| Rumex crispus x obtusifolius = R. x pratensis | IE, VCH23 Westmeath, Knockdrin | William Richardson Linton | Botanical Exchange Club of The British Isles Charles Bailey Harry Corbyn Levinge | 27/7/1895 | MANCH |
| Rumex crispus | IE, VCH23 Westmeath, Knockdrin | William Richardson Linton | Botanical Exchange Club of The British Isles Augustin Ley Harry Corbyn Levinge | 27/7/1895 | BIRM |
| Rubus rubristylus | IE, VCH23 Westmeath, Crooked Wood | Harry Corbyn Levinge | Harry Corbyn Levinge | 6/8/1895 | ABS |
| Rubus rubristylus | IE, VCH23 Westmeath, Crooked Wood | Harry Corbyn Levinge | | 6/8/1895 | SLBI |
| Rubus pyramidalis | IE, VCH23 Westmeath, Knock Drui | Harry Corbyn Levinge | Harry Corbyn Levinge William Hunt Painter | 31/7/1895 | SHYB |
| Rubus macrophyllus var. schlechtendalii | IE, VCH23 Westmeath, Knock | Harry Corbyn Levinge | | 28/8/1895 | ABS |
| Rubus macrophyllus var. schlechtendalii | IE, VCH23 Westmeath, Knockdrin | Harry Corbyn Levinge | Harry Corbyn Levinge William Hunt Painter | 28/8/1895 | ABS |
| Rubus leptothyrsos | IE, VCH23 Westmeath, Knock Drui, Co. West Meath | Harry Corbyn Levinge | Harry Corbyn Levinge | 31/7/1895 | ABS |
| Rubus fuscus | IE, VCH23 Westmeath, Knock | Harry Corbyn Levinge | Harry Corbyn Levinge William Hunt Painter | 17/7/1894 to 20/8/1894 | SHYB |
| Rubus amplificatus | IE, VCH23 Westmeath, Knock Drui, Co. West Meath | Harry Corbyn Levinge | Harry Corbyn Levinge | 28/8/1895 | SLBI |
| Rosa villosa | IE, VCH23 Westmeath, Knock Ross | Harry Corbyn Levinge | Irish National Herbarium Glasnevin Dublin Science & Art Museum Dublin Harry Corbyn Levinge | 9/9/1892 | GALW |
| Rhinanthus minor subsp. stenophyllus | IE, VCH23 Westmeath, Bog of Lynn | Edward Shearburn Marshall | Harry Corbyn Levinge | 22/7/1895 | SLBI |
| Rhinanthus minor | IE, VCH23 Westmeath, Mullingar, Bog of Lynn | Edward Shearburn Marshall | Botanical Exchange Club of The British Isles Harry Corbyn Levinge William Hunt Painter | 22/7/1895 | ABS |
| Rhinanthus | IE, VCH23 Westmeath, Mullingar, Bog of Lynn | Edward Shearburn Marshall | Harry Corbyn Levinge William Hunt Painter | 22/7/1895 | SHYB |
| Ranunculus trichophyllus | IE, VCH23 Westmeath, Knock Drui, Co. West Meath | Harry Corbyn Levinge | | 10/7/1893 | SHYB |
| Ranunculus trichophyllus | IE, VCH23 Westmeath, Knock Drui, Co. West Meath | Harry Corbyn Levinge | Harry Corbyn Levinge William Hunt Painter | 2/4/1895 | SHYB |
| Ranunculus trichophyllus | IE, VCH23 Westmeath, Knock Drui, Co. West Meath | Harry Corbyn Levinge | Harry Corbyn Levinge William Hunt Painter | 15/6/1894 | ABS |
| Ranunculus trichophyllus | IE, VCH23 Westmeath, Knockdrin | Harry Corbyn Levinge | Harry Corbyn Levinge | 2/6/1895 | SHYB |
| Ranunculus baudotii x trichophyllus = R. x segretii | IE, VCH23 Westmeath, Knockdrin | Harry Corbyn Levinge | Harry Corbyn Levinge William Hunt Painter | 2/6/1895 | ABS |
| Ranunculus baudotii | IE, VCH9 Co. Clare, New Quay | Harry Corbyn Levinge | William Hunt Painter | 18/5/1892 | ABS |
| Pyrola rotundifolia | IE, VCH23 Westmeath, Loughanstown | Harry Corbyn Levinge | Harold Stuart Thompson Harry Corbyn Levinge | 21/6/1892 | BIRM |
| Pyrola rotundifolia | IE, VCH23 Westmeath, Scragh Bog | Harry Corbyn Levinge Henry Groves James Groves | Allan Octavian Hume Henry & James Groves | 4/8/1892 | SLBI |
| Pyrola rotundifolia | IE, Loughanstown | Harry Corbyn Levinge James Groves | Allan Octavian Hume | 14/8/1892 | SLBI |
| Potentilla fruticosa | IE, VCH9 Co. Clare, Ballyvaughan | Harry Corbyn Levinge | Dublin Museum Irish National Herbarium Glasnevin Dublin Harry Corbyn Levinge | 17/5/1892 | GALW |
| Potentilla fruticosa | IE, VCH9 Co. Clare, Turlough | Harry Corbyn Levinge | Harold Stuart Thompson Harry Corbyn Levinge | 17/5/1892 | BIRM |
| Potamogeton lucens | IE, VCH23 Westmeath, Lough Derravaragh | Harry Corbyn Levinge | | 9/8/1892 | MANCH |
| Potamogeton lucens | IE, VCH23 Westmeath, Lough Derravaragh | Harry Corbyn Levinge | Botanical Exchange Club of The British Isles Augustin Ley | 9/8/1892 | BIRM |
| Potamogeton gramineus | IE, VCH25 Co. Roscommon, River Suck | Harry Corbyn Levinge | Watson Botanical Exchange Club Arthur Bennett Harold Stuart Thompson | 26/7/1891 | BIRM |
+ | Potamogeton friesii | IE, VCH20 Co. Wicklow, Loch Derravaragh | Harry Corbyn Levinge | Charles Bailey Harry Corbyn Levinge | 24/7/1895 | MANCH |
| Potamogeton friesii | IE, VCH23 Westmeath, Lough Derravaragh | Harry Corbyn Levinge | | 24/7/1895 | BIRM |
| Potamogeton coloratus x berchtoldii = P. x lanceolatus | IE, VCH9 Co. Clare, Cahir River | Patrick Bernard O'Kelly | Dublin Museum Harry Corbyn Levinge Harold Stuart Thompson | 12/7/1894 | BIRM |
| Polypodium vulgare | IE, VCH23 Westmeath, Knock Ross | Harry Corbyn Levinge | Botanical Exchange Club of The British Isles Augustin Ley Harry Corbyn Levinge | 17/6/1892 | BIRM |
| Plantago maritima | GB, VC49 Caernarvonshire, Criccieth | Harry Corbyn Levinge | James Sykes Gamble | 8/1884 | K |
| Pimpinella major | IE, VCH9 Co. Clare, Kilrush | Patrick Bernard O'Kelly | Harry Corbyn Levinge | 13/7/1893 | GALW |
| Pimpinella major | IE, VCH9 Co. Clare, Scattery Island | Patrick Bernard O'Kelly | Harry Corbyn Levinge | 13/7/1893 | GALW |
| Pilosella aurantiaca | IE, VCH17 North-east Galway, Mount Bellew | M Bayly | Harry Corbyn Levinge | 19/7/1894 | ABS |
| Pilosella aurantiaca | IE, Galway, Mount Bellow | Harry Corbyn Levinge | Harry Corbyn Levinge M Bayly | 19/7/1894 | SHYB |
| Oenanthe fistulosa | IE, VCH20 Co. Wicklow, The Murrough | Harry Corbyn Levinge | | 10/7/1890 | K |
| Oenanthe fistulosa | IE, VCH23 Westmeath, Lough Ennell | Harry Corbyn Levinge | Harry Corbyn Levinge | 6/8/1891 | K |
| Neotinea maculata | IE, VCH9 Co. Clare, Ballyvaughan | Harry Corbyn Levinge | Augustin Ley Harry Corbyn Levinge | 18/5/1892 | BIRM |