| Anagallis arvensis | GB, VC48 Merionethshire, Barmouth | William Charles Barton | Watson Botanical Exchange Club Harold Stuart Thompson William Charles Barton | 30/7/1915 | BIRM |
| Anagallis arvensis | GB, VC52 Anglesey, Newborough Warren | Ida Mary Roper | Watson Botanical Exchange Club Ida Mary Roper | 28/8/1931 | SLBI |
| Anagallis arvensis subsp. foemina | GB, VC6 North Somerset, Kingweston | Edward Shearburn Marshall | Watson Botanical Exchange Club Edward Shearburn Marshall William Robert Sherrin | 19/8/1915 | SLBI |
| Anagallis minima | GB, VC17 Surrey, Reigate Heath | Albert John Crosfield | Watson Botanical Exchange Club Harold Stuart Thompson | 1/8/1900 | BIRM |
+ | Anagallis minima | GB, VC22 Berkshire, Wokingham,Finchampstead | Eleonora Armitage | Watson Botanical Exchange Club Charles Bailey A Hosking | 10/1903 | MANCH |
| Anaphalis margaritacea | GB, VC34 West Gloucestershire, Woodchester | Henry Peter Reader | Watson Botanical Exchange Club William Hunt Painter | 8/1891 | ABS |
| Anchusa officinalis | GB, VC34 West Gloucestershire, Bristol | James Walter White | Watson Botanical Exchange Club Charles Baylis Green James Walter White | 14/6/1905 | SLBI |
| Anchusa officinalis | GB, VC36 Herefordshire, Ledbury | Spencer Henry Bickham | Watson Botanical Exchange Club Harold Stuart Thompson Spencer Henry Bickham | 19/6/1916 | BIRM |
| Anchusa officinalis | GB, VC48 Merionethshire, Barmouth | William Charles Barton | Watson Botanical Exchange Club Harold Stuart Thompson William Charles Barton | 16/8/1915 | BIRM |
| Andromeda polifolia | GB, VC63 South-west Yorkshire, Goole moor | Charles Waterfall | Watson Botanical Exchange Club Charles Waterfall Charles Edgar Salmon | 6/1896 | ABS |
| Anemone apennina | GB, VC3 South Devon, Dartmouth | S Imeson | The South London Botanical Institute Watson Botanical Exchange Club Harold Stuart Thompson | 5/3/1915 | BIRM |
| Anemone nemorosa | GB, VC1 West Cornwall, Ponsanooth | Ida Mary Roper | Watson Botanical Exchange Club Ida Mary Roper | 7/5/1931 | SLBI |
| Anemone nemorosa var. caerulea | GB, VC34 West Gloucestershire, Lansdown Hill | Harold Stuart Thompson Herbert William Pugsley | Watson Botanical Exchange Club Harold Stuart Thompson | 24/4/1923 | SLBI |
| Angelica archangelica | GB, VC6 North Somerset, University College Garden, Bristol Cultivated | James Walter White | Watson Botanical Exchange Club Augustin Ley | 7/1909 | BIRM |
| Anisantha diandra | GB, VC113 Channel Islands, Jersey, Quennevais | David Thomson Playfair | Watson Botanical Exchange Club David Thomson Playfair | 26/5/1897 | BIRM |
| Anisantha madritensis | GB, VC113 Channel Islands, Guernsey | Robert Hugh Bunting | Augustin Ley William Robert Sherrin Watson Botanical Exchange Club | 7/1909 | BIRM |
| Anisantha madritensis | GB, VC113 Channel Islands, L'Eree, Guernsey | Job Edward Lousley N A McCrea | Watson Botanical Exchange Club Job Edward Lousley | 15/6/1926 | BIRM |
| Anisantha sterilis | GB, VC16 West Kent, Erith | St John Marriott | Watson Botanical Exchange Club Harold Stuart Thompson St John Marriott | 6/1926 | BIRM |
| Anisantha tectorum | GB, VC6 North Somerset, Brislington | | Watson Botanical Exchange Club Ida Mary Roper | 21/5/1915 | BIRM |
| Anisantha tectorum | GB, VC55 Leicestershire, Leicester | W A Vice | Watson Botanical Exchange Club | 9/6/1903 | BIRM |
| Anogramma leptophylla | GB, VC113 Channel Islands, Jersey | Fred G Piquet | Watson Botanical Exchange Club David Thomson Playfair Harold Stuart Thompson | 4/1898 | BIRM |
| Antennaria dioica | GB, VC112 Shetland, Balta Sound | John Wilson Rimington | Watson Botanical Exchange Club Spencer Henry Bickham | 24/6/1891 | SLBI |
| Anthemis arvensis | GB, VC17 Surrey, Ashtead, Thirty Acre Barn | Edward Charles Wallace | Watson Botanical Exchange Club Edward Charles Wallace | 12/6/1929 | SLBI |
| Anthemis arvensis | GB, VC17 Surrey, Ashtead, Thirty Acre Barn | Edward Charles Wallace | Watson Botanical Exchange Club Edward Charles Wallace Harold Stuart Thompson | 12/6/1929 | BIRM |
| Anthemis tinctoria | GB, VC17 Surrey, Godalming | Edward Charles Wallace | Watson Botanical Exchange Club Edward Charles Wallace Harold Stuart Thompson | 16/7/1932 | BIRM |
| Anthoxanthum aristatum subsp. puelii | GB, VC20 Hertfordshire, Hitchin | H C Littlebury | Watson Botanical Exchange Club H C Littlebury Harold Stuart Thompson | 5/6/1915 | BIRM |
| Anthoxanthum aristatum subsp. puelii | GB, VC37 Worcestershire, Malvern | Charles Waterfall | Edward Shearburn Marshall Harold Stuart Thompson Watson Botanical Exchange Club Richard Francis Towndrow | 7/1898 | BIRM |
| Anthoxanthum odoratum | GB, VC34 West Gloucestershire, Bristol | Ida Mary Roper | Watson Botanical Exchange Club Harold Stuart Thompson Ida Mary Roper | 22/5/1919 | BIRM |
| Anthoxanthum odoratum | GB, VC113 Channel Islands, Saint Aubin's | William Charles Barton | Watson Botanical Exchange Club Harold Stuart Thompson William Charles Barton | 18/6/1923 | BIRM |
| Anthriscus cerefolium | GB, VC6 North Somerset, Banwell | Eliza Standerwick Gregory | Watson Botanical Exchange Club Eliza Standerwick Gregory Harold Stuart Thompson | 27/5/1904 | BIRM |
| Anthriscus cerefolium | GB, VC36 Herefordshire, Ross | Eleonora Armitage | Watson Botanical Exchange Club William Robert Sherrin Edward Shearburn Marshall | 12/6/1913 | SLBI |
| Anthriscus sylvestris | GB, VC55 Leicestershire, Whissendine | Arthur Reginald Horwood | Watson Botanical Exchange Club Harold Stuart Thompson | 16/4/1916 | BIRM |
| Anthyllis vulneraria var. coccinea | GB, VC1 West Cornwall, Kynance | Job Edward Lousley | Watson Botanical Exchange Club | 25/5/1929 | SLBI |
| Anthyllis vulneraria var. coccinea | GB, VC1 West Cornwall, Lizard | Job Edward Lousley | Watson Botanical Exchange Club | 24/5/1928 | SLBI |
| Anthyllis vulneraria | GB, VC1 West Cornwall, Newquay | William Charles Barton | Watson Botanical Exchange Club Harold Stuart Thompson William Charles Barton | 5/6/1919 | BIRM |
| Anthyllis vulneraria var. coccinea | GB, VC1 West Cornwall, Newquay | Harold Stuart Thompson | Watson Botanical Exchange Club Harold Stuart Thompson | 6/1925 | SLBI |
| Anthyllis vulneraria | GB, VC1 West Cornwall, Newquay | Harold Stuart Thompson | Watson Botanical Exchange Club | 6/1925 | SLBI |
| Anthyllis vulneraria var. dillenii | GB, VC2 East Cornwall, Bude | Charles Clayton Mountfort | Watson Botanical Exchange Club Augustin Ley E Spearing | 10/6/1908 | BIRM |
| Anthyllis vulneraria | GB, VC2 East Cornwall, Bude | Charles Clayton Mountfort | Watson Botanical Exchange Club E Spearing William Robert Sherrin | 10/6/1908 | SLBI |
| Anthyllis vulneraria | GB, VC6 North Somerset, Shipham | Harold Stuart Thompson | Watson Botanical Exchange Club Harold Stuart Thompson | 27/7/1933 | SLBI |