| Agrostis stolonifera | GB, VC54 North Lincolnshire, Cleethorpes | Eric Frederic Drabble Hilda Lake Drabble | Watson Botanical Exchange Club Augustin Ley Eric Frederic Drabble Hilda Lake Drabble | 7/1909 | BIRM |
| Agrostis stolonifera x Polypogon monspeliensis = x Agropogon littoralis | GB, VC16 West Kent, Allhallows | Job Edward Lousley | Watson Botanical Exchange Club Harold Stuart Thompson | 2/7/1933 | BIRM |
| Aira caryophyllea var. multiculmis | GB, VC113 Channel Islands, Saint Aubin's | James Walter White | Watson Botanical Exchange Club Harold Stuart Thompson | 8/6/1897 | BIRM |
| Ajuga chamaepitys | GB, VC30,VC20, Tingley Wood | Joseph Edward Little | Watson Botanical Exchange Club | 7/1909 6/1929 | SLBI |
| Ajuga chamaepitys | GB, VC17 Surrey, Box Hill | Edward Cleminshaw | Watson Botanical Exchange Club Edward Cleminshaw | 7/1905 | K |
| Ajuga chamaepitys | GB, VC17 Surrey, Chipstead | Job Edward Lousley | Watson Botanical Exchange Club Isaac A Helsby | 23/6/1923 | SLBI |
| Ajuga chamaepitys | GB, VC17 Surrey, Reigate Hill | Charles Edgar Salmon | Watson Botanical Exchange Club Charles Edgar Salmon Harold Stuart Thompson | 20/6/1899 | BIRM |
+ | Ajuga chamaepitys | GB, VC20 Hertfordshire, Hitchin,Wilbury Hill | Joseph Edward Little | Watson Botanical Exchange Club George Claridge Druce Mary Hayward | 22/8/1912 | MANCH |
| Ajuga chamaepitys | GB, VC20 Hertfordshire, TIngley Wood | Joseph Edward Little | Watson Botanical Exchange Club | 6/1929 to 7/1929 | K |
| Ajuga chamaepitys | GB, VC20 Hertfordshire, Tingley Wood Plantation | Joseph Edward Little | Watson Botanical Exchange Club J Fraser | 6/1929 to 7/1929 | K |
| Ajuga chamaepitys | GB, VC30 Bedfordshire, Barton Hills | Dorcas Martha Higgins | Watson Botanical Exchange Club Augustin Ley | 2/8/1906 | BIRM |
| Ajuga pyramidalis | GB, VC109 Caithness, Berriedale | | Watson Botanical Exchange Club Augustin Ley William Richardson Linton | 21/7/1888 | BIRM |
| Ajuga reptans | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 16/5/1920 | BIRM |
| Alchemilla acutiloba | GB, VC20 Hertfordshire, Hitchin Cultivated GB, VC94 Banffshire, River Fiddich | Joseph Edward Little Katherine D Little | Watson Botanical Exchange Club | 1928 23/9/1929 9/6/1930 | SLBI |
| Alchemilla glabra | GB, VC14 East Sussex, Crowborough | H M Salmon | Watson Botanical Exchange Club Charles Edgar Salmon | 6/1912 | SLBI |
| Alchemilla glabra | GB, VC14 East Sussex, Lindfield Cultivated | Richard Spiers Standen | Watson Botanical Exchange Club Augustin Ley Richard Spiers Standen | 30/5/1909 | BIRM |
| Alchemilla glabra | GB, VC39 Staffordshire, Morridge Side | Albert Bruce Jackson T E Routh | Watson Botanical Exchange Club T E Routh William Robert Sherrin | 23/6/1908 | SLBI |
| Alchemilla glabra | GB, VC48 Merionethshire, Arthog | William Charles Barton | Watson Botanical Exchange Club Harold Stuart Thompson William Charles Barton | 16/6/1915 | BIRM |
| Alchemilla glabra | GB, VC65 North-west Yorkshire, Jervaulx Abbey | Joseph Edward Little | Watson Botanical Exchange Club | 1/6/1925 | SLBI |
| Alchemilla monticola | GB, VC66 County Durham, Teesdale Cultivated | Alfred James Wilmott | Watson Botanical Exchange Club Charles Edgar Salmon Harold Stuart Thompson | 20/5/1926 | BIRM |
| Alchemilla monticola | GB, VC17 Surrey, Reigate Cultivated GB, VC66 County Durham, Teesdale | Alfred James Wilmott Charles Edgar Salmon | Charles Edgar Salmon Job Edward Lousley Watson Botanical Exchange Club | 20/5/1926 | SLBI |
| Alchemilla monticola | GB, VC66 County Durham, Teesdale Cultivated | Alfred James Wilmott | Watson Botanical Exchange Club Charles Edgar Salmon | 20/5/1926 | SLBI |
| Alchemilla pratensis | GB, VC20 Hertfordshire, Hitchin Cultivated GB, VC94 Banffshire, River Fiddich | Joseph Edward Little Katherine D Little | Watson Botanical Exchange Club | 1928 23/9/1929 9/6/1930 | SLBI |
| Alchemilla vulgaris | GB, VC17 Surrey, Reigate Cultivated | Charles Edgar Salmon | Watson Botanical Exchange Club | 5/1928 | SLBI |
| Alchemilla vulgaris subsp. alpestris | GB, VC69 Westmorland, Grisedale Pass | Albert John Crosfield | Watson Botanical Exchange Club Albert John Crosfield | 8/9/1897 | SHYB |
| Alchemilla xanthochlora | GB, VC20 Hertfordshire, Hitchin Cultivated | Katherine D Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 23/9/1929 | BIRM |
| Alchemilla xanthochlora | GB, VC48 Merionethshire, Dolgellau | William Charles Barton | Watson Botanical Exchange Club Harold Stuart Thompson William Charles Barton | 15/8/1923 | BIRM |
| Alisma lanceolatum | GB, VC17 Surrey, Woking | W Biddiscombe | Watson Botanical Exchange Club W Biddiscombe | 8/1924 | SLBI |
| Alisma lanceolatum | GB, VC29 Cambridgeshire, Burwell | Albert John Crosfield | Watson Botanical Exchange Club Albert John Crosfield | 8/9/1914 | SLBI |
| Alisma lanceolatum | GB, VC29 Cambridgeshire, Burwell Lode | Albert John Crosfield | Watson Botanical Exchange Club William Robert Sherrin Albert John Crosfield | 14/9/1909 | SLBI |
| Alisma plantago-aquatica | GB, VC6 North Somerset, Portbury | Harold Stuart Thompson | Watson Botanical Exchange Club Harold Stuart Thompson | 6/5/1922 | SLBI |
| Alisma plantago-aquatica | GB, VC45 Pembrokeshire, Dowrog Common | Edward Francis Linton | Watson Botanical Exchange Club Harold Stuart Thompson | 24/8/1905 | BIRM |
| Allium carinatum | GB, VC17 Surrey, Croydon Cultivated GB, VC17 Surrey, Witley | Arthur Bennett | Watson Botanical Exchange Club | 8/1919 | SLBI |
| Allium carinatum | GB, VC17 Surrey, Witley Cultivated | Arthur Bennett | Watson Botanical Exchange Club | 8/1919 | SLBI |
| Allium carinatum | GB, VC17 Surrey, Witley Cultivated | | Harold Stuart Thompson Watson Botanical Exchange Club Arthur Bennett | 8/1919 | BIRM |
| Allium carinatum | GB, VC83 Midlothian, Carlowrie | McTaggert Cowan | Watson Botanical Exchange Club Harold Stuart Thompson McTaggert Cowan | 12/8/1910 | BIRM |
| Allium carinatum | GB, VC84 West Lothian, Kirkliston, Carlowrie | McTaggert Cowan | Watson Botanical Exchange Club McTaggert Cowan | 12/8/1910 | SLBI |
| Allium carinatum | GB, Perthshire, Tayside | George Claridge Druce | Watson Botanical Exchange Club Patrick Martin Hall Richard Barker Ullman | 8/1918 | SLBI |
| Allium oleraceum | GB, VC63 South-west Yorkshire, Sprotbrough | Coslett Herbert Waddell | Watson Botanical Exchange Club Coslett Herbert Waddell Harold Stuart Thompson | 7/1901 | BIRM |
| Allium schoenoprasum | GB, VC1 West Cornwall, Lizard | Francis José | Watson Botanical Exchange Club Job Edward Lousley | 9/6/1905 | SLBI |