Herb of the month: a tribute to Tansy

Last update: 31.08.17 First posted: 17.08.17 by in

Tansy seems to be everywhere this summer – certainly in the apothecary garden! Last week, I spent a long afternoon with Mel the lovely volunteer and Toto the apothecary dog, pulling up the tansy that had overgrown and was crowding out the more delicate herbs around it. This was before I learned that tansy can cause contact dermatitis in some people…
Luckily, I seem to be immune to the volatile essential oil in its leaves, but I would like to start this blog post with a warning: if you want to pick tansy, start by picking just one leaf, and leave it for a few hours to see if a reaction develops. And be very, very careful if you plan to take this herb internally. It can be toxic.

Tansy is a time-honoured insect repellent, both internally and externally. In the apothecary garden, you will find it in the strewing herbs bed (and everywhere else at the moment, while I’m in the process of pulling it up!). It was mentioned by Thomas Tusser in a list of strewing herbs from 1557 and would certainly have been used in Tudor households. The dried leaves and flowers can be added to moth-repellent sachets or pot-pourri mixes, or simply sprinkled on windowsills to keep flies away. The leaves in particular have a bitter, camphor-like scent, similar to mugwort but stronger.

Its insect repellent properties make tansy a good companion plant in some controlled cases: in the U.S., studies show it can reduce the population of potato beetles by 6% – 100%. But it spreads quickly by self-seeding and spreading its rhizomes under the earth, and needs careful controlling to prevent it taking over.

Tansy also has a long history of use as an internal medicine for parasites and worms: in medicinal terms, it is an ‘anthelmintic’. A strong infusion of the leaves was drunk to flush out internal parasites, or used as a wash to ward off external parasites. The juice and chopped leaves of the plants were traditionally mixed with eggs to make tansy cakes – tansy omelettes, really – to eat at Easter, to flush out all the parasites supposedly picked up during Lent. One more word of caution, though: while trying tansy cakes in the programme ‘The Supersizers Go… Restoration!’ on the BBC, presenter Sue Perkins contracted tansy poisoning!

As a medicine, tansy was traditionally used to treat rheumatism, fevers, and digestive problems, and to bring on menstruation, but all of these ailments can be treated much more safely with other herbs.

The name itself comes from the Greek word athanaton, meaning ‘immortal’ – possibly because its yellow flowers last for so long without wilting, and possibly because its parasite-repelling properties make it an excellent embalming herb. It has a long association with death and mourning, particularly in the U.S. The dried leaves and flowers were packed into coffins, wrapped in funeral winding sheets, and woven into wreaths for the dead. In 1668 the first president of Harvard University, Henry Dunster, was buried in a coffin packed with tansy; when the grave was moved nearly 200 years later, the tansy was found to have kept its shape and fragrance.

According to American botanist Judith Sumner, tansy was traditionally used in Yorkshire, too, to flavour the biscuits served at funerals – if anyone reading this blog can remember this tradition, please get in touch, because it would be lovely to have a local source for this folkloric tidbit.

Once I get on top of it, there will be quite a bit less tansy in the apothecary garden. It is a beautiful, vigorous plant with a fascinating history, but one to be approached with caution.

Sources:

Bartram, Encyclopedia of Herbal Medicine
Grieve, A Modern Herbal
Sumner, American Household Botany
‘Common Tansy’: http://msuextension.org/publications/AgandNaturalResources/MT199911AG.pdf
‘The Supersizers Go… Restoration!’ –
Part 1: https://www.youtube.com/watch?v=TCfx98Ei5lM
[watch from 8:44 for tansy recipe]
Part 2: https://www.youtube.com/watch?v=fCiBMDhs5p0
[watch from 6:00 for tansy poisoning!]

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