I’m a big fan of things that smell and taste of vanilla, so it’s good to know that Britain has several wild plants that produce natural chemicals with this quality. A very common species that you have probably walked by growing along riverbanks and other damp areas is Meadowsweet (Filipendula ulmaria). Its frothy cream flowers can be picked and rubbed between your hands to release a powerful vanilla/almond fragrance. This can be used to flavour syrups, make crème caramel, or even, I’m told, to make a Meadowsweet champagne
Traditionally meadowsweet was used to flavour mead, and given that it produces salicylic acid, from which aspirin is synthesised, it is likely to counteract any hangover headaches!
Another vanilla-scented plant is Sweet Woodruff (Galium odoratum), a relative of Cleavers/Goosegrass or Sticky Weed (Galium aparine) ,this plant has the same whorls of leaflets around a central stem, but none of the latter’s sticky characteristics. I was disappointed to read that it is widespread except in a few counties, including Essex and Suffolk. However, I chanced upon some today on a grassy verge at the side of a quiet country road. I’m currently drying it on a straw hat in the sun on a windowsill (if only I had a proper dehydrator…), and it has yet to give off any sign of vanilla or almond scents! Having checked and rechecked various plant identification guides, it seems to be sweet woodruff, as the alternative would be sticky goosegrass. So time will tell – the scent is meant to get stronger as it dries.
It is worth noting that Sweet Woodruff and Meadowsweet both contain chemicals called coumarins, which give the vanilla/almond quality, but can cause headaches in large quantities, but is a strong flavour and only requires small amounts of the plant. More troublesome is the fact that coumarin-containing plants that are left to dry in damp conditions can be infected by Aspergillus mould. This converts coumarin into dicoumarin, a blood thinning agent used to treat high blood pressure. In large doses it can act like the anticoagulant Warfarin, used in rat poison, to cause uncontrolled internal bleeding. Livestock have been killed by eating Aspergillus infected hay containing dicoumarins. However, these are large amounts, and used as a flavouring would be more likely to simply thin the blood. However, clearly this is not worth the risk, so ensure that any sweet woodruff is dried quickly in well ventilated conditions. Source: Irving, M (2009) The forager handbook: A Guide to the Edible Plants of Britain. Ebury Press
UPDATE: Upon drying my suspected Sweet Woodruff, I am forced to conclude that it has no vanilla fragrance! Given the leaf arrangement of whorls on a central stem, I am convinced it is part of the Galium genus, but sadly not the species I had hoped for. It has probably escaped from a garden where a non-native species was planted. You live and learn!