| Zannichellia polycarpa | IE, VCH38,VCH39, Belfast | Coslett Herbert Waddell Samuel Alexander Stewart | Allan Octavian Hume Coslett Herbert Waddell | 7/1904 | SLBI |
| Zannichellia polycarpa | IE, VCH38,VCH39, Belfast | Coslett Herbert Waddell Samuel Alexander Stewart | Allan Octavian Hume Coslett Herbert Waddell | 7/1904 | SLBI |
| Zannichellia polycarpa | IE, VCH38 Co. Down, Belfast | Coslett Herbert Waddell Samuel Alexander Stewart | Allan Octavian Hume Coslett Herbert Waddell | 7/1904 | SLBI |
| Pilosella lactucella | IE, VCH39 Co. Antrim, Cave Hill | Samuel Alexander Stewart | | 5/7/1902 | ABS |
| 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 |
| Hieracium latobrigorum | IE, VCH39 Co. Antrim, Cranfield | Samuel Alexander Stewart | | 27/7/1899 | ABS |
| Mentha arvensis x aquatica = M. x verticillata | IE, VCH38 Co. Down, Saul | Samuel Alexander Stewart | | 8/1897 | DBN |
| Callitriche hamulata | IE, VCH38 Co. Down, Castlewellan Forest Park | Samuel Alexander Stewart | Watson Botanical Exchange Club Coslett Herbert Waddell Harold Stuart Thompson | 7/6/1897 | BIRM |
| Hieracium orcadense | IE, VCH39 Co. Antrim, Cave Hill, Belfast | Samuel Alexander Stewart | | 21/6/1896 | ABS |
| Potamogeton lucens x gramineus = P. x angustifolius | IE, VCH38 Co. Down, Lagan | Samuel Alexander Stewart | Alfred Fryer Charles Bailey | 12/8/1894 | MANCH |
+ | 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 | Charles Bailey Samuel Alexander Stewart | 10/8/1894 | MANCH |
| Potamogeton perfoliatus x crispus = P. x cooperi | IE, VCH39 Co. Antrim, Templepatrick | Samuel Alexander Stewart | Alfred Fryer Charles Bailey | 10/8/1894 | MANCH |
| Potamogeton perfoliatus x crispus = P. x cooperi | IE, VCH39 Co. Antrim, Templepatrick | Samuel Alexander Stewart | Manchester Museum Charles Bailey | 10/8/1894 | MANCH |
| 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 |
| Potamogeton perfoliatus x crispus = P. x cooperi | IE, VCH39 Co. Antrim, Templepatrick | Samuel Alexander Stewart | | 10/8/1894 | ABS |
| Potamogeton perfoliatus x crispus = P. x cooperi | IE, VCH39 Co. Antrim, Templepatrick | Samuel Alexander Stewart | | 10/8/1894 | SLBI |
| Potamogeton perfoliatus x crispus = P. x cooperi | IE, VCH39 Co. Antrim, Templepatrick | Samuel Alexander Stewart | Alfred Fryer Charles Bailey | 8/1894 | MANCH |
| Potamogeton praelongus | IE, VCH39 Co. Antrim, Sixmile River | Samuel Alexander Stewart | Arthur Bennett | 8/1894 | SLBI |
| Mentha aquatica x spicata = M. x piperita | IE, VCH39 Co. Antrim, Carnmoney | Samuel Alexander Stewart | Science & Art Museum Dublin | 12/8/1893 | DBN |
+ | 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 |
| 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 |
| Potentilla anglica | IE, VCH39 Co. Antrim, Belfast | Samuel Alexander Stewart | | 7/1893 | SLBI |
+ | 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 |
| Hieracium friesii | IE, VCH38 Co. Down, Hilltown | Samuel Alexander Stewart | William Hadden Beeby | 24/7/1891 | SLBI |
| Hieracium gothicoides | IE, VCH38 Co. Down, Hilltown | Samuel Alexander Stewart | | 24/7/1891 | ABS |
| Hieracium stewartii | IE, VCH38 Co. Down, Hilltown | Samuel Alexander Stewart | | 23/7/1891 | ABS |
| Viola | IE, VCH9 Co. Clare, Gort | Samuel Alexander Stewart | Augustin Ley | 22/5/1891 | BIRM |
| Viola persicifolia | IE, VCH9 Co. Clare, Gort | Samuel Alexander Stewart | William Hadden Beeby | 22/5/1891 | SLBI |
| Primula vulgaris x veris = P. x polyantha | IE, VCH16,VCH17, Salt Hill | Samuel Alexander Stewart | | 14/5/1891 | MANCH |
| Sesleria caerulea | IE, Galway, Galway Bay | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Augustin Ley | 5/1891 | BIRM |
| Potamogeton alpinus | IE, VCH38 Co. Down, Newcastle | Samuel Alexander Stewart | Alfred Fryer Charles Bailey | 8/8/1890 | MANCH |
| Hieracium latobrigorum | IE, VCH39 Co. Antrim, Cranfield | Samuel Alexander Stewart | | 27/7/1890 | SLBI |
| Hieracium basalticola | IE, VCH39 Co. Antrim, Sallagh Braes | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles William Hadden Beeby | 15/6/1890 | SLBI |
+ | Hieracium basalticola | IE, VCH39 Co. Antrim, Sallagh Braes | Samuel Alexander Stewart | | 15/6/1890 | BIRM |
| Hieracium basalticola | IE, VCH39 Co. Antrim, Sallagh Braes | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles Frederick Townsend | 15/6/1890 | SLBI |
| Mertensia maritima | IE, VCH38 Co. Down, Glassdrummond | Samuel Alexander Stewart | | 23/6/1889 | SLBI |
+ | Orobanche purpurea | GB, VC10 Isle of Wight, Totland,Lacy's Farm | Samuel Alexander Stewart | Charles Bailey | 7/1888 | MANCH |
| Najas flexilis | IE, VCH16 West Galway, Roundstone | Samuel Alexander Stewart | William Hadden Beeby Arthur Bennett | 15/8/1887 | SLBI |