| Apium graveolens | IE, VCH9 Co. Clare, Killadysert | Matilda Cullen Knowles | Dublin Museum Matilda Cullen Knowles | 7/8/1907 | GALW |
| Atriplex glabriuscula | IE, VCH8 Co. Limerick, Foynes Island | Matilda Cullen Knowles | | 9/1905 | GALW |
| Atriplex prostrata | IE, VCH8,VCH9, Foynes Island | Matilda Cullen Knowles | | 6/9/1905 | GALW |
| Atriplex prostrata | IE, VCH8 Co. Limerick, Glenstar | Matilda Cullen Knowles | | 9/1905 | GALW |
| Calluna vulgaris | IE, VCH36 Tyrone, Bessy Bell | Matilda Cullen Knowles | Science & Art Museum Dublin | 7/1896 | DBC |
| Carex appropinquata | IE, VCH9 Co. Clare, Dromoland | Matilda Cullen Knowles | Matilda Cullen Knowles | 7/1908 | BM |
| Carex appropinquata | IE, VCH9 Co. Clare, Dromoland | Matilda Cullen Knowles | Matilda Cullen Knowles | 6/1908 | BM |
| Carex appropinquata | IE, VCH9 Co. Clare, Dromoland | Matilda Cullen Knowles | Arthur Bennett Matilda Cullen Knowles Charles Edgar Salmon | 29/6/1908 | BM |
| Carex aquatilis | IE, VCH36 Tyrone, Strabane | Matilda Cullen Knowles | Harold Stuart Thompson | 7/1896 | BIRM |
| Carex aquatilis | IE, VCH39 Co. Antrim, Ballymena | Matilda Cullen Knowles | Robert Lloyd Praeger | 6/1895 | DBC |
| Ceratophyllum demersum | IE, VCH8 Co. Limerick, Lough Gur | Matilda Cullen Knowles | | 14/8/1900 | BIRM |
| Chenopodium suecicum | IE, VCH19 Co. Kildare, Straffan | Matilda Cullen Knowles | Science & Art Museum Dublin | 10/1904 | GALW |
| Daboecia cantabrica | IE, Mayo, Carrowdrisky | Matilda Cullen Knowles | National Museum Ireland Matilda Cullen Knowles | 22/6/1909 | GALW |
| Daucus carota | IE, VCH27 West Mayo, Murrisk | Matilda Cullen Knowles | Matilda Cullen Knowles | 7/1909 | GALW |
| Dryas octopetala | IE, VCH9 Co. Clare, Burren | Matilda Cullen Knowles | Harold Stuart Thompson | 6/1900 | BIRM |
| Eruca vesicaria subsp. sativa | IE, VCH19 Co. Kildare, Straffan | Matilda Cullen Knowles | Irish National Herbarium Glasnevin Dublin Science & Art Museum Dublin | 8/1904 | GALW |
| Inula crithmoides | IE, VCH21 Co. Dublin, Howth | Matilda Cullen Knowles | Harold Stuart Thompson | 8/1905 | BIRM |
| Lepidium ruderale | IE, VCH19 Co. Kildare, Straffan | Matilda Cullen Knowles | Irish National Herbarium Glasnevin Dublin Science & Art Museum Dublin | 8/1904 | GALW |
| Leucojum aestivum | IE, VCH9 Co. Clare, Whitehall Creek | Robert Donough O'Brien | Augustin Ley Edward Shearburn Marshall Matilda Cullen Knowles | 30/5/1909 | BIRM |
| Leucojum aestivum | IE, VCH12 Co. Wexford, Macmine Junction | Matilda Cullen Knowles | Harold Stuart Thompson | 29/5/1909 | BIRM |
| Mentha aquatica x spicata = M. x piperita | IE, VCH8 Co. Limerick, White River | Matilda Cullen Knowles | Science & Art Museum Dublin | 6/1903 | DBN |
| Mentha aquatica x spicata = M. x piperita | IE, VCH36 Tyrone, Strabane | Matilda Cullen Knowles | Science & Art Museum Dublin | 7/1896 | DBN |
| Mentha arvensis x aquatica = M. x verticillata | IE, VCH8 Co. Limerick, West Ardagh | Matilda Cullen Knowles | Science & Art Museum Dublin | 9/1908 | DBN |
| Mentha arvensis x aquatica = M. x verticillata | IE, VCH9 Co. Clare, Killadysart | Matilda Cullen Knowles | Dublin Museum Matilda Cullen Knowles | 8/1907 | DBN |
| Narcissus tazetta x poeticus = N. x medioluteus | IE, VCH9 Co. Clare, Parteen | Matilda Cullen Knowles | National Museum Ireland Harold Stuart Thompson | 26/4/1907 | BIRM |
| Narthecium ossifragum | IE, VCH36 Tyrone, Omagh | Matilda Cullen Knowles | | 7/1896 | DBC |
| Petroselinum sativum | IE, VCH9 Co. Clare, Canon Island | Matilda Cullen Knowles | Dublin Museum Matilda Cullen Knowles | 8/1907 | GALW |
| Puccinellia maritima | IE, VCH8 Co. Limerick, Robertstow Creek | Matilda Cullen Knowles | Watson Botanical Exchange Club Augustin Ley Arthur Bennett | 6/1904 | BIRM |
| Puccinellia maritima | IE, VCH9 Co. Clare, Inishmacnaghtan | Matilda Cullen Knowles | Science & Art Museum Dublin Matilda Cullen Knowles | 6/1908 | BIRM |
| Salix viminalis x caprea = S. x smithiana | IE, VCH8 Co. Limerick, West Loghill | Matilda Cullen Knowles | Science & Art Museum Dublin | 6/1904 | DBN |
| Salix viminalis x caprea = S. x smithiana | IE, VCH27 West Mayo, Westport | Matilda Cullen Knowles | National Museum Ireland Matilda Cullen Knowles | 4/7/1909 | DBN |
| Salix viminalis x caprea = S. x smithiana | IE, VCH36 Tyrone | Matilda Cullen Knowles | Science & Art Museum Dublin | 9/1900 | DBN |
| Salix viminalis x caprea = S. x smithiana | IE, VCH36 Tyrone, Foyle | Matilda Cullen Knowles | Science & Art Museum Dublin | 9/1900 | DBN |
| Salix viminalis x cinerea = S. x holosericea | IE, VCH8 Co. Limerick, Loghill | Matilda Cullen Knowles | Science & Art Museum Dublin | 6/1904 | DBN |
| Scandix pecten-veneris | IE, VCH8 Co. Limerick, Rathkeale | Matilda Cullen Knowles | | 29/5/1906 | GALW |
| Scandix pecten-veneris | IE, VCH9 Co. Clare, Killadysert | Matilda Cullen Knowles | Dublin Museum Matilda Cullen Knowles | 8/1907 | GALW |
| Scandix pecten-veneris | IE, VCH9 Co. Clare, Killadysert | Matilda Cullen Knowles | Dublin Museum Matilda Cullen Knowles | 8/1907 | GALW |
| Scrophularia umbrosa | IE, VCH35 West Donegal, Leahan | Matilda Cullen Knowles | Harold Stuart Thompson | 19/8/1905 | BIRM |
| Spergularia marina | IE, VCH8,VCH9, Foynes | Matilda Cullen Knowles | Irish National Herbarium Glasnevin Dublin Science & Art Museum Dublin | 6/1904 | GALW |
| Spiranthes romanzoffiana | IE, VCH39,VCH40, Kilrea | Matilda Cullen Knowles | Harold Stuart Thompson | 7/1897 | BIRM |
| Stachys palustris | IE, VCH39 Co. Antrim, Cullybackey | Matilda Cullen Knowles | Robert Lloyd Praeger | 7/1893 | DBC |
| Viola hirta | IE, VCH8 Co. Limerick, Morenane | Matilda Cullen Knowles | | 3/6/1906 | SLBI |