| Hydrilla verticillata var. pomeranica | GB, VC69 Westmorland, Esthwaite Water | William Arthur Sledge | Martin F Gardner & Sabina G Knees William Arthur Sledge | 3/8/1933 | E |
| Hydrilla verticillata | IE, VCH16 West Galway, Connemara | William Arthur Sledge | Robert MacKechnie William Arthur Sledge | 10/8/1939 | E |
| Juncus alpinoarticulatus | GB, VC65 North-west Yorkshire, Wynch Bridge | William Arthur Sledge | William Arthur Sledge | 18/8/1940 | SLBI |
| Juncus alpinoarticulatus | GB, VC66 County Durham, Widdybank Fell, Teesdale | Edward Charles Wallace William Arthur Sledge | | 21/8/1943 | SLBI |
| Juncus compressus | GB, VC64 Mid-west Yorkshire, Fairburn, Newton | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 21/7/1937 | SLBI |
+ | Juncus compressus | GB, VC64 Mid-west Yorkshire, Newton | William Arthur Sledge | Botanical Society & Exchange Club of The British Isles William Arthur Sledge | 21/7/1937 | MANCH |
| Juncus gerardii | GB, VC63 South-west Yorkshire, Hook | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 28/7/1937 | SLBI |
| Juncus gerardii | GB, VC64 Mid-west Yorkshire, Newton Ings | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 21/7/1937 | SLBI |
| Lathyrus palustris | GB, VC61 South-east Yorkshire, Beverley | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 22/7/1937 | SLBI |
| Luronium natans | GB, VC59 South Lancashire, Littleborough | William Arthur Sledge | Robert MacKechnie William Arthur Sledge | 1/10/1949 | E |
| Lysimachia thyrsiflora | GB, VC62 North-east Yorkshire, Thirsk, Carlton Carr | William Arthur Sledge | William Arthur Sledge | 28/6/1936 | SLBI |
| Melampyrum pratense | IE, VCH1 South Kerry, Caragh | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 8/8/1938 | SLBI |
| Mentha aquatica x spicata = M. x piperita | GB, VC64 Mid-west Yorkshire, Cookridge | William Arthur Sledge | Botanical Exchange Club of The British Isles William Arthur Sledge | 26/9/1928 | K |
| Mentha aquatica x spicata = M. x piperita | GB, VC64 Mid-west Yorkshire, Cookridge | William Arthur Sledge | Botanical Exchange Club of The British Isles William Arthur Sledge | 26/9/1928 | OXF |
| Mentha arvensis x spicata = M. x gracilis | GB, VC63 South-west Yorkshire, Sowerby Bridge | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 30/8/1941 | SLBI |
| Meum athamanticum | GB, VC65 North-west Yorkshire, Castley | William Arthur Sledge | Botanical Exchange Club of The British Isles William Arthur Sledge | 6/7/1932 | SLBI |
| Meum athamanticum | GB, VC65 North-west Yorkshire, Sedbergh | William Arthur Sledge | Botanical Exchange Club of The British Isles William Arthur Sledge | 6/7/1932 | K |
| Meum athamanticum | GB, VC65 North-west Yorkshire, Sedbergh | William Arthur Sledge | Botanical Exchange Club of The British Isles J Fraser William Arthur Sledge | 6/7/1932 | K |
| Meum athamanticum | GB, VC65 North-west Yorkshire, Sedbergh | William Arthur Sledge | Botanical Exchange Club of The British Isles Job Edward Lousley William Arthur Sledge | 6/7/1932 | SLBI |
| Oenanthe lachenalii | GB, VC62 North-east Yorkshire, Redcar | William Arthur Sledge | Botanical Exchange Club of The British Isles Job Edward Lousley William Arthur Sledge | 13/9/1931 | SLBI |
| Oenanthe lachenalii | GB, VC62 North-east Yorkshire, Redcar | William Arthur Sledge | Richard Barker Ullman Patrick Martin Hall | 13/9/1932 | SLBI |
| Persicaria minor | GB, VC64 Mid-west Yorkshire, Adel Dam | William Arthur Sledge | Botanical Exchange Club of The British Isles Job Edward Lousley William Arthur Sledge | 10/9/1927 | SLBI |
| Potamogeton alpinus | GB, VC69 Westmorland, Blelham Tarn | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 5/8/1933 | SLBI |
| Potamogeton coloratus | GB, VC61 South-east Yorkshire, Driffield | William Arthur Sledge | Robert MacKechnie William Arthur Sledge | 8/7/1950 | E |
| Potamogeton coloratus x berchtoldii = P. x lanceolatus | IE, VCH9 Co. Clare, Caher River | William Arthur Sledge | Robert MacKechnie | 10/8/1935 | E |
| Potamogeton epihydrus | GB, VC63 South-west Yorkshire, Elland | William Arthur Sledge | Botanical Exchange Club of The British Isles Job Edward Lousley William Arthur Sledge | 4/8/1926 | SLBI |
| Potamogeton gramineus | GB, VC69 Westmorland, Windermere | William Arthur Sledge | William Arthur Sledge | 29/6/1932 | SLBI |
| Potamogeton natans x gramineus = P. x sparganiifolius | IE, VCH16 West Galway, Bealanabrack River | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 9/8/1935 | SLBI |
| Potamogeton natans x gramineus = P. x sparganiifolius | IE, VCH16 West Galway, Maam | William Arthur Sledge | Botanical Exchange Club of The British Isles William Arthur Sledge | 9/9/1935 | MANCH |
| Potamogeton natans x gramineus = P. x sparganiifolius | IE, VCH16 West Galway, Maam | William Arthur Sledge | Botanical Exchange Club of The British Isles William Arthur Sledge | 9/8/1935 | SLBI |
| Potamogeton pusillus | GB, VC69 Westmorland, Esthwaite Water | William Arthur Sledge | Botanical Exchange Club of The British Isles Job Edward Lousley William Arthur Sledge | 29/6/1932 | SLBI |
| Pyrola rotundifolia | GB, VC68 North Northumberland, Newham | Patrick Martin Hall William Arthur Sledge | Botanical Exchange Club of The British Isles Patrick Martin Hall | 27/6/1934 | SLBI |
| Pyrola rotundifolia | GB, VC68 North Northumberland, Newham | Patrick Martin Hall William Arthur Sledge | Botanical Exchange Club of The British Isles Job Edward Lousley Patrick Martin Hall | 27/6/1934 | SLBI |
| Pyrola rotundifolia | GB, VC88 Mid Perthshire, Creag an Lochain | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 8/7/1937 | SLBI |
| Pyrola rotundifolia subsp. maritima | GB, VC59 South Lancashire, Ainsdale Dunes | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 4/8/1932 | SLBI |
+ | Pyrola rotundifolia subsp. rotundifolia | GB, VC68 North Northumberland, Newham | Patrick Martin Hall William Arthur Sledge | Botanical Society & Exchange Club of The British Isles Patrick Martin Hall William Harold Pearsall | 27/6/1934 | MANCH |
| Ranunculus lingua | GB, VC70 Cumberland, Newton Regny | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 5/7/1941 | SLBI |
| Rhinanthus angustifolius | GB, VC90 Angus, Arbroath | William Arthur Sledge | William Arthur Sledge | 14/7/1937 | SLBI |
| Rhinanthus angustifolius | GB, VC90 Angus, East Haven | William Arthur Sledge | Job Edward Lousley William Arthur Sledge | 14/7/1937 | SLBI |
| Scheuchzeria palustris | GB, VC88 Mid Perthshire, Rannoch Station | Robert MacKechnie William Arthur Sledge | Robert MacKechnie | 4/8/1946 | E |