| Carex arenaria | IE, VCH38 Co. Down, Co. Down | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 6/1876 | BIRM |
| Apium nodiflorum x inundatum = A. x moorei | IE, VCH38 Co. Down, Downpatrick,Quoile | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 7/1880 | BIRM |
| Valerianella carinata | IE, VCH38 Co. Down, Dundonald | Samuel Alexander Stewart | Augustin Ley | 19/6/1877 | BIRM |
| Atriplex laciniata | IE, VCH38 Co. Down, Groomport | Samuel Alexander Stewart | Augustin Ley | 10/9/1870 | 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 |
| 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 |
| 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 |
| Polygala vulgaris | IE, VCH28 Co. Sligo, Benbulben | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Edward Francis Linton | 16/7/1879 | SLBI |
| Carex arenaria | IE, VCH38 Co. Down | Samuel Alexander Stewart | Edward Francis Linton | 6/1876 | BM |
| Pilosella peleteriana | IE, VCH39 Co. Antrim, Core Hill, Belfast Cultivated | Coslett Herbert Waddell | Botanical Exchange Club of The British Isles Coslett Herbert Waddell Edward Francis Linton Samuel Alexander Stewart | 8/1900 | ABS |
| Carex spicata | IE, VCH39 Co. Antrim, Greencastle | Samuel Alexander Stewart | Edward Francis Linton | 19/6/1873 | BM |
+ | Euphorbia hyberna | IE, VCH2 North Kerry, Killarney,Cromagloun (Cromaglan) | Samuel Alexander Stewart | Coslett Herbert Waddell Elizabeth Anne Lomax | 18/6/1885 | MANCH |
| Saxifraga hirsuta | IE, Kerry, Cromaglan Mountain | Samuel Alexander Stewart | Samuel Alexander Stewart William Hunt Painter | 18/6/1885 | ABS |
| Alchemilla filicaulis | IE, VCH39 Co. Antrim, Cave Hill | Samuel Alexander Stewart | William Hunt Painter | 5/7/1886 | ABS |
| Polygala vulgaris | IE, VCH28 Co. Sligo, Benbulben | Samuel Alexander Stewart | Reginald Wiliam Scully | 3/8/1883 | SLBI |
| Arenaria ciliata | IE, VCH28 Co. Sligo, Kings Mountain | Samuel Alexander Stewart | Reginald Wiliam Scully | 18/7/1879 | SLBI |
| Euphorbia hyberna | IE, Kerry, Cromaglan Mountain | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles | 15/6/1885 | ABS |
| Euphorbia hyberna | IE, Kerry, Cromaglan Mountain | Samuel Alexander Stewart | | 18/6/1885 | ABS |
| Arctostaphylos uva-ursi | IE, VCH9 Co. Clare, Black Head | Samuel Alexander Stewart | Robert Large Baker | 5/1876 | BIRM |
| Dryas octopetala | IE, VCH9 Co. Clare, Black Head | Samuel Alexander Stewart | | 12/5/1876 | SLBI |
| Apium nodiflorum x inundatum = A. x moorei | IE, VCH16 West Galway, Doonpatrick | Samuel Alexander Stewart | Samuel Alexander Stewart | 7/1880 | BIRM |
| Eriocaulon aquaticum | IE, VCH16 West Galway, Roundstone | Samuel Alexander Stewart | | 29/7/1867 | BON |
| Daboecia cantabrica | IE, Mayo, Uggool | Samuel Alexander Stewart | Robert Large Baker | 19/8/1877 | BIRM |
| Dryas octopetala | IE, VCH28 Co. Sligo, Benbulben | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles | 16/7/1879 | SLBI |
| Arenaria ciliata | IE, VCH28 Co. Sligo, Kings Mountain | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Allan Octavian Hume | 18/7/1879 | SLBI |
| Apium inundatum | IE, VCH38 Co. Down, Downpatrick | Samuel Alexander Stewart | | 16/9/1886 | SLBI |
| Mertensia maritima | IE, VCH38 Co. Down, Glassdrummond | Samuel Alexander Stewart | | 23/6/1889 | SLBI |
| Hieracium gothicoides | IE, VCH38 Co. Down, Hilltown | Samuel Alexander Stewart | | 24/7/1891 | ABS |
| Mentha arvensis x aquatica = M. x verticillata | IE, VCH38 Co. Down, Saul | Samuel Alexander Stewart | | 8/1897 | DBN |
| Rosa spinosissima x canina = R. x hibernica | IE, VCH39 Co. Antrim, Belfast | Samuel Alexander Stewart | | 12/7/1875 | SLBI |
| Zannichellia palustris | IE, VCH39 Co. Antrim, Belfast | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Samuel Alexander Stewart | 12/8/1878 | ABS |
| Potentilla anglica | IE, VCH39 Co. Antrim, Belfast | Samuel Alexander Stewart | | 7/1893 | SLBI |
+ | Stratiotes aloides | IE, VCH39 Co. Antrim, Belfast,Springfield | Samuel Alexander Stewart | Richmond Museum Charles Bailey James Ward | 3/7/1865 | MANCH |
| Carex distans | IE, VCH39 Co. Antrim, Black Head | Samuel Alexander Stewart | | 29/6/1872 | BON |
| Mentha aquatica x spicata = M. x piperita | IE, VCH39 Co. Antrim, Carnmoney | Samuel Alexander Stewart | Science & Art Museum Dublin | 14/9/1872 | DBN |