"It's a classic. The inside of the seed makes castor oil but the outer is completely toxic. A spy was stabbed with an umbrella on London Bridge tipped with the tiniest bit of the outer husk, and dropped dead in minutes. It was ricin, of course."
In the Chelsea Physic Garden, on the north shore of the River Thames, head gardener Nick Bailey is trading botanical notes and grim stories with Ryan Chetiyawardana, award-winning bartender and the brains behind one of London's best loved bars, Dandelyan.
Medicine and poison—the line between the two is fine, and one that Dandelyan's latest series of drinks treads. With the greatest of care, of course.
I'm here with Chetiyawardana to understand how actual botany informs the drinks made at a bar whose running theme is "Modern Botany." In terms of plant-based anecdotes, I'm getting a lot more than I bargained for.
"It's fitting that we're here," says Chetiyawardana. "This garden was set up to explore plants for medicine, but they're all related—perfumery, medicine, apothecaries, booze. The gardens show how they all fit together in a unique way, and really we just try to understand them better so we can draw the deliciousness out of them."
It seems that when a bartender asks you to pick your poison, they're kind of being serious. Make an extraction one way and it could be a tonic; make it another and it could be toxic.
"Everybody thinks of plants in terms of vegetarianism, like they're clean and nice. But nature is full of vice, and so we've explored the slightly sinister side of plants. These are pretty gruesome," he says, gesturing to some benign looking succulents in one of the glasshouses. Turns out they're actually carnivorous. Some of these plants give off the smell of rotting flesh to attract flies so that they can get their proteins directly.
Thankfully there's no dead body smell lingering in the garden today, but it certainly does put an interesting spin on the idea of plants as "harmless." To illustrate the point, Bailey leads us to the poison section of the garden, which as it happens, is right next to the pharmaceutical flowerbeds.
"If you look at them, they're basically identical collections," he explains. "It's all about the dose. Take thyme for example. The act of compounding thyme produces thymol, which is a biocide. That means it could literally kill every organism on earth. It's only because we have it in such tiny doses that it doesn't kill us."
I gulp. Chetiyawardana just laughs.
His team tease their customers along these lines, naming their cocktails things like "Arsenic Waltz" or "Lonely Heart Killers." Of course, they're not lethal, unless—as with any alcoholic beverage—you consume an insane amount. It's Chetiyawardana's way of making the point that plants can have a dark side.
The Arsenic Waltz he explains, in spite of its name, is actually made from leftover cucumbers turned into a honey that captures a vibrant greenness. Its name is based on how frequently humans have danced with danger in the pursuit of their own vanity or lusts.
"Arsenic made its way into a lot of make up, and there was mercury in hats. So we created a tequila sour that plays with that idea."
Of course, plants have their virtues too—some more real than others.
"Hypericum has been taken for years as an antidepressant," comments Bailey. "You'll have come across it as St John's Wort. Everybody swore by it, but it's been proven categorically to be ineffective. However, the same study that named St John's Wort as a placebo, also proved that passiflora is highly effective as an antidepressant. It makes great rolling tobacco as well."
This is another line of inquiry Chetiyawardana explores at Dandelyan: the faith that people put into plants, for good or for ill.
"We made a drink called 'The Flower of Five,' based on passiflora," he explains. "Spanish missionaries called it 'the flower of Christ,' and retrofitted the crucifixion story to different parts of it to symbolise the crown of thorns, the five wounds of Christ, or the Trinity."
As a tip of the hat to this, Dandelyan's version even includes an extract of leather to symbolise the whips used in the story. And to add a roundness to the flavour of the drink, of course.
"Through different times, plants have become intoxicants or they've become hallowed," Chetiyawardana adds.
So Passiflora, or the passionfruit flower, is an example of a plant that took on holy connotations. Wormwood, on the other hand, was less fortunate. Pausing by a clump of it, Chetiyawardana picks a leaf and lets me smell it.
"I think it has an amazing vanilla creaminess to it, and it's very green as well," he says. "But it tastes ungodly bitter."
The warning comes just before I'm about to give it a nibble: "And once it's dried the flavour's even more concentrated."
Wormwood lent its name to "vermouth" from the German vermut, but before that, it was a herb used in Morocco to make teas, and here in Britain in beers before hops were used.
"Obviously, it crops up in absinthe and that's when it got demonised," says Chetiyawardana. "It was blamed for lots of terrible things when it was more likely the alcohol had been laced with turpentine."
And then, of course, there are the plants that actually do have medicinal value, appropriately enough, given this is a physic garden, one originally grown strictly speaking for medicinal purposes.
"A lot of modern cancer drugs reference very historic plants," says Chetiyawardana. "This is where old wives' tales and science interact, because a lot of things were done because they worked and this became the foundation of modern medicine."
He cites aspirin extracted from willow trees, which had long been known to alleviate pain when made into a tonic.
In honour of this crossing point between folklore and science, vices and virtues, botany and booze, Chetiyawardana has made a drink called "Mmm Hop." It has a tree sap cordial as a nod to the aspirin, periwinkle, which is used as a cancer treatment drug, and hops that are a relative of marijuana—that great controversial pain reliever of our times.
Medicine or poison? It's hard to say. Maybe the seduction of plants in alcoholic form is what makes them most perilous. As far as I'm concerned, if the liquid in my glass is delicious, I'll sip it down, hoping that I'm actually drinking the true elixir of life.
This article originally appeared on MUNCHIES on February 24, 2017.