Water Mint, Mentha aquatica, on Beeston Common, Norfolk (August 2019).

One of my favourite smells is Water Mint, Mentha aquatica. The plant has a clear, pure minty freshness that soothes and clears the nose at the same time. I can’t resist touching Water Mint leaves when I walk past, but earlier in the season the scent can come as a pleasant surprise, when you tread on it in short, damp turf near a stream and unwittingly bruise its stems and leaves (note 1).

Last Thursday we made a brief visit to Beeston Common near Sheringham in North Norfolk. The wetter areas are a mass of flowers at the moment, and stands of Wild Angelica (Angelica sylvestris), Common Fleabane (Pulicaria dysenterica) , Tansy (Tanacetum vulgare) and Water Mint (Mentha aquatica) were attracting lots of insects, including butterflies, hoverflies and solitary bees. The dense stands of Water Mint were especially spectacular, with the plants growing over 30 centimetres (one foot) tall, topped by dense heads of small lilac-pink flowers with one or two further whorls of flowers beneath.

Water Mint is in flower somewhere in the UK from July to October, but the peak of flowering will depend on the year’s weather and where the plant is growing: late August to mid September is usually best here in Norfolk. To help you recognise the plant, there are great photos of Water Mint on the Wild Flower Finder, Nature Gate, Nature Spot and First Nature websites.

The plant’s scientific name, Mentha aquatica, literally means “Water Mint” (note 2). It is a hardy perennial plant (note 3) which spreads by rhizomes, which sometimes break off to create new plants. It grows in wet places such as marshes, fens, ditches, ponds and the edges of rivers, in dune-slacks and wet woods. Water Mint is a British native and is very widely distributed, so in most of the British Isles you won’t need to travel far to find your nearest patch. Mine is only yards away from there I am writing this, in a pond in the back garden.

Like other mints and many culinary herbs (such as Sage, Marjoram, Thyme and Hyssop) Water Mint is a member of the Lamiaceae, a family of plants with a cosmopolitan distribution and around 7,000 species in over 230 genera. The genus Mentha is distributed across Europe, Africa, Asia, Australia and North America and there are between 13 and 24 species, plus many hybrids (note 4).

As well as the British Isles, Water Mint is native to much of Europe and parts of north-west Africa and western Asia. It has been introduced (deliberately) to North and South America, Australia and some Atlantic islands. 

Mints are useful plants and the Plants For A Future website gives a number of uses for Water Mint. The leaves are edible raw or cooked but are very pungent, so a little goes a long way. They can be used, sparingly, in salads or cooked dishes, though “the leaves are too pungent for most people to use as a flavouring“.

One of the best uses of Water Mint is to make a mint tea from the leaves. Mint tea is very refreshing and a pleasant caffeine-free drink. The tea also has a number of possible medicinal properties and it has traditionally been used in the treatment of fevers, headaches, digestive disorders and various minor ailments. On his blog, Paul Kirtley suggests using Water Mint to calm digestive disorders, flatulence and nausea and he found that eating some eased his stomach cramps after a bout of food poisoning.

The Gardening Know How website suggests using Water Mint externally as a balm for sore muscles or to help clean wounds. Water Mint contain menthol, which has known antibacterial properties and triggers cooling receptors when applied to the skin.

Other volatile compounds in Water Mint include menthone, carvone, limonene, linalool, menthyl acetate, piperitone, and pulegone (note 5). Some of these, including pulegone (also found in Catmint) and menthol are toxic in large quantities but eating a bit of Water Mint now and then is not going to cause you any harm.

The Plants For a Future website has includes a warning: “Although no records of toxicity have been seen for this species, large quantities of some members of this genus, especially when taken in the form of the extracted essential oil, can cause abortions so some caution is advised”. The warning applies particularly to Pennyroyal, Mentha pulegium (note 6). Pennyroyal oil contains very high levels of pulegone (80% to 92%), whereas Water Mint oil has much lower levels (around 15%, note 5).

Water Mint was sometimes strewn on floors to give a scent of mint and it can be used to scent a room in potpourri, in aromatherapy or added to herb pillows or used fresh or dried in herbal baths. The cut foliage is said repel mice and flies as well.

Water Mint is abundant enough to pick from the wild but also very easy to grow in the garden in damp soil or in a pond, though it spreads fast and it usually needs to be kept in control. I let mine grow in the open water of the pond and remove clumps of it from time to time to prevent it from taking over. It can be grown from seed but the easiest option is to find someone near you who already grows it and ask for some. If you have some Water Mint growing wild near where you live, you can cut a few stems and place them in a vase of water and they will root within a few weeks (note 7).

My own favourite use of Water Mint is in Watermint Sorbet. The recipe comes from John Wright’s book “Hedgerow” (River Cottage Handbook No. 7, Bloomsbury, 2010). For the original recipe, you’ll need to buy the book (and I suggest that you do, as it is very good) but the Noémie’s kitchen website gives a slightly modified version (called Lemon and watermint sorbet). I tend to use slightly less sugar than in the recipes. The result is a lemon sorbet with a refreshingly minty tang and often a slight pink colour.

I find the flavour of the Water Mint varies as summer progresses. Herbs, including Water Mint, have the best flavour when they are gathered just before flowering, but for the sorbet I quite like the added complexity of flavour once the plant has started to flower.

Notes

Note 1 – Unfortunately the limits of the internet prevent me from sharing the smell of Water Mint with you, so you will need to go and find your own patch to sniff.

People have tried to combine smells with pictures several times, not via the internet but by releasing smells (such as tobacco smoke) into cinemas at appropriate points during a film. This has been tried several times, but never very successfully, under the names “Smell-O-Vision”, “Smellorama”, “Scentovision” and “AromaRama”. I recommend Wikipedia’s “Smell-O-Vision” page if you want to know more. I don’t think Water Mint’s smell has ever been used in this way, which is a pity.

Note 2 – The genus Mentha is named after the naiad Minthe (also spelt Menthe, Mintha or Mentha) in Greek mythology. Minthe fancied the Greek god Hades and tried to seduce him but Persephone (daughter of Zeus and queen of the underworld) transformed her into a sweet-smelling mint plant. (Allegedly.)

Note 3 – The Gardening Know How website says it is hardy in USDA zones 8 to 11. In Finland, Water Mint is only native in the milder Åland Islands but it has escaped from cultivation elsewhere.

Note 4 – Water Mint is one of the parents of Peppermint (Mentha x piperita). This is a a hybrid mint formed by a natural cross between Mentha aquatica and Spearmint (Mentha spicata). Peppermint is grown as a commercial crop and the world production of peppermint in 2014 was 92,296 tonnes, largely in Morocco (92% of the total). Peppermint leaves are used to make herb teas and the plant’s essential oil is used to flavour confectionery and toothpaste.

Note 5 – For details of the compounds found in Water Mint in Tunisia, see Wissal Dhifi , Mariem Litaiem , Nahida Jelali , Naceur Hamdi and Wissem Mnif (2011) –  Identification of A New Chemotype of the Plant Mentha aquatica Grown in Tunisia: Chemical Composition, Antioxidant and Biological activities of its Essential Oil, Jeobp 14 (3) pp 320 – 328.

Note 6 – Pennyroyal, Mentha pulegium, is a low and spreading type of mint with pretty flowers and a very intense scent, which is sometimes grown as a garden herb. It was formerly used as a medicinal herb. Two of its main uses were as a contraceptive and to trigger abortions, but its use is very risky and large or concentrated doses of Pennyroyal have caused the deaths of several pregnant women over the years.

Note 7 – It is illegal to uproot wild flowers without the landowner’s permission (under the Wildlife and Countryside Act, 1981 in Britain and the Wildlife (Northern Ireland) Order, 1985, in Northern Ireland.) See the Wild Flower Society’s Code of Conduct for the conservation and enjoyment of wild plants.