+ | Equisetum hyemale x variegatum = E. x trachyodon | IE, VCH39 Co. Antrim, Colin Glen | Samuel Alexander Stewart | | 22/6/1879 | BIRM |
| Equisetum hyemale x variegatum = E. x trachyodon | IE, VCH39 Co. Antrim, Colin Glen | Samuel Alexander Stewart | | 1/7/1872 | BON |
| Hieracium orcadense | IE, VCH39 Co. Antrim, Cave Hill, Belfast | Samuel Alexander Stewart | | 21/6/1896 | ABS |
| Orobanche alba | IE, VCH39 Co. Antrim, Cave Hill, Belfast | Samuel Alexander Stewart | Augustin Ley | 8/7/1871 | BIRM |
| Alchemilla filicaulis | IE, VCH39 Co. Antrim, Cave Hill | Samuel Alexander Stewart | William Hunt Painter | 5/7/1886 | ABS |
| Pilosella lactucella | IE, VCH39 Co. Antrim, Cave Hill | Samuel Alexander Stewart | | 5/7/1902 | ABS |
| 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 |
| Potamogeton perfoliatus | IE, VCH39 Co. Antrim, Bushmills | Samuel Alexander Stewart | Richmond Museum Charles Bailey | 7/1866 | MANCH |
| Carex distans | IE, VCH39 Co. Antrim, Black Head | Samuel Alexander Stewart | | 29/6/1872 | BON |
+ | Stratiotes aloides | IE, VCH39 Co. Antrim, Belfast,Springfield | Samuel Alexander Stewart | Richmond Museum Charles Bailey James Ward | 3/7/1865 | MANCH |
+ | Potamogeton praelongus | IE, VCH39 Co. Antrim, Belfast,Lagan Canal | Samuel Alexander Stewart | Charles Bailey James Ward | 2/7/1866 | MANCH |
+ | Potamogeton praelongus | IE, VCH39 Co. Antrim, Belfast,Lagan Canal | Samuel Alexander Stewart | Alfred Fryer Charles Bailey | 23/6/1873 | 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 |
| Equisetum hyemale x variegatum = E. x trachyodon | IE, VCH39 Co. Antrim, Belfast,Colin Glen | Samuel Alexander Stewart | Harold Stuart Thompson | 22/6/1879 | BIRM |
| Potamogeton alpinus | IE, VCH39 Co. Antrim, Belfast | Samuel Alexander Stewart | Richmond Museum Charles Bailey James Ward | 2/7/1866 | MANCH |
| Potentilla anglica | IE, VCH39 Co. Antrim, Belfast | Samuel Alexander Stewart | | 7/1893 | SLBI |
| 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 |
| Viola tricolor subsp. curtisii | IE, VCH39 Co. Antrim, Antrim | Samuel Alexander Stewart | Botanical Exchange Club of The British Isles William Hadden Beeby John Gilbert Baker | 25/6/1886 | SLBI |
| Mentha arvensis x aquatica = M. x verticillata | IE, VCH38 Co. Down, Saul | Samuel Alexander Stewart | | 8/1897 | DBN |
+ | Galeopsis versicolor | IE, VCH38 Co. Down, Rathmullan | Samuel Alexander Stewart | Charles Bailey James Ward | 26/7/1866 | MANCH |
| Potamogeton alpinus | IE, VCH38 Co. Down, Newcastle | Samuel Alexander Stewart | Alfred Fryer Charles Bailey | 8/8/1890 | MANCH |
| Lobelia dortmanna | IE, VCH38 Co. Down, Mourne Mountains | Samuel Alexander Stewart | Richmond Museum Charles Bailey James Ward | 7/9/1865 | MANCH |
| Potamogeton lucens x gramineus = P. x angustifolius | IE, VCH38 Co. Down, Lagan | Samuel Alexander Stewart | Alfred Fryer Charles Bailey | 12/8/1894 | MANCH |
| Rosa spinosissima x canina = R. x hibernica | IE, VCH38 Co. Down, Holywood | Samuel Alexander Stewart | Frederick Arnold Lees | 6/1871 | SLBI |
| 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 |
| Lavatera arborea | IE, VCH38 Co. Down, Groomsport | Samuel Alexander Stewart | William Hadden Beeby | 15/7/1871 | SLBI |
| Atriplex laciniata | IE, VCH38 Co. Down, Groomport | Samuel Alexander Stewart | Augustin Ley | 10/9/1870 | BIRM |
| Mertensia maritima | IE, VCH38 Co. Down, Glassdrummond | Samuel Alexander Stewart | | 23/6/1889 | SLBI |
| Valerianella carinata | IE, VCH38 Co. Down, Dundonald | Samuel Alexander Stewart | Augustin Ley | 19/6/1877 | BIRM |
+ | Apium nodiflorum x inundatum = A. x moorei | IE, VCH38 Co. Down, Downpatrick,Quoile | Samuel Alexander Stewart | Charles Bailey | 16/9/1886 | MANCH |
| 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 |
| Apium inundatum | IE, VCH38 Co. Down, Downpatrick | Samuel Alexander Stewart | | 16/9/1886 | SLBI |
| 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 |