| Orobanche alba | IE, VCH39 Co. Antrim, Cave Hill, Belfast | Samuel Alexander Stewart | Augustin Ley | 8/7/1871 | BIRM |
| Pinguicula grandiflora | IE, VCH1 South Kerry, Mangerton | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 25/6/1885 | BIRM |
| Polygala vulgaris | IE, VCH28 Co. Sligo, Benbulben | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 16/7/1879 | BIRM |
+ | Potamogeton perfoliatus x crispus = P. x cooperi | IE, VCH39 Co. Antrim, Sixmile River above Templepatrick | Samuel Alexander Stewart | | 10/8/1894 | BIRM |
| Potamogeton perfoliatus x crispus = P. x cooperi | IE, VCH39 Co. Antrim, Templepatrick | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 10/8/1894 | BIRM |
| Sagina maritima | IE, VCH2 North Kerry, Ballybunnion | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 25/7/1885 | BIRM |
| Salix viminalis x caprea = S. x smithiana | IE, VCH39 Co. Antrim, Kilroot | Samuel Alexander Stewart | George Stephen West | 5/1868 | BIRM |
| Saxifraga umbrosa var. punctata | IE, VCH16 West Galway, Connemara | Samuel Alexander Stewart | Augustin Ley | 10/5/1876 | BIRM |
| Sesleria caerulea | IE, Galway, Galway Bay | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 5/1891 | BIRM |
| Spergularia rupicola | IE, VCH38,VCH39, Belfast | Samuel Alexander Stewart | George Stephen West | 8/1869 | BIRM |
| Valerianella carinata | IE, VCH38 Co. Down, Dundonald | Samuel Alexander Stewart | Augustin Ley | 19/6/1877 | BIRM |
| Viola | IE, VCH9 Co. Clare, Gort | Samuel Alexander Stewart | Augustin Ley | 22/5/1891 | BIRM |
| Viola tricolor subsp. curtisii | IE, VCH39 Co. Antrim, Lough Neagh | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 25/6/1886 | BIRM |
| Zannichellia palustris | IE, VCH38,VCH39, Belfast | Samuel Alexander Stewart | Augustin Ley | 23/8/1876 | BIRM |
| Carex arenaria | IE, VCH38 Co. Down | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Frederick Janson Hanbury | 6/1876 | BM |
| Carex arenaria | IE, VCH38 Co. Down | Samuel Alexander Stewart | Edward Francis Linton | 6/1876 | BM |
| Carex dioica | IE, VCH39 Co. Antrim, Divis Hill | Samuel Alexander Stewart | | 12/5/1866 | BM |
| Carex remota | IE, VCH39 Co. Antrim, Cushendall | Samuel Alexander Stewart | | 28/6/1866 | BM |
| Carex spicata | IE, VCH39 Co. Antrim, Greencastle | Samuel Alexander Stewart | Edward Francis Linton | 19/6/1873 | BM |
| Carex distans | IE, VCH39 Co. Antrim, Black Head | Samuel Alexander Stewart | | 29/6/1872 | BON |
| Equisetum hyemale x variegatum = E. x trachyodon | IE, VCH39 Co. Antrim, Colin Glen | Samuel Alexander Stewart | | 1/7/1872 | BON |
| Eriocaulon aquaticum | IE, VCH16 West Galway, Roundstone | Samuel Alexander Stewart | | 29/7/1867 | BON |
| Mentha aquatica x spicata = M. x piperita | IE, VCH39 Co. Antrim, Carnmoney | Samuel Alexander Stewart | Science & Art Museum Dublin | 14/9/1872 | DBN |
| Mentha aquatica x spicata = M. x piperita | IE, VCH39 Co. Antrim, Carnmoney | Samuel Alexander Stewart | Science & Art Museum Dublin | 12/8/1893 | DBN |
| Mentha aquatica x spicata = M. x piperita | IE, VCH39 Co. Antrim, Masserine Park | Samuel Alexander Stewart | | 2/8/1885 | DBN |
| Mentha arvensis x aquatica = M. x verticillata | IE, VCH38 Co. Down, Saul | Samuel Alexander Stewart | | 8/1897 | DBN |
| Scrophularia auriculata | IE, VCH39 Co. Antrim, Four Mile Burn | Samuel Alexander Stewart | Alexander Somerville | 22/7/1883 | E |
| Apium nodiflorum x inundatum = A. x moorei | IE, VCH38 Co. Down, Downpatrick | Samuel Alexander Stewart | Botanical Exchange Club Charles Bailey | 16/9/1886 | MANCH |
| Apium nodiflorum x inundatum = A. x moorei | IE, VCH38 Co. Down, Downpatrick | Samuel Alexander Stewart | Charles Bailey | 7/1880 | MANCH |
+ | Apium nodiflorum x inundatum = A. x moorei | IE, VCH38 Co. Down, Downpatrick,Quoile | Samuel Alexander Stewart | Charles Bailey | 16/9/1886 | MANCH |
+ | Calamagrostis stricta | IE, VCH39 Co. Antrim, Lough Neagh | Samuel Alexander Stewart | Botanical Exchange Club Charles Bailey | 30/6/1877 | MANCH |
+ | Calamagrostis stricta | IE, VCH39 Co. Antrim, Lough Neagh | Samuel Alexander Stewart | Botanical Exchange Club Charles Bailey | 30/6/1877 | MANCH |
+ | Calamagrostis stricta | IE, VCH39 Co. Antrim, Lough Neagh | Robert Lloyd Praeger | Botanical Exchange Club of The British Isles Charles Bailey Samuel Alexander Stewart | 7/8/1892 | MANCH |
+ | Calamagrostis stricta | IE, VCH39 Co. Antrim, Lough Neagh | Robert Lloyd Praeger | Botanical Exchange Club of The British Isles Charles Bailey Samuel Alexander Stewart | 7/8/1892 | MANCH |
+ | Calamagrostis stricta | IE, VCH39 Co. Antrim, Toomebridge,Lough Beg | | Charles Bailey James Ward Samuel Alexander Stewart | 8/7/1866 | MANCH |
+ | Calamagrostis stricta | IE, VCH39 Co. Antrim, Toomebridge,Lough Beg | Samuel Alexander Stewart | Charles Bailey | 8/7/1868 | MANCH |
+ | Carex divisa | IE, VCH38 Co. Down | Samuel Alexander Stewart | Botanical Exchange Club Charles Bailey | 6/1876 | MANCH |
+ | Equisetum hyemale x variegatum = E. x trachyodon | IE, VCH39 Co. Antrim, Belfast,Colin Glen | Samuel Alexander Stewart | Botanical Exchange Club | 20/5/1871 | MANCH |
+ | Equisetum hyemale x variegatum = E. x trachyodon | IE, VCH39 Co. Antrim, Belfast,Colin Glen | Samuel Alexander Stewart | Richmond Museum Charles Bailey James Ward | 7/6/1865 | MANCH |
+ | Equisetum hyemale x variegatum = E. x trachyodon | IE, VCH39 Co. Antrim, Belfast,Colin Glen | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Charles Bailey | 29/7/1893 | MANCH |