| Salix viminalis x caprea = S. x smithiana | GB, VC52 Anglesey, Llyn Maelog | Christopher David Preston Nicholas F Stewart | | 27/8/1989 | CGE |
| Salix viminalis x caprea = S. x smithiana | IE, VCH35 West Donegal, Carrowkeel | Christopher David Preston Nicholas F Stewart | | 25/8/1989 | CGE |
| Salix viminalis x caprea = S. x smithiana | IE, VCH35 West Donegal, Dunglow Lough | Christopher David Preston Nicholas F Stewart S D Webster | | 22/8/1989 | CGE |
| Salix viminalis x caprea = S. x smithiana | IE, VCH35 West Donegal, Lough Meela | Christopher David Preston Nicholas F Stewart S D Webster | | 23/8/1989 | CGE |
| Mentha arvensis x aquatica = M. x verticillata | IE, VCH12 Co. Wexford, Kildavin Bridge | Nicholas F Stewart | | 15/9/1991 | DBN |
| Mentha arvensis x aquatica x spicata = M. x smithiana | IE, VCH12 Co. Wexford, Screen Hills | Nicholas F Stewart Rosemary Fitzgerald | | 14/9/1990 | DBN |
| Carex acutiformis | GB, VC82 East Lothian, Windy Mains | Nicholas F Stewart | | 6/1982 | E |
| Carex disticha | IE, VCH39 Co. Antrim, Shanes Castle | Nicholas F Stewart | Alexander Somerville | 7/7/1891 | E |
| Carex spicata | GB, VC29 Cambridgeshire, Dry Drayton | Nicholas F Stewart | | 20/6/1979 | E |
| Elodea nuttallii | GB, VC73 Kirkcudbrightshire, Cailsfad Loch | Nicholas F Stewart Olga Margaret Stewart | | 3/8/1993 | E |
| Elodea nuttallii | GB, VC73 Kirkcudbrightshire, Threave House | Nicholas F Stewart Olga Margaret Stewart | | 27/8/1990 | E |
| Elodea nuttallii | GB, VC86 Stirlingshire, Castlecary | Nicholas F Stewart | | 22/9/1983 | E |
| Potamogeton coloratus | GB, VC103 Mid Ebudes, Coll Island | Christopher David Preston Nicholas F Stewart | Cambridge University | 7/7/1989 | E |
| Potamogeton coloratus x gramineus = P. x billupsii | GB, VC110 Outer Hebrides, Loch na Liana Mòire | Christopher David Preston Helen E Stace J H Bratton Nicholas F Stewart S D Webster | Cambridge University | 10/9/1987 | E |
| Potamogeton gramineus | GB, VC29 Cambridgeshire, Block Fen, Chatteris | Christopher David Preston Nicholas F Stewart | Cambridge University | 28/7/1988 | E |
| Potamogeton gramineus | GB, VC103 Mid Ebudes, Loch Ballyhaugh | Christopher David Preston Nicholas F Stewart | Cambridge University | 6/7/1989 | E |
| Potamogeton gramineus | GB, VC110 Outer Hebrides, An Lige Mor | Christopher David Preston Helen E Stace Nicholas F Stewart S Webster | Cambridge University | 8/9/1987 | E |
| Potamogeton gramineus | GB, VC110 Outer Hebrides, Harris | John J Day Nicholas F Stewart | Loch Survey Herbarium | 17/9/1995 | E |
| Potamogeton gramineus | GB, VC110 Outer Hebrides, Lewis | John J Day Nicholas F Stewart | Loch Survey Herbarium | 16/9/1995 | E |
| Potamogeton gramineus | GB, VC110 Outer Hebrides, Loch Dalbeg | John J Day Nicholas F Stewart | Loch Survey Herbarium | 16/9/1995 | E |
| Potamogeton gramineus | GB, VC110 Outer Hebrides, Loch Mor Barvas | John J Day Nicholas F Stewart | Loch Survey Herbarium | 23/9/1985 | E |
| Potamogeton gramineus | GB, VC110 Outer Hebrides, Loch Nighean Fhailtean | John J Day Nicholas F Stewart | Loch Survey Herbarium | 27/9/1995 | E |
| Potamogeton lucens x gramineus = P. x angustifolius | GB, VC101 Kintyre, Aucha Lochy | Christopher David Preston Nicholas F Stewart | Cambridge University | 19/6/1988 | E |
| Potamogeton lucens x gramineus = P. x angustifolius | GB, VC101 Kintyre, Aucha Lochy | Christopher David Preston Nicholas F Stewart | Cambridge University | 19/6/1988 | E |
| Potamogeton lucens x gramineus = P. x angustifolius | GB, VC101 Kintyre, Loch Barnluasgan | Christopher David Preston M G B Hughes Nicholas F Stewart | Cambridge University | 20/6/1988 | E |
| Potamogeton lucens x gramineus = P. x angustifolius | GB, VC101 Kintyre, Loch Coille-Bharr | Christopher David Preston M G B Hughes Nicholas F Stewart | Cambridge University | 20/6/1988 | E |
| Potamogeton lucens x gramineus = P. x zizii | GB, VC101 Kintyre, Aucha Lochy | Christopher David Preston Nicholas F Stewart | Cambridge University | 19/6/1988 | E |
| Potamogeton polygonifolius | GB, VC73 Kirkcudbrightshire, Duimhumphrey | Nicholas F Stewart Olga Margaret Stewart | | 3/7/1988 | E |
| Potamogeton polygonifolius | GB, VC101 Kintyre, Island of Danna | Christopher David Preston M G B Hughes Nicholas F Stewart | Cambridge University | 20/6/1988 | E |
| Potamogeton polygonifolius | GB, VC101 Kintyre, Tangy Loch | Christopher David Preston Nicholas F Stewart | Cambridge University | 19/6/1988 | E |
+ | Acorus calamus | GB, VC87 West Perthshire, Blair Drummond | Nicholas F Stewart Olga Margaret Stewart | | 17/6/1988 | PTH |
+ | Agrostis vinealis | GB, VC87 West Perthshire, Balquharn Glen | Nicholas F Stewart | | 4/7/1988 | PTH |
+ | Amsinckia micrantha | GB, VC87 West Perthshire, Middleton Farm | Nicholas F Stewart | | 14/6/1980 | PTH |
+ | Amsinckia micrantha | GB, VC89 East Perthshire, Stormont Loch | Nicholas F Stewart | | 21/6/1980 | PTH |
+ | Barbarea intermedia | GB, VC87 West Perthshire, Powmill | Helen E Stace Nicholas F Stewart | | 5/5/1984 | PTH |
+ | Bolboschoenus maritimus | GB, VC87 West Perthshire, Clackmannan | Helen E Stace Nicholas F Stewart | | 25/9/1986 | PTH |
+ | Calamagrostis epigejos | GB, VC87 West Perthshire, Blair Castle | Helen E Stace Nicholas F Stewart | | 30/9/1984 | PTH |
+ | Calamagrostis epigejos | GB, VC87 West Perthshire, Stirling | Nicholas F Stewart Richard E Thomas | | 24/5/1983 | PTH |
+ | Carex acutiformis | GB, VC87 West Perthshire, Balquhidder | Helen E Stace Nicholas F Stewart | | 1982 | PTH |
+ | Carex acutiformis | GB, VC87 West Perthshire, Dollar | Nicholas F Stewart | | 14/6/1988 | PTH |