| Rubus babingtonianus | GB, VC16 West Kent, Westerham | William Charles Richard Watson | William Charles Richard Watson | 4/7/1947 | SLBI |
| Rubus bakerianus | GB, VC17 Surrey, Putney Heath | William Charles Richard Watson | William Charles Richard Watson | 29/7/1935 | SLBI |
| Rubus bartonii | GB, VC48 Merionethshire, Dolgellau | William Charles Richard Watson | William Charles Richard Watson | 26/6/1948 | SLBI |
| Rubus bartonii | GB, VC48 Merionethshire, Dolgellau | William Charles Richard Watson | William Charles Richard Watson | 26/6/1948 | SLBI |
| Rubus bercheriensis | GB, VC16 West Kent, West Wickham | William Charles Richard Watson | William Charles Richard Watson | 12/7/1950 | SLBI |
| Rubus bloxamii | GB, VC16 West Kent, Tunbridge Wells | William Charles Richard Watson | | 8/7/1937 | SLBI |
| Rubus boraeanus | GB, VC18 South Essex, Danbury | William Charles Richard Watson | William Charles Richard Watson | 30/7/1949 | SLBI |
| Rubus boraeanus | GB, VC18 South Essex, Danbury | William Charles Richard Watson | William Charles Richard Watson | 30/7/1949 | SLBI |
| Rubus boraeanus | GB, VC27 East Norfolk, Ringland | William Charles Richard Watson | William Charles Richard Watson | 12/7/1946 | SLBI |
| Rubus botryeros | GB, VC3 South Devon, Hemerdon | | William Charles Richard Watson | 4/7/1937 | SLBI |
| Rubus boulayi | GB, VC9 Dorset, Branksome Park, Bournemouth | William Charles Richard Watson | William Charles Richard Watson | 10/9/1936 | SLBI |
| Rubus breconensis | GB, VC35 Monmouthshire, Glanau | William Charles Richard Watson | | 3/9/1952 | SLBI |
| Rubus breconensis | GB, VC42 Breconshire, Brecon | William Charles Richard Watson | William Charles Richard Watson | 3/9/1952 | SLBI |
| Rubus brevistaminosus | GB, VC16 West Kent, Rusthall Common | William Charles Richard Watson | William Charles Richard Watson | 21/9/1935 | SLBI |
| Rubus briggsianus | GB, VC3 South Devon, Cornwood | William Charles Richard Watson | William Charles Richard Watson | 4/7/1951 | SLBI |
| Rubus calvatus | GB, VC16 West Kent, Hosey Common | William Charles Richard Watson | William Charles Richard Watson | 20/8/1951 | SLBI |
| Rubus cambrensis | GB, Ambiguous locality (GB), Bickley Cultivated | William Charles Richard Watson | William Charles Richard Watson | 2/6/1938 1/8/1938 | SLBI |
| Rubus campaniensis | GB, VC16 West Kent, Hosey Common | William Charles Richard Watson | | 21/7/1938 28/8/1951 | SLBI |
| Rubus campaniensis | GB, VC16 West Kent, Hosey Common | William Charles Richard Watson | | 28/8/1951 | SLBI |
| Rubus canterburiensis | GB, VC15 East Kent, Canterbury | William Charles Richard Watson | | | SLBI |
| Rubus cantianus | GB, VC15 East Kent, Sutton Valence | William Charles Richard Watson | | 30/7/1938 | SLBI |
| Rubus cantianus | GB, VC16 West Kent, Bostall Heath | William Charles Richard Watson | | 29/7/1934 | SLBI |
| Rubus cardiophyllus | GB, VC17 Surrey, Barnes Common | William Charles Richard Watson | William Charles Richard Watson | 18/7/1928 | SLBI |
| Rubus carnkiefensis | GB, VC1 West Cornwall, Carnkief | William Charles Richard Watson | William Charles Richard Watson | 11/7/1951 | SLBI |
| Rubus celticus | GB, VC48 Merionethshire, Dolgellau | William Charles Richard Watson | William Charles Richard Watson | 27/6/1948 | SLBI |
| Rubus chamaemorus | GB, VC88 Mid Perthshire, Ben Lawers | William Charles Richard Watson | | 8/7/1927 | SLBI |
| Rubus chloophyllus | GB, VC14 East Sussex, Benhall Mill Lane | William Charles Richard Watson | William Charles Richard Watson | 24/7/1947 | SLBI |
| Rubus chloophyllus | GB, VC14 East Sussex, Benhall Mill Lane | William Charles Richard Watson | William Charles Richard Watson | 24/7/1947 | SLBI |
| Rubus chloophyllus | GB, VC14 East Sussex, Uckfield,Budletts Common Cultivated | William Charles Richard Watson | | 1948 | SLBI |
| Rubus chrysoxylon | GB, VC49 Caernarvonshire, Bangor Cultivated | | William Charles Richard Watson | 14/7/1952 | SLBI |
| Rubus cinerosus | GB, VC16 West Kent, Plumstead Cultivated | William Charles Richard Watson | | 7/1951 | SLBI |
| Rubus cinerosus | GB, VC16 West Kent, Plumstead Cultivated | Edward Charles Wallace | William Charles Richard Watson | 7/1951 | SLBI |
| Rubus cissburiensis | GB, VC13 West Sussex, Devil's Dyke | William Charles Richard Watson | Job Edward Lousley William Charles Richard Watson | 7/1926 | SLBI |
| Rubus confertiflorus | GB, VC22 Berkshire, Boars Hill | William Charles Richard Watson | William Charles Richard Watson | | SLBI |
| Rubus conjungens | GB, VC15 East Kent, Covet Wood | F R John Ezra Woodhead William Charles Richard Watson | William Charles Richard Watson | 7/7/1950 | SLBI |
| Rubus conjungens | GB, VC33 East Gloucestershire, Bourton on the Water | William Hobson Mills | William Charles Richard Watson | 2/8/1949 | SLBI |
| Rubus conjungens | GB, VC33 East Gloucestershire, Bourton on the Water | William Hobson Mills | William Charles Richard Watson | 2/8/1949 | SLBI |
| Rubus coombensis | GB, VC3 South Devon, Bickleigh | William Charles Richard Watson | William Charles Richard Watson | 6/7/1951 | SLBI |
| Rubus cornubiensis | GB, VC3 South Devon, Honicknowle | William Charles Richard Watson | William Charles Richard Watson | 7/7/1939 | SLBI |
| Rubus cornubiensis | GB, VC3 South Devon, Honicknowle | William Charles Richard Watson | William Charles Richard Watson | 17/7/1939 | SLBI |