The following are plant species which are or have been held to be at least nationally extinct in the British Isles, since Britain was cut off from the European continent, including any which have been reintroduced or reestablished, not including regional extirpations. Many of these species persist in other countries.
Adonis annua, pheasant's eye (extinct in Ireland, Scotland and Wales, survives in England)[1]
Agrostemma githago, corncockle (died out in Ireland, reintroduced) persists in all countries of the United Kingdom[1]
Ajuga genevensis, blue bugle (extinct across the whole of the British Isles since 1967)[2]
Anthemis arvensis, corn chamomile (died out in Ireland, reintroduced) persists in all countries of the United Kingdom[1]
Arnoseris minima, lamb-succory (extinct across the British Isles in 1971) one recent sighting in England[3]
Aulacomnium turgidum, swollen thread moss (extinct in England since 1878) persists in Scotland[2]
Bartramia stricta, upright apple-moss (extinct in England since 1864) persists in Wales[2]
Bromus interruptus, interrupted brome (died out in the wild globally in 1970) (reintroduced from stored seed in 2004)[2][4]
Bryum calophyllum, matted bryum (extinct in England since 1983) may persist in Scotland[2]
Bryum turbinatum, topshape thread-moss (extinct across the British Isles since the 1940s)[2]
Carex davalliana, Davall's sedge (extinct across the British Isles since 1852)[3]
Carex trinervis, three-nerved sedge (extinct across the British Isles since 1869)[2]
Caucalis platycarpos, small bur parsley (extinct across the British Isles since the 1950s)[2]
Centaurium scilloides, perennial centaury (died out in England in 1967) possibly persists in Wales and the south of England[2]
Sphagnum obtusum, obtuse bog moss (extinct across the British Isles since 1911)[2]
Sphagnum strictum, pale bog moss (extinct across the British Isles since the 1950s) 2 recent unconfirmed sightings in Scotland[2]
Spiranthes aestivalis, summer lady's-tresses (extinct across the British Isles since the 1950s)[2]
Spiranthes romanzoffiana, Irish lady's tresses (extinct in England since the 1990s) persists in Scotland, Ireland and Northern Ireland, recently spread to Wales[2]
^Bird, S. A.; Esseen, P. J.; Hewitt, R. (July 4, 2017). "Reintroductions of native plant species to the United Kingdom". International Zoo Yearbook. 51 (1): 32–49. doi:10.1111/izy.12156.