| Mentha aquatica x arvensis var paludosa | GB, VC13 West Sussex, Linch | Joseph Edward Little Rowland John Burdon | Watson Botanical Exchange Club Job Edward Lousley | 14/8/1929 | SLBI |
| Mentha aquatica x spicata = M. x piperita | GB, VC17 Surrey, Chiddingfold | Rowland John Burdon | Botanical Society & Exchange Club of The British Isles Job Edward Lousley | 19/9/1930 | SLBI |
| Mentha aquatica x spicata = M. x piperita | GB, VC17 Surrey, Chiddingfold | Rowland John Burdon | Isaac A Helsby | 13/9/1930 | SLBI |
| Mentha aquatica x spicata = M. x piperita var. citrata | GB, VC17 Surrey, Chiddingfold | Rowland John Burdon | Botanical Exchange Club of The British Isles | 19/9/1930 | K |
| Mentha arvensis x aquatica = M. x verticillata | GB, VC13 West Sussex, Linch | Joseph Edward Little Rowland John Burdon | Watson Botanical Exchange Club | 14/8/1929 | SLBI |
| Mentha arvensis x aquatica = M. x verticillata | GB, VC13 West Sussex, Lurgashall | Rowland John Burdon | Botanical Exchange Club of The British Isles | 1/9/1928 | K |
+ | Mentha arvensis x aquatica = M. x verticillata | GB, VC13 West Sussex, Lurgashall | Rowland John Burdon | Botanical Society & Exchange Club of The British Isles | 14/8/1929 | MANCH |
| Mentha arvensis x aquatica x spicata = M. x smithiana | GB, VC17 Surrey, Ansteadbrook | Rowland John Burdon | Watson Botanical Exchange Club Job Edward Lousley | 14/9/1931 | SLBI |
| Mentha arvensis x spicata = M. x gracilis | GB, VC17 Surrey, Shalford Pond | Rowland John Burdon | Botanical Society & Exchange Club of The British Isles | 5/9/1933 | OXF |
| Mentha spicata | GB, VC17 Surrey, Shalford | Rowland John Burdon | Botanical Exchange Club of The British Isles Rowland John Burdon | 7/9/1933 | K |
| Mentha spicata x suaveolens = M. x villosa var. alopecuroides | GB, VC27 East Norfolk, Burgh Saint Margaret | Rowland John Burdon | | 25/8/1926 | OXF |
| Mentha spicata x suaveolens = M. x villosa var. alopecuroides | GB, VC27 East Norfolk, Burgh Saint Margaret | Rowland John Burdon | Botanical Exchange Club of The British Isles J Fraser | 25/8/1926 | K |
| Mercurialis annua | GB, VC13 West Sussex, Chichester | Rowland John Burdon | | 3/10/1921 | SLBI |
| Mimulus | GB, VC13 West Sussex, Linch | Joseph Edward Little Rowland John Burdon | Watson Botanical Exchange Club | 20/8/1928 | SLBI |
| Mimulus moschatus | GB, VC13 West Sussex, Linch | Joseph Edward Little Rowland John Burdon | Watson Botanical Exchange Club Job Edward Lousley | 20/8/1928 | SLBI |
| Mimulus moschatus | GB, VC13 West Sussex, Redford | Rowland John Burdon | Botanical Exchange Club of The British Isles Job Edward Lousley | 20/8/1928 | SLBI |
| Minuartia hybrida subsp. tenuifolia | GB, VC28 West Norfolk, Castle Acre | Rowland John Burdon | Watson Botanical Exchange Club Job Edward Lousley | 28/6/1928 | SLBI |
| Minuartia hybrida subsp. tenuifolia | GB, VC28 West Norfolk, Castle Acre | Rowland John Burdon | Watson Botanical Exchange Club William Hadden Beeby | 25/6/1876 | SLBI |
| Myosotis laxa subsp. caespitosa | GB, VC112 Shetland, Dunrossness | Rowland John Burdon | Watson Botanical Exchange Club | 1924 | SLBI |
| Myosotis scorpioides | GB, VC27 East Norfolk, Burgh Saint Margaret | Rowland John Burdon | Botanical Exchange Club of The British Isles Job Edward Lousley | 8/7/1889 | SLBI |
| Nasturtium sylvestre | GB, VC13 West Sussex, Lurgashall | Rowland John Burdon | Botanical Society & Exchange Club of The British Isles | 25/7/1927 | MANCH |
| Persicaria lapathifolia | GB, VC17 Surrey, Guildford | Rowland John Burdon | Watson Botanical Exchange Club Job Edward Lousley | 25/8/1929 | SLBI |
| Persicaria lapathifolia | GB, VC17 Surrey, Guildford | Rowland John Burdon | Watson Botanical Exchange Club | 25/8/1929 | SLBI |
| Persicaria lapathifolia | GB, VC17 Surrey, Guildford | Rowland John Burdon | Botanical Exchange Club of The British Isles Job Edward Lousley | 7/8/1930 | SLBI |
| Plantago lanceolata | GB, VC112 Shetland, Sandness | Rowland John Burdon | Watson Botanical Exchange Club Harold Stuart Thompson | 17/7/1920 | BIRM |
| Plantago maritima | GB, VC112 Shetland, Baltasound, Unst | Rowland John Burdon | Watson Botanical Exchange Club | 24/7/1920 | SLBI |
| Polypogon monspeliensis | GB, VC13 West Sussex, Thorney Island | Rowland John Burdon | Douglas Montague Heath Frederick Robinson | 10/1917 | BIRM |
+ | Potamogeton friesii | GB, VC27 East Norfolk, Burgh Saint Margaret | Rowland John Burdon | Botanical Society & Exchange Club of The British Isles | 6/7/1929 | MANCH |
| Potamogeton friesii | GB, VC27 East Norfolk, Burgh Saint Margaret | Rowland John Burdon | Botanical Exchange Club of The British Isles Job Edward Lousley | 3/8/1926 | SLBI |
| Prunus cerasus | GB, VC13 West Sussex, Lurgashall | Rowland John Burdon | | 4/1929 | SLBI |
| Prunus domestica subsp. insititia | GB, VC13 West Sussex, Chichester | Rowland John Burdon | Watson Botanical Exchange Club Rowland John Burdon | 31/3/1923 to 13/6/1923 | SLBI |
+ | Puccinellia fasciculata | GB, VC17 Surrey | Rowland John Burdon | Botanical Society & Exchange Club of The British Isles Charles Bailey | 10/6/1916 | MANCH |
| Puccinellia maritima | GB, VC11 South Hampshire, Hayling Island | Rowland John Burdon | Watson Botanical Exchange Club Harold Stuart Thompson | | BIRM |
| Puccinellia maritima | GB, VC13 West Sussex, Chichester Harbour | Rowland John Burdon | Watson Botanical Exchange Club Harold Stuart Thompson | 6/1917 | BIRM |
| Puccinellia maritima | GB, VC13 West Sussex, Pagham Harbour | Rowland John Burdon | Harold Stuart Thompson Watson Botanical Exchange Club | 1/6/1919 | BIRM |
| Puccinellia maritima | GB, VC13 West Sussex, Pagham Harbour | Rowland John Burdon | Watson Botanical Exchange Club Harold Stuart Thompson | 29/6/1917 | BIRM |
| Puccinellia maritima | GB, VC13 West Sussex, Pagham Harbour | Rowland John Burdon | Watson Botanical Exchange Club Harold Stuart Thompson | 29/6/1912 | BIRM |
| Pulicaria vulgaris | GB, VC13 West Sussex, Redford | Rowland John Burdon | Botanical Exchange Club of The British Isles Job Edward Lousley | 20/8/1928 | SLBI |
| Pulicaria vulgaris | GB, VC13 West Sussex, Woolbeding Common | Joseph Edward Little Rowland John Burdon | Watson Botanical Exchange Club | 20/8/1928 | SLBI |
| Pulicaria vulgaris | GB, VC13 West Sussex, Woolbeding Common | Joseph Edward Little Rowland John Burdon | Watson Botanical Exchange Club Job Edward Lousley | 20/8/1928 | SLBI |