| Carex vulpina | GB, VC15 East Kent, Headcorn | Olga Margaret Stewart | | 25/5/1971 | E |
| Carex vulpinoidea | GB, VC17 Surrey, Tadworth | Olga Margaret Stewart | | 20/9/1989 | E |
| Egeria densa | GB, VC73 Kirkcudbrightshire, New Abbey | Olga Margaret Stewart | | 20/9/1997 | E |
| Elodea callitrichoides | GB, VC13 West Sussex, Chichester | Olga Margaret Stewart | | 21/9/1988 | E |
| Elodea nuttallii | GB, VC60 West Lancashire, Garstang Canal | Olga Margaret Stewart | | 15/9/1987 | E |
| Elodea nuttallii | GB, VC73 Kirkcudbrightshire, Cailsfad Loch | Nicholas F Stewart Olga Margaret Stewart | | 3/8/1993 | E |
| Elodea nuttallii | GB, VC73 Kirkcudbrightshire, Loch Ken | Olga Margaret Stewart | | 22/8/1991 | E |
| Elodea nuttallii | GB, VC73 Kirkcudbrightshire, Loch Ken | Olga Margaret Stewart | | 18/6/1991 | E |
| Elodea nuttallii | GB, VC73 Kirkcudbrightshire, Loch Ken | Olga Margaret Stewart | | 12/9/1996 | E |
| Elodea nuttallii | GB, VC73 Kirkcudbrightshire, Threave House | Nicholas F Stewart Olga Margaret Stewart | | 27/8/1990 | E |
+ | Festuca altissima | GB, VC87 West Perthshire, Ledard Glen | F J Stewart Olga Margaret Stewart | | 25/6/1988 | PTH |
| Festuca arundinacea | GB, VC73 Kirkcudbrightshire, Kirkbean | Olga Margaret Stewart | | 16/6/1975 | K |
| Festuca arundinacea | GB, VC73 Kirkcudbrightshire, Tarff Water | Olga Margaret Stewart | | 22/8/1975 | K |
| Festuca arundinacea | GB, VC81 Berwickshire, Dunglass | Olga Margaret Stewart | | 25/7/1975 | K |
| Hydrilla verticillata | IE, VCH16 West Galway, Renvyle | Olga Margaret Stewart | | 8/9/1991 | E |
| Lagarosiphon major | GB, VC30 Bedfordshire, Arlesley | Olga Margaret Stewart | | 27/6/1971 | E |
+ | Leucojum aestivum | GB, Perthshire, Perth | Olga Margaret Stewart | | 24/5/1982 | PTH |
| Luronium natans | GB, VC40 Shropshire, Montgomery Canal at Llanymynech Bridge | Olga Margaret Stewart | | 25/6/1986 | E |
| Mentha spicata x suaveolens = M. x villosa | GB, VC35 Monmouthshire, Llandogo | Olga Margaret Stewart | | 15/9/1981 | K |
| Mentha spicata x suaveolens = M. x villosa | GB, VC35 Monmouthshire, Newport | Olga Margaret Stewart | | 19/6/1981 | K |
| Mentha suaveolens | GB, VC35 Monmouthshire, Llandogo | Olga Margaret Stewart | | 1981 | K |
| Mentha suaveolens | GB, VC41 Glamorganshire, Barry Docks | Olga Margaret Stewart | | 19/6/1981 | K |
+ | Poa trivialis | GB, VC87 West Perthshire, Doune | Nicholas F Stewart Olga Margaret Stewart | | 24/6/1988 | PTH |
+ | Polypodium interjectum | GB, VC87 West Perthshire, Alva Glen | Olga Margaret Stewart | | 12/7/1988 | PTH |
+ | Potamogeton berchtoldii | GB, VC87 West Perthshire, Cambus Pool | Nicholas F Stewart Olga Margaret Stewart | | 23/6/1988 | PTH |
+ | Potamogeton berchtoldii | GB, VC87 West Perthshire, Doune | Nicholas F Stewart Olga Margaret Stewart | | 24/6/1988 | PTH |
+ | Potamogeton berchtoldii | GB, VC87 West Perthshire, Doune | Nicholas F Stewart Olga Margaret Stewart | | 24/6/1988 | PTH |
+ | Potamogeton berchtoldii | GB, VC87 West Perthshire, Doune | Nicholas F Stewart Olga Margaret Stewart | | 24/6/1988 | PTH |
+ | Potamogeton berchtoldii | GB, VC87 West Perthshire, Doune | Nicholas F Stewart Olga Margaret Stewart | | 24/6/1988 | PTH |
| Potamogeton coloratus x berchtoldii = P. x lanceolatus | IE, VCH9 Co. Clare, Cahir River | Olga Margaret Stewart | | 5/6/1989 | E |
| Potamogeton gramineus | GB, VC73 Kirkcudbrightshire | Olga Margaret Stewart | | 14/9/1974 | E |
| Potamogeton gramineus | GB, VC73 Kirkcudbrightshire, Lochenbreck Loch | Olga Margaret Stewart | | 15/8/1977 | E |
| Potamogeton gramineus | GB, VC96 East Inverness-shire, Loch na Doire-uaine | Mary McCallum Webster Olga Margaret Stewart | | 7/7/1976 | E |
| Potamogeton gramineus | GB, VC112 Shetland, Brindister | Olga Margaret Stewart | | 8/1990 | E |
| Potamogeton lucens | GB, VC33 East Gloucestershire, South Cerney | Olga Margaret Stewart | | 10/8/1970 | E |
| Potamogeton lucens | GB, VC68 North Northumberland, Union Bridge | Olga Margaret Stewart | | 25/7/1975 | E |
| Potamogeton lucens | IE, VCH8 Co. Limerick, Castleconnell | Olga Margaret Stewart | | 9/6/1989 | E |
| Potamogeton lucens x gramineus = P. x angustifolius | GB, VC73 Kirkcudbrightshire, Tarff Water | Olga Margaret Stewart | | 10/9/1988 | E |
| Potamogeton lucens x gramineus = P. x angustifolius | GB, VC80 Roxburghshire, Cauldshields Loch | Olga Margaret Stewart | | 11/9/1974 | E |
| Potamogeton natans | GB, VC108 West Sutherland, Altnaharra | Olga Margaret Stewart | | 27/6/1970 | E |
| Potamogeton natans | GB, VC109 Caithness, Wick | Olga Margaret Stewart | | 23/6/1970 | E |
| Potamogeton nodosus | GB, VC6 North Somerset, Batheaston | Olga Margaret Stewart | | 3/8/1976 | E |
| Potamogeton polygonifolius | GB, VC73 Kirkcudbrightshire, Airie Burn | Olga Margaret Stewart | | 20/7/1974 | E |
| Potamogeton polygonifolius | GB, VC73 Kirkcudbrightshire, Duimhumphrey | Nicholas F Stewart Olga Margaret Stewart | | 3/7/1988 | E |
| Potamogeton polygonifolius | GB, VC104 North Ebudes, Dunvegan | Olga Margaret Stewart | | 23/6/1975 | E |
| Potamogeton polygonifolius | GB, VC108 West Sutherland, Altnaharra | Olga Margaret Stewart | | 27/6/1970 | E |
+ | Ranunculus fluitans | GB, VC87 West Perthshire, Tullibody | G Graham Nicholas F Stewart Olga Margaret Stewart | | 27/8/1987 | PTH |
+ | Ranunculus sardous | GB, VC87 West Perthshire, Cambus Pool | Nicholas F Stewart Olga Margaret Stewart | | 23/6/1988 | PTH |
| Taraxacum haworthianum | GB, VC73 Kirkcudbrightshire, Kirkandrew | Olga Margaret Stewart | | 20/5/1978 | E |