| Petroselinum segetum | GB, VC16 West Kent, Northfleet | John Thomas Irvine Boswell-Syme | Augustin Ley | 8/1866 | BIRM |
| Agrostis stolonifera x Polypogon monspeliensis = x Agropogon littoralis | GB, VC16 West Kent, Plumstead | John Thomas Irvine Boswell-Syme | Botanical Society of London George Stephen West John Thomas Irvine Boswell-Syme | 6/1852 | BIRM |
| Polypogon monspeliensis | GB, VC16 West Kent, Plumstead | John Thomas Irvine Boswell-Syme | George Stephen West | 6/1852 | BIRM |
| Alopecurus aequalis | GB, VC16 West Kent, Plumstead | John Gilbert Baker John Thomas Irvine Boswell-Syme | George Stephen West | 8/1852 | BIRM |
| Polypogon monspeliensis | GB, VC16 West Kent, Plumstead | John Thomas Irvine Boswell-Syme | Augustin Ley | 7/1853 | BIRM |
| Rumex palustris | GB, VC17 Surrey, Battersea | John Thomas Irvine Boswell-Syme | Botanical Society of London Donor Unknown John Thomas Irvine Boswell-Syme | 8/1850 | BIRM |
| Chenopodium ficifolium | GB, VC17 Surrey, Battersea | John Thomas Irvine Boswell-Syme | Botanical Society of London John Thomas Irvine Boswell-Syme | 8/1854 | BIRM |
| Rumex crispus x obtusifolius = R. x pratensis | GB, VC17 Surrey, East Molesey | John Thomas Irvine Boswell-Syme | Botanical Society of London Donor Unknown | 7/1852 | BIRM |
| Chenopodium vulvaria | GB, VC17 Surrey, East Molesey | John Thomas Irvine Boswell-Syme | Botanical Society of London George Stephen West John Thomas Irvine Boswell-Syme | 8/1852 | BIRM |
| Herminium monorchis | GB, VC17 Surrey, Headley | John Thomas Irvine Boswell-Syme | Botanical Society of London Augustin Ley John Thomas Irvine Boswell-Syme | 7/1853 | BIRM |
| Herminium monorchis | GB, VC17 Surrey, Mickleham | John Thomas Irvine Boswell-Syme | Botanical Society of London Augustin Ley | 6/1854 | BIRM |
| Carex divulsa subsp. divulsa | GB, VC17 Surrey, Mickleham | John Thomas Irvine Boswell-Syme | Augustin Ley | 7/1866 | BIRM |
| Arabis glabra | GB, VC17 Surrey, Moulsey Hurst | John Thomas Irvine Boswell-Syme | Botanical Society of London Augustin Ley John Thomas Irvine Boswell-Syme | 7/1852 | BIRM |
| Schoenoplectus lacustris | GB, VC17 Surrey, Putney | John Gilbert Baker John Thomas Irvine Boswell-Syme | George Stephen West | 8/1852 | BIRM |
| Damasonium alisma | GB, VC17 Surrey, Putney Heath | John Thomas Irvine Boswell-Syme | Botanical Society of London George Stephen West John Thomas Irvine Boswell-Syme | 8/1852 | BIRM |
| Damasonium alisma | GB, VC17 Surrey, Putney Heath | John Thomas Irvine Boswell-Syme | Botanical Society of London Harold Stuart Thompson Thomas Clark John Thomas Irvine Boswell-Syme | 10/1852 | BIRM |
| Polygala calcarea | GB, VC17 Surrey, Reigate | John Thomas Irvine Boswell-Syme | George Stephen West Martha Maria Atwood | 6/1853 | BIRM |
| Sorbus aria | GB, VC17 Surrey, Reigate Hill | John Thomas Irvine Boswell-Syme | Augustin Ley | 9/1864 | BIRM |
| Sorbus aria | GB, VC17 Surrey, Reigate Hill | John Thomas Irvine Boswell-Syme | Augustin Ley | 9/1864 | BIRM |
| Sorbus aria | GB, VC17 Surrey, Reigate Hill | John Thomas Irvine Boswell-Syme | Augustin Ley | 1883 | BIRM |
| Myosotis ramosissima | GB, VC17 Surrey, Richmond | John Thomas Irvine Boswell-Syme | Botanical Society of London Thomas Clark | 5/1853 | BIRM |
| Carex acuta | GB, VC17 Surrey, Richmond | John Thomas Irvine Boswell-Syme | George Stephen West | 6/1882 | BIRM |
| Schoenoplectus triqueter | GB, VC17 Surrey, River Thames at Putney | John Thomas Irvine Boswell-Syme | | 8/1852 | BIRM |
| Erophila verna var. spathulata | GB, VC17 Surrey, Thames Ditton Cultivated | John Thomas Irvine Boswell-Syme | Augustin Ley | 1861 | BIRM |
| Nymphoides peltata | GB, VC17 Surrey, Walton Bridge | John Thomas Irvine Boswell-Syme | Botanical Society of London Harold Stuart Thompson Thomas Clark | 7/1852 | BIRM |
| Populus alba x tremula = P. x canescens | GB, VC18 South Essex, Wanstead | John Thomas Irvine Boswell-Syme | Donor Unknown John Thomas Irvine Boswell-Syme | 1853 | BIRM |
| Lepidium latifolium | GB, VC19 North Essex, Braintree | John Thomas Irvine Boswell-Syme | Augustin Ley | 4/1867 | BIRM |
| Peucedanum officinale | GB, VC19 North Essex, Kirby le Soken | John Thomas Irvine Boswell-Syme | Augustin Ley | 9/1867 | BIRM |
| Bupleurum tenuissimum | GB, VC19 North Essex, Walton on the Naze | John Thomas Irvine Boswell-Syme | Augustin Ley | 9/1867 | BIRM |
| Chenopodium chenopodioides | GB, VC21 Middlesex | John Thomas Irvine Boswell-Syme | Augustin Ley | 1851 | BIRM |
| Chenopodium polyspermum | GB, VC21 Middlesex | John Thomas Irvine Boswell-Syme | Augustin Ley | 1867 | BIRM |
| Potentilla reptans | GB, VC21 Middlesex, Belsize Park | John Thomas Irvine Boswell-Syme | Augustin Ley | 8/1867 | BIRM |
| Chenopodium ficifolium | GB, VC21 Middlesex, Camden Town | John Gilbert Baker John Thomas Irvine Boswell-Syme | Donor Unknown | 10/1850 | BIRM |
| Chenopodium glaucum | GB, VC21 Middlesex, Hampstead | John Thomas Irvine Boswell-Syme | Augustin Ley | 9/1867 | BIRM |
| Mentha pulegium | GB, VC21 Middlesex, Hampstead Heath | John Thomas Irvine Boswell-Syme | Botanical Society of London George Stephen West John Thomas Irvine Boswell-Syme | 9/1850 | BIRM |
| Glyceria fluitans | GB, VC21 Middlesex, Hampstead Heath | John Thomas Irvine Boswell-Syme | Augustin Ley | 6/1861 | BIRM |
| Persicaria minor | GB, VC21 Middlesex, Little Chelsea | John Thomas Irvine Boswell-Syme | Botanical Society of London George Stephen West | 8/1852 | BIRM |
| Centaurea jacea | GB, VC21 Middlesex, Twickenham | John Thomas Irvine Boswell-Syme | Augustin Ley | 9/1867 | BIRM |
| Acorus calamus | GB, VC21 Middlesex, Walton Bridge | John Thomas Irvine Boswell-Syme | Botanical Society of London Harold Stuart Thompson Thomas Clark | 7/1852 | BIRM |
| Chenopodium ficifolium | GB, VC17,VC21, Camden Town | John Thomas Irvine Boswell-Syme | George Stephen West Botanical Society of London John Thomas Irvine Boswell-Syme | 8/1850 | BIRM |