Tim EntwisleWormwood for fever not flavour

The main thing you’ll taste in the green liqueur absinthe is a licorice flavour, thanks to anise, not the mystical wormwood ingredient. But there is some wormwood, Artemisia absinthium, in it still. Vermouth also has a little wormwood, added originally to wine to disguise the less attractive qualities of cheap alcohol (according to my Drunken Botanist companion book, by Amy Stewart).

Artemisia absinthium. Photo Matt Lavin from Bozeman, Montana, USA

Artemisia absinthium. Photo Matt Lavin from Bozeman, Montana, USA

Although (again thanks to Amy Stewart) the active and potentially dangerous chemical thujone is present in old and new absinthe, and regulated in some countries, plants like Sage have even higher doses. The wild nights and hallucinations attributed to absinthe are more likely due to the wildly high alcohol content of the drink – about twice as strong as gin.

A few different species of Artemisia are used in alcoholic drinks, collectively called génépi after one of the other species used, Artemisia genipi. Artemisia absinthium is a European plant but one that has established itself nicely in places like Mexico.

Artemisia abrotanum

Artemisia abrotanum

That’s the wild and crazy side of wormwood. There are about 400 hundred species of Artemisia but for many of us we know the genus by a handful of tough and persistent hedge species.

Powis castle, Wales

Powis castle, Wales

Most of the wormwoods I could track down in the Royal Botanic Gardens were Artemisia arborescens but we have plenty of other species and cultivars. Artemisia ‘Powis Castle’ (an excuse to include this picture taken on my visit to the Welsh Powis Castle in 2012). I couldn’t find it, but we have records of it from the Grey Garden (near the Temple of the Winds) and the Herb Garden – it’s probably pruned back or covered by some other grey or herby species.

Artemisia annua

“Least-impressive-looking” Artemisia annua

I read recently (Landscape Architecture Magazine, October 2013) about Artemisia annua, described by the author Constance Casey as “perhaps the least-impressive-looking of the several hundred Artemisia species”. So it wasn’t in the magazine for its landscape qualities!

It’s profile links back to my November post about quinine and malaria. The chemical responsible for some of the bitter attributes of the Artemisia leaves, and part of its weaponry against nibbling bugs, is a sesquiterpenoid. Sesquiterpoenoids are interesting molecules: the most widely used antimalaria drug in use today, called coaterm, contains a sesquiterpene extracted from Artemisia annua.

This powerful ingredient was discovered by Chinese scientists working under on the order of Mao Zedong. They screened 2000 traditional Chinese medicines, testing 380 extracts. But the clue was found in a book written during the Han Dynasty (over 1800 years ago) which recommended wormwood for treating ‘intermittent fevers’, a symptom of malaria.

Artemisinin was trialed on mice, then self-administered by the researcher, Tu Youyou. Apparently all survived and the drug was used in China in the 1970s, taking longer to reach the rest of the world due to China’s isolation during the Cultural Revolution. So a good news story, luckily. Tu Youyou still lives and works in China today according to Casey.


Artemisia arborescens

There are sure to be other useful (to man and mouse) ingredients in the chemical cocktail within wormwoods. Meanwhile they provide a handy plant for drought-stressed gardens in Melbourne. So tough they sometimes stray beyond the walls. Artemisia arborescens, the Silver Wormwood, has become naturalised in New South Wales and South Australia but although persisting around old gardens in Victoria it isn’t yet (as far as I know) considered to be a worrisome weed. The Chinese Wormwood, Artemisia verlotiorum, however, is, particularly on roadsides around Melbourne.

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Tim Entwisle

About Tim Entwisle

Dr Tim Entwisle is a scientist and scientific communicator with a broad interest in plants, science and gardens, and Director & Chief Executive of Royal Botanic Gardens Victoria. Previously he was Director of Conservation, Living Collections & Estates at Royal Botanic Gardens Kew and prior to that, Director of Sydney’s Royal Botanic Gardens for eight years. Read Tim's full blog at Talking Plants

3 thoughts on “Wormwood for fever not flavour

  1. Hi Julie. I don’t know for sure, but I’m presuming ‘wormwood’ in this context (Wormwood Scrubs) refers to a local Artemisia species, whether native or weedy. The term is used in old herbals, generally referring to this genus but occasionally to others. I’m away at the moment but have a book on the native flora of Kew Gardens at home that might give some clues – I’ll post again if I find something extra!

  2. Well, my trusty ‘The Wild Flora of Kew Gardens’ by Tom Cope includes Artemisia campestris (Field Wormwood) back as far as 1768 and assumed to be native. Artemisia absinthium is also a native of England, I gather, and is now cultivated as part of the Kew collection. So let’s assume Wormwood Scrub is named after the prison which was named after the scrubby growth of Artemisia in the area.

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