, VC108 West Sutherland, Altnaharra | M Hildred Bigwood | | 12/7/1968 | ABS |
| Carum verticillatum | GB, VC42 Breconshire, River Tywi | M Hildred Bigwood | | 13/8/1968 | ABS |
| Catapodium marinum | GB, VC41 Glamorganshire, Swansea,Llangennith Burrows | M Hildred Bigwood | | 5/1967 | ABS |
| Centaurium scilloides | GB, VC45 Pembrokeshire, Newport | M Hildred Bigwood | | 1/8/1967 | ABS |
| Cerastium fontanum | GB, VC46 Cardiganshire, Ynyslas Dunes | M Hildred Bigwood | | 7/1972 | ABS |
| Cerastium fontanum | GB, VC46 Cardiganshire, Ynyslas Dunes | M Hildred Bigwood | | 7/1972 | ABS |
| Ceratocapnos claviculata | GB, VC46 Cardiganshire, Llanbadarn | M Hildred Bigwood | | 25/5/1978 | ABS |
| Chamerion angustifolium | GB, VC46 Cardiganshire, Borth Bog | M Hildred Bigwood | | 7/1972 | ABS |
| Chamerion angustifolium | GB, VC46 Cardiganshire, Borth Bog | M Hildred Bigwood | | 7/1972 | ABS |
| Cicendia filiformis | GB, VC45 Pembrokeshire, Goodwick | M Hildred Bigwood | | 1/8/1967 | ABS |
| Cicerbita macrophylla | IE, VCH9 Co. Clare, Ballyvaughan | M Hildred Bigwood | | 16/7/1969 | ABS |
| Cicerbita macrophylla | IE, VCH9 Co. Clare, Ballyvaughan | M Hildred Bigwood | | 16/7/1969 | ABS |
| Circaea lutetiana | GB, VC46 Cardiganshire, LLanfarian, Nant Lolwyn | M Hildred Bigwood | | 8/1972 | ABS |
| Circaea lutetiana | GB, VC46 Cardiganshire, LLanfarian, Nant Lolwyn | M Hildred Bigwood | | 8/1972 | ABS |
| Circaea lutetiana x alpina = C. x intermedia | GB, VC42 Breconshire, Fannog | M Hildred Bigwood | | 8/1968 | ABS |
| Circaea lutetiana x alpina = C. x intermedia | GB, VC46 Cardiganshire, River Towy | M Hildred Bigwood | | 8/1968 | ABS |
| Cirsium heterophyllum | GB, VC96 East Inverness-shire, Newtonmore | M Hildred Bigwood | | 16/6/1975 | ABS |
| Clinopodium calamintha | GB, VC26 West Suffolk, Kersey | M Hildred Bigwood | | 9/1971 | ABS |
| Cochlearia danica | GB, VC46 Cardiganshire, Aberystwyth | M Hildred Bigwood | | 6/1967 | ABS |
| Cochlearia danica | GB, VC46 Cardiganshire, Aberystwyth | M Hildred Bigwood | | 4/1967 | ABS |
| Cochlearia officinalis | GB, VC46 Cardiganshire, Tanybwlch | M Hildred Bigwood | | 4/1967 | ABS |
| Cochlearia officinalis | GB, VC46 Cardiganshire, Tanybwlch | M Hildred Bigwood | | 6/1967 | ABS |
| Cochlearia pyrenaica subsp. pyrenaica | GB, VC66 County Durham, Allendale Moor | M Hildred Bigwood | | 26/7/1975 | ABS |
| Conium maculatum | GB, VC46 Cardiganshire, Aberystwyth | M Hildred Bigwood | | 8/1978 | ABS |
| Conopodium majus | GB, VC46 Cardiganshire, Llanbadarn | M Hildred Bigwood | | 25/5/1978 | ABS |
| Conyza canadensis | GB, VC39 Staffordshire, Himley | M Hildred Bigwood | | 9/1969 | ABS |
| Coronopus didymus | GB, VC46 Cardiganshire, Aberystwyth | M Hildred Bigwood | | 7/1973 | ABS |
| Crepis capillaris | GB, VC45 Pembrokeshire, Stackpole Quay | M Hildred Bigwood | | 27/8/1967 | ABS |
| Crepis nicaeensis | GB, VC46 Cardiganshire, Llanfihangel-y-creuddyn | M Hildred Bigwood | | 7/1967 | ABS |
| Cynosurus cristatus | GB, VC46 Cardiganshire, Llanfihangel-y-creuddyn | M Hildred Bigwood | | 7/1973 | ABS |
| Cystopteris fragilis | IE, Ambiguous locality (IE), Burren | M Hildred Bigwood | | 24/3/1972 | ABS |
| Dactylis glomerata | GB, VC46 Cardiganshire, Llanfihangel-y-creuddyn | M Hildred Bigwood | | 6/1973 | ABS |
| Dactylis glomerata | GB, VC46 Cardiganshire, Llanfihangel-y-creuddyn | M Hildred Bigwood | | 6/1973 | ABS |