+ | Orchis anthropophora | | John Thomas Irvine Boswell-Syme | Botanical Society of London Charles Bailey John Thomas Irvine Boswell-Syme | 5/1852 | MANCH |
| Carex ovalis | US, FL, Palm Beach County, Aberdeen | John Thomas Irvine Boswell-Syme | Eric Frederic Drabble Hilda Lake Drabble John Thomas Irvine Boswell-Syme | 8/1851 | BM |
| Thalictrum minus subsp. majus | SE, Uppsala l, Uppsala Cultivated | John Thomas Irvine Boswell-Syme | Botanical Exchange Club of The British Isles Augustin Ley | 9/1879 | BIRM |
| Carex arenaria | IE, Ambiguous locality (IE), Mullaghmore | | John Thomas Irvine Boswell-Syme | 7/1840 | E |
| Carex arenaria | IE, Ambiguous locality (IE), Mullaghmore | | John Thomas Irvine Boswell-Syme | 7/1840 | E |
| Carex canescens | IE, VCH39 Co. Antrim, Lough Neagh | William Mateer | John Thomas Irvine Boswell-Syme Frederick Janson Hanbury | 7/1849 | BM |
| Carex elongata | IE, VCH39 Co. Antrim, Lough Neagh | David Moore | John Thomas Irvine Boswell-Syme | 6/1840 | BM |
| Carex canescens | IE, VCH38 Co. Down, Knockbreda | William Mateer | Frederick Janson Hanbury John Thomas Irvine Boswell-Syme William Mateer | 6/1849 | BM |
+ | Salix aurita x repens x herbacea = S. x grahamii | IE, Donegal, Co. Donegal,Muckish Montain | John Thomas Irvine Boswell-Syme | Charles Bailey | 8/1879 | MANCH |
| Salix aurita x repens x herbacea = S. x grahamii | IE, Donegal Cultivated | John Thomas Irvine Boswell-Syme | Charles Bailey | 7/1881 | MANCH |
| Salix aurita x repens x herbacea = S. x grahamii | IE, Donegal Cultivated | John Thomas Irvine Boswell-Syme | Charles Bailey | 7/1881 | MANCH |
| Salix aurita x repens x herbacea = S. x grahamii | IE, Donegal Cultivated | John Thomas Irvine Boswell-Syme | Charles Bailey | 5/1881 | MANCH |
| Eleogiton fluitans | IE, VCH28 Co. Sligo, Mullaghmore | John Thomas Irvine Boswell-Syme | Botanical Society of London Harold Stuart Thompson Thomas Clark John Thomas Irvine Boswell-Syme | 1846 | BIRM |
| Baldellia ranunculoides | IE, VCH28 Co. Sligo, Cliffony | John Thomas Irvine Boswell-Syme | | 7/1840 | E |
| Carex appropinquata | IE, VCH23 Westmeath, Ladestown | David Moore | Frederick Janson Hanbury John Thomas Irvine Boswell-Syme | 6/1845 | BM |
| Carex appropinquata | IE, VCH23 Westmeath, Ladestown | David Moore | John Thomas Irvine Boswell-Syme Frederick Janson Hanbury | 6/1845 | BM |
| Carex divisa | IE, VCH21 Co. Dublin, River Liffey | Alexander Goodman More | John Thomas Irvine Boswell-Syme Frederick Janson Hanbury | 6/1871 | BM |
| Senecio vulgaris | GB, VC85 Fifeshire, Balmuto Cultivated IE, Cork, Cork | John Thomas Irvine Boswell-Syme | | 5/1878 | SLBI |
| Senecio vulgaris | IE, Cork, Cork Cultivated | John Thomas Irvine Boswell-Syme | Augustin Ley | 5/1878 | BIRM |
| Puccinellia maritima | IE, VCH1 South Kerry, Bawnduff | John Thomas Irvine Boswell-Syme | Botanical Society of Edinburgh | 7/1840 | BON |
| Hymenophyllum tunbrigense | IE, Killarney | John Thomas Irvine Boswell-Syme | Harold Stuart Thompson Thomas Clark | 1848 | BIRM |
| Allium triquetrum | GB, VC113 Channel Islands, Vazon Bay, Guernsey | John Thomas Irvine Boswell-Syme | Botanical Society of London Mantua And Montferrat | 6/1853 | BON |
| Carex distans | GB, VC113 Channel Islands, Vazon Bay, Guernsey | John Thomas Irvine Boswell-Syme | | 6/1853 | BON |
| Carex distans | GB, VC113 Channel Islands, Vazon Bay, Guernsey | John Thomas Irvine Boswell-Syme | Augustin Ley | 6/1854 | BIRM |
| Carex punctata | GB, VC113 Channel Islands, Vazon Bay, Guernsey | John Thomas Irvine Boswell-Syme | | 6/1853 | BON |
| Ranunculus ophioglossifolius | GB, VC113 Channel Islands, Saint Peter's Marsh | John Thomas Irvine Boswell-Syme | | 6/1853 | BIRM |
| Schoenoplectus pungens | GB, VC113 Channel Islands, Saint Ouen's Pond | John Thomas Irvine Boswell-Syme | Thomas Clark | 6/1853 | BIRM |
| Orobanche alba | GB, VC113 Channel Islands, Saint Aubin's | John Thomas Irvine Boswell-Syme | Thomas Clark | 6/1859 | BIRM |
| Orobanche purpurea | GB, VC113 Channel Islands, Saint Aubin's | John Thomas Irvine Boswell-Syme | Martha Maria Atwood | 6/1853 | BIRM |
| Orobanche purpurea | GB, VC113 Channel Islands, Saint Aubin's | John Thomas Irvine Boswell-Syme | Augustin Ley John Thomas Irvine Boswell-Syme | 6/1853 | BIRM |
+ | Allium sphaerocephalon | GB, VC113 Channel Islands, Jersey,Saint Aubin's Bay | John Thomas Irvine Boswell-Syme | Botanical Society of London Charles Bailey John Ray Hardy John Thomas Irvine Boswell-Syme | 6/1853 | MANCH |
+ | Ranunculus ophioglossifolius | GB, VC113 Channel Islands, Jersey,Le Marais | John Thomas Irvine Boswell-Syme | | | MANCH |
| Schoenoplectus pungens | GB, VC113 Channel Islands, Jersey, Saint Ouens Pond | John Thomas Irvine Boswell-Syme | George Stephen West | 2/6/1853 | BIRM |
| Achillea maritima | GB, VC113 Channel Islands, Jersey, Saint Ouen's Bay | John Thomas Irvine Boswell-Syme | Allan Octavian Hume Edward Francis Linton | 6/1853 | SLBI |
| Otanthus maritimus | GB, VC113 Channel Islands, Jersey, Saint Ouen's Bay | John Thomas Irvine Boswell-Syme | Harold Stuart Thompson John Thomas Irvine Boswell-Syme Thomas Clark | 6/1853 | BIRM |
| Armeria plantaginea | GB, VC113 Channel Islands, Jersey, Saint Brelade's Bay | John Thomas Irvine Boswell-Syme | Botanical Society of London Harold Stuart Thompson Thomas Clark John Thomas Irvine Boswell-Syme | 6/1853 | BIRM |
| Petrorhagia prolifera | GB, VC113 Channel Islands, Jersey, Quennevais | John Thomas Irvine Boswell-Syme | Augustin Ley | 1853 | BIRM |
+ | Silene conica | GB, VC113 Channel Islands, Jersey, Quennevais | John Thomas Irvine Boswell-Syme | Botanical Society of London Charles Bailey John Thomas Irvine Boswell-Syme | 6/1853 | MANCH |
| Tuberaria guttata | GB, VC113 Channel Islands, Jersey, Petit Port | John Thomas Irvine Boswell-Syme | Botanical Society of London Harold Stuart Thompson Thomas Clark John Thomas Irvine Boswell-Syme | 6/1853 | BIRM |
+ | Cynodon dactylon | GB, VC113 Channel Islands, Guernsey,Vazon Bay | John Thomas Irvine Boswell-Syme | Botanical Society of London Charles Bailey John Ray Hardy | 6/1853 | MANCH |