+ | Herniaria ciliolata | GB, VC113 Channel Islands | Charles Cardale Babington | John Hutton Balfour | | PTH |
| Hieracium strictiforme | GB, Mid-West Perthshire, Glen Falloch | Charles Cardale Babington William Williamson Newbould | Frederick Townsend | 5/8/1846 | SLBI |
| Hierochloe odorata | GB, VC109 Caithness, Thurso | Charles Cardale Babington | George Stephen West | | BIRM |
+ | Hirschfeldia incana | GB, VC113 Channel Islands | Charles Cardale Babington | John Hutton Balfour | 7/1838 | PTH |
+ | Hirschfeldia incana | GB, VC113 Channel Islands | Charles Cardale Babington | John Hutton Balfour | 7/1838 | PTH |
| Hirschfeldia incana | GB, VC113 Channel Islands, Jersey, Quennevais | Charles Cardale Babington | George Stephen West | 9/8/1837 | BIRM |
| Hordelymus europaeus | GB, VC34 West Gloucestershire, Stinchcombe Hill | Charles Cardale Babington | William Hillhouse | 7/10/1854 | BIRM |
| Hymenophyllum wilsonii | GB, VC49 Caernarvonshire, Llanberis | Charles Cardale Babington | George Stephen West William West | 9/9/1866 | BIRM |
+ | Hypericum linariifolium | GB, VC113 Channel Islands, Jersey, Saint Catherine's Bay | Charles Cardale Babington | | 1837 | MANCH |
| Hypericum linariifolium | GB, VC113 Channel Islands, Jersey, Saint Catherine's Bay | | Allan Octavian Hume Charles Cardale Babington Frederick Townsend | 7/1837 | SLBI |
+ | Hypericum maculatum | GB, VC46 Cardiganshire, Aberystwyth | Charles Cardale Babington | John Hutton Balfour | 30/8/1848 | PTH |
+ | Hypochaeris glabra | GB, VC113 Channel Islands | Charles Cardale Babington | John Hutton Balfour | 1828 | PTH |
| Hypochaeris maculata | GB, VC29 Cambridgeshire, Devil's Ditch | Charles Cardale Babington | Charles Cardale Babington George Stephen West | 28/6/1855 | BIRM |
+ | Isoetes histrix | GB, VC113 Channel Islands, Guernsey,Moulin Huet Bay | Charles Cardale Babington | Warrington Museum William Wilson | | MANCH |
| Isolepis cernua | GB, VC52 Anglesey, Llyn Maelog | | Charles Cardale Babington George Stephen West | | BIRM |
| Isolepis cernua | IE, VCH16,VCH27, Leenane | Charles Cardale Babington | John Stevens Henslow | 25/8/1835 | BIRM |
| Isolepis cernua | IE, VCH16 West Galway, Roundstone | | Charles Cardale Babington William Hillhouse | 9/9/1873 | BIRM |
| Isolepis setacea | FR, Vosges, Bitche | Leo | Allan Octavian Hume Frederick Townsend Charles Cardale Babington | | SLBI |
| Juncus compressus | GB, VC48 Merionethshire, Barmouth | Charles Cardale Babington | Frederick Townsend | 1842 | SLBI |
| Juncus trifidus | GB, Ambiguous locality (GB), Clova | William Gardiner | Charles Cardale Babington William Hillhouse | | BIRM |
| Lagurus ovatus | GB, VC113 Channel Islands, Guernsey | | Botanical Society of Edinburgh Charles Cardale Babington | 19/8/1837 | BON |
| Lamium purpureum | GB, VC31 Huntingdonshire, Ramsey | William Richardson Linton | Botanical Exchange Club of The British Isles Charles Cardale Babington William Richardson Linton | 1/5/1886 | ABS |
| Leersia oryzoides | GB, VC13 West Sussex, Amberley | | Charles Cardale Babington George Stephen West | 28/8/1849 | BIRM |
| Leersia oryzoides | GB, VC13 West Sussex, Henfield | | William Hillhouse Charles Cardale Babington | 1847 | BIRM |
| Leersia oryzoides | GB, VC13 West Sussex, Henfield Levels | William Borrer | Charles Cardale Babington George Stephen West | | BIRM |
| Lepidium ruderale | | Charles Cardale Babington | | | SLBI |
+ | Linaria pelisseriana | GB, VC113 Channel Islands | Charles Cardale Babington | John Hutton Balfour | 6/1838 | PTH |
+ | Linaria pelisseriana | GB, VC113 Channel Islands | Charles Cardale Babington | John Hutton Balfour | 1838 | PTH |
| Linaria pelisseriana | GB, VC113 Channel Islands, Jersey | | Joseph Dalton Hooker Charles Cardale Babington | 1867 | K |
| Linaria repens | IE, VCH3,VCH4, Bandon | | William Jackson Hooker Charles Cardale Babington | | K |
| Linaria supina | GB, VC2 East Cornwall, Saint Blazey | George Maw | Charles Cardale Babington George Stephen West George Maw | 6/1849 | BIRM |
| Linaria vulgaris x repens = L. x sepium | IE, VCH3,VCH4, Bandon | George James Allman | Allan Octavian Hume Frederick Townsend Charles Cardale Babington | 8/1852 | SLBI |
| Linaria vulgaris x repens = L. x sepium | IE, Cork | Charles Cardale Babington | Charles Cardale Babington George Stephen West | 8/1852 | BIRM |
| Linnaea borealis | GB, VC95 Moray | | Botanical Society of Edinburgh Charles Cardale Babington William Hillhouse William Alexander Stables | 1834 | BIRM |
+ | Linnaea borealis | GB, VC95 Moray, Moray | Charles Cardale Babington | | 1834 | BIRM |
+ | Linum usitatissimum | GB, VC98 Argyllshire, Crinan | Charles Cardale Babington | John Hutton Balfour | 12/9/1840 | PTH |
| Lolium multiflorum | GB, VC29 Cambridgeshire, Clayhithe | | Charles Cardale Babington William Hillhouse | 1/7/1856 | BIRM |
| Luzula forsteri x pilosa = L. x borreri | GB, VC10 Isle of Wight, Apse Castle Wood | Alexander Goodman More | Charles Cardale Babington George Stephen West | 5/1858 | BIRM |
| Lychnis viscaria | GB, VC89 East Perthshire, Balthayock Den | William Gardiner | Charles Cardale Babington George Stephen West William Gardiner | 6/1848 | BIRM |
| Lysimachia thyrsiflora | GB, VC90 Angus, Rescobie | Charles Cardale Babington | Augustin Ley Charles Cardale Babington | | BIRM |