| Atriplex laciniata | IE, VCH38 Co. Down, Groomport | Samuel Alexander Stewart | Augustin Ley | 10/9/1870 | BIRM |
| Equisetum hyemale x variegatum = E. x trachyodon | IE, VCH39 Co. Antrim, Belfast,Colin Glen | Samuel Alexander Stewart | Harold Stuart Thompson | 22/6/1879 | BIRM |
| Orobanche alba | IE, VCH39 Co. Antrim, Cave Hill, Belfast | Samuel Alexander Stewart | Augustin Ley | 8/7/1871 | BIRM |
| Equisetum hyemale x variegatum = E. x trachyodon | IE, VCH39 Co. Antrim, Colin Glen | Samuel Alexander Stewart | Augustin Ley | 1/7/1872 | BIRM |
| Equisetum hyemale x variegatum = E. x trachyodon | IE, VCH39 Co. Antrim, Colin Glen | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 29/7/1893 | BIRM |
+ | Equisetum hyemale x variegatum = E. x trachyodon | IE, VCH39 Co. Antrim, Colin Glen | Samuel Alexander Stewart | | 22/6/1879 | BIRM |
| Salix viminalis x caprea = S. x smithiana | IE, VCH39 Co. Antrim, Kilroot | Samuel Alexander Stewart | George Stephen West | 5/1868 | 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 |
| Carex elata | IE, VCH39 Co. Antrim, Portmore | Samuel Alexander Stewart | Augustin Ley | 20/6/1872 | BIRM |
| Bidens cernua | IE, VCH39 Co. Antrim, Portmore Lough | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 27/8/1886 | BIRM |
+ | Hieracium basalticola | IE, VCH39 Co. Antrim, Sallagh Braes | Samuel Alexander Stewart | | 15/6/1890 | 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 |
| Barbarea intermedia | IE, VCH39 Co. Antrim, Whitewell, Belfast | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 15/6/1879 | 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 remota | IE, VCH39 Co. Antrim, Cushendall | Samuel Alexander Stewart | | 28/6/1866 | BM |
| Carex dioica | IE, VCH39 Co. Antrim, Divis Hill | Samuel Alexander Stewart | | 12/5/1866 | BM |
| Carex spicata | IE, VCH39 Co. Antrim, Greencastle | Samuel Alexander Stewart | Edward Francis Linton | 19/6/1873 | BM |
| Eriocaulon aquaticum | IE, VCH16 West Galway, Roundstone | Samuel Alexander Stewart | | 29/7/1867 | BON |
| 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 |
| Mentha arvensis x aquatica = M. x verticillata | IE, VCH38 Co. Down, Saul | Samuel Alexander Stewart | | 8/1897 | DBN |
| 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 |
| Scrophularia auriculata | IE, VCH39 Co. Antrim, Four Mile Burn | Samuel Alexander Stewart | Alexander Somerville | 22/7/1883 | E |
+ | Orobanche purpurea | GB, VC10 Isle of Wight, Totland,Lacy's Farm | Samuel Alexander Stewart | Charles Bailey | 7/1888 | MANCH |
| Primula vulgaris x veris = P. x polyantha | IE, VCH16,VCH17, Salt Hill | Samuel Alexander Stewart | | 14/5/1891 | MANCH |
+ | Euphorbia hyberna | IE, VCH2 North Kerry, Killarney,Cromagloun (Cromaglan) | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Charles Bailey | 15/6/1885 | MANCH |
+ | Euphorbia hyberna | IE, VCH2 North Kerry, Killarney,Cromagloun (Cromaglan) | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Charles Bailey | 15/6/1885 | MANCH |
+ | Euphorbia hyberna | IE, VCH2 North Kerry, Killarney,Cromagloun (Cromaglan) | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Charles Bailey | 15/6/1885 | MANCH |
+ | Euphorbia hyberna | IE, VCH2 North Kerry, Killarney,Cromagloun (Cromaglan) | Samuel Alexander Stewart | Coslett Herbert Waddell Elizabeth Anne Lomax | 18/6/1885 | MANCH |
+ | Groenlandia densa | IE, VCH8 Co. Limerick, Ferry Bridge | Samuel Alexander Stewart | Alfred Fryer Charles Bailey | 3/8/1886 | MANCH |
| Saxifraga umbrosa x spathularis = S. x urbium | IE, VCH16 West Galway, Connemara | Samuel Alexander Stewart | Charles Bailey | 10/5/1876 | MANCH |
+ | Eriocaulon aquaticum | IE, VCH16 West Galway, Connemara,Roundstone | Samuel Alexander Stewart | Charles Bailey | 29/7/1867 | MANCH |
+ | Hymenophyllum wilsonii | IE, VCH16 West Galway, Twelve Pins,Bengower | Samuel Alexander Stewart | Charles Bailey | 10/5/1876 | MANCH |
| Potamogeton coloratus | IE, VCH28 Co. Sligo, Coolgagh Loch | Samuel Alexander Stewart | Alfred Fryer Charles Bailey | 4/8/1883 | MANCH |
+ | Carex divisa | IE, VCH38 Co. Down | Samuel Alexander Stewart | Botanical Exchange Club Charles Bailey | 6/1876 | MANCH |
| Potamogeton obtusifolius | IE, VCH38 Co. Down, Comber | Samuel Alexander Stewart | Alfred Fryer Charles Bailey | 27/7/1884 | MANCH |