| Poa nemoralis | GB, VC20 Hertfordshire, Welwyn | Joseph Edward Little William Robert Sherrin | The South London Botanical Institute Watson Botanical Exchange Club Harold Stuart Thompson | 6/1925 | BIRM |
| Polypogon monspeliensis | GB, VC13 West Sussex, Thorney Island | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 11/10/1916 | BIRM |
| Populus nigra x deltoides = P. x canadensis | GB, VC20 Hertfordshire, Saint Ippolyts Cultivated | Joseph Edward Little | Harold Stuart Thompson | 15/4/1925 3/9/1925 | BIRM |
| Potentilla norvegica | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 10/9/1919 | BIRM |
| Prunus cerasus | GB, VC20 Hertfordshire, Hitchin | Harold Stuart Thompson Joseph Edward Little | Harold Stuart Thompson | 5/1913 | BIRM |
| Prunus padus | GB, VC28 West Norfolk, Beechamwell | Anna Luddington Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 30/7/1917 | BIRM |
| Pterotheca nemausensis | GB, VC30 Bedfordshire, Wilbury Hill | Joseph Edward Little | Harold Stuart Thompson Joseph Edward Little | 17/5/1921 29/5/1921 | BIRM |
| Ranunculus acris | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Harold Stuart Thompson Joseph Edward Little | 9/6/1921 | BIRM |
| Ranunculus penicillatus subsp. pseudofluitans | GB, VC20,VC30, Ickleford | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 29/6/1922 | BIRM |
| Reseda lutea | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 2/11/1913 | BIRM |
| Rumex hydrolapathum | GB, VC13 West Sussex, Fishbourne | Rowland John Burdon | Harold Stuart Thompson Joseph Edward Little Watson Botanical Exchange Club | 30/7/1916 | BIRM |
| Sagina boydii subsp. apetala | GB, VC13 West Sussex, Coates | Joseph Edward Little | Harold Stuart Thompson Joseph Edward Little | 13/7/1922 | BIRM |
| Sagina boydii subsp. apetala | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Harold Stuart Thompson | 2/10/1926 | BIRM |
| Salicornia | GB, VC13 West Sussex, Thorney Island | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 11/10/1916 | BIRM |
| Salicornia ramosissima | GB, VC13 West Sussex, Thorney | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 11/10/1916 | BIRM |
| Salix alba var. caerulea | GB, VC20 Hertfordshire, Saint Ippolyts | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 20/3/1921 5/6/1921 | BIRM |
| Salix daphnoides | GB, VC20 Hertfordshire, Hitchin Cultivated | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 25/3/1931 21/7/1931 | BIRM |
| Salvia | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Harold Stuart Thompson Joseph Edward Little | 7/1922 | BIRM |
| Senecio aquaticus subsp. aquaticus | GB, VC13 West Sussex, Lurgashall | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson | 16/8/1929 to 6/8/1930 | BIRM |
| Senecio aquaticus subsp. aquaticus | GB, VC13 West Sussex, North Chapel | Joseph Edward Little Rowland John Burdon | Watson Botanical Exchange Club Harold Stuart Thompson | 8/1929 | BIRM |
| Silene latifolia x dioica = S. x hampeana | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson | 15/6/1931 | BIRM |
| Symphytum | GB, VC28 West Norfolk, Wretton Fen | Joseph Edward Little | Harold Stuart Thompson | 7/6/1926 | BIRM |
| Symphytum officinale | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 12/9/1921 | BIRM |
| Symphytum officinale x asperum = S. x uplandicum | GB, VC28 West Norfolk, Wretton Fen | Joseph Edward Little | Harold Stuart Thompson | 7/6/1926 | BIRM |
| Tripleurospermum maritimum subsp. vinicaule | GB, VC13 West Sussex, Bosham | Joseph Edward Little | Harold Stuart Thompson | 2/10/1924 | BIRM |
| Tulipa sylvestris | GB, VC26 West Suffolk, Stansfield Cultivated | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson Joseph Edward Little | 15/4/1914 | BIRM |
| Ulmus diversifolia | GB, VC20 Hertfordshire, Wymondley | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson | 16/2/1923 30/8/1923 | BIRM |
| Ulmus glabra x minor x plotii = U. x hollandica | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson | 9/5/1923 to 15/9/1923 | BIRM |
| Ulmus procera | GB, VC20 Hertfordshire, Saint Ippolyts | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson | 23/8/1923 | BIRM |
| Ulmus procera | GB, VC20 Hertfordshire, Saint Ippolyts | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson | 17/5/1923 | BIRM |
| Ulmus procera | GB, VC20 Hertfordshire, Saint Ippolyts | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson | 23/8/1923 | BIRM |
| Verbascum longifolium | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson | 10/1929 to 9/1930 | BIRM |
| Verbascum thapsus x lychnitis = V. x thapsi | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Watson Botanical Exchange Club | 7/1931 | BIRM |
| Verbascum thapsus x nigrum = V. x semialbum | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson | 28/7/1931 | BIRM |
| Verbascum thapsus x nigrum = V. x semialbum | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Harold Stuart Thompson Joseph Edward Little | 11/7/1931 | BIRM |
| Veronica agrestis | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Watson Botanical Exchange Club Harold Stuart Thompson | 16/11/1932 | BIRM |
| Veronica agrestis | GB, VC20 Hertfordshire, Hitchin | Joseph Edward Little | Harold Stuart Thompson | 8/7/1927 | BIRM |
| Veronica arvensis | GB, VC28 West Norfolk, Santon Warren | | Harold Stuart Thompson Joseph Edward Little | 11/6/1926 | BIRM |
| Veronica persica | GB, VC13 West Sussex, Lurgashall | Joseph Edward Little Rowland John Burdon | Harold Stuart Thompson | 23/8/1932 | BIRM |
| Veronica persica | GB, VC20 Hertfordshire, Great Wymondley | Joseph Edward Little | Harold Stuart Thompson | 17/10/1932 | BIRM |