Three more consciousness-altering substances, each derived from a plant, are the focus of Pollan’s latest book, This Is Your Mind on Plants: opium, caffeine, and mescaline. Largely consisting of previously published material – the chapter on opium appeared in the April 1997 issue of Harper’s Magazine, while the section on caffeine originated as an audiobook in 2020 – This is Your Mind on Plants feels like an extended coda to the previous book. As in How to Change Your Mind, Pollan sketches each plant’s history and pharmacology, and, through the time-honoured device of ‘trip’ reports, describes what happens when he takes them (or, in the case of caffeine, so ubiquitous as to be barely thought of as a drug at all, when he doesn’t).

In the chapter on the opium poppy (Papaver somniferum), source of the ancient ‘milk of paradise’ that has brought sleep, pleasure, and pain relief – not to mention war and today’s opioid crisis – to millions, Pollan recounts his attempt to grow opium in his garden ‘just to see what would happen’. The result was not merely a magazine column on a novel subject but ‘a living nightmare’ of anxiety and paranoia that Pollan describes in language that now seems overwrought, though we are urged in a contextualising prologue to read it through the lens of the heightened anti-drug atmosphere of the late 1990s.

While the seeds necessary to Pollan’s experiment were readily available, establishing the plant’s legal status proved a thornier matter, turning on questions of not only intent but also knowledge. The situation becomes so vexed that Harper’s lawyers urged Pollan to excise from the article his recipe for tea, and the positive description of its effects, so as not to incriminate himself or the magazine. These pages – reinstated here for the first time, having been handed to Pollan’s attorney for safekeeping on a floppy disk – make for fascinating reading; Pollan writes of a ‘lightening of his existential load’, of feelings of anxiety, melancholy, worry, and grief disappearing.

Caffeine, Pollan notes in the following chapter, is by far the most used psychoactive compound of all, consumed by some ninety per cent of the global population, and delivered primarily by the plants Coffea (coffee) and Camellia sinensis (tea). It also may have done more than any other drug to shape the course of the West through its entrenchment as a productivity booster during the Enlightenment and then, in the form of the coffee break, under capitalism. Like opium, it too has been a source of conflict and oppression, its production still reliant on exploitative labour practices to this day. In another sign of our multifaceted relationship with these plants, Pollan reminds us that, while we have spread Coffea to every corner of the globe, it is now one of the crops most threatened by the climate crisis.

In order to assay the effects on him, Pollan forswears caffeine for three months. ‘I came to see,’ he writes, ‘how integral caffeine is to the daily work of knitting ourselves back together after the fraying of consciousness during sleep. That reconsolidation of self – the daily sharpening of the mental pencil – took much longer than usual and never quite felt complete.’ As Pollan details his arduous return to functionality without caffeine, he also ponders one of the most interesting questions arising from his research: why should these bitter-tasting compounds, each of which began as a chemical to defend the plant from animals, alter consciousness at less than lethal doses? One intriguing theory holds that it’s in the interest of the plant to disable rather than kill its predators, ‘since the toxin,’ as Pollan notes, ‘selects for resistance, rendering it harmless’.

One of the chief criticisms of How to Change Your Mind was that Pollan failed to engage with indigenous voices, especially given the longstanding importance of the ceremonial use of mind-altering substances in such cultures. The final chapter of This Is Your Mind on Plants, which focuses on the potent, cactus-derived psychedelic mescaline, feels, in part, like a corrective to this. Pollan notes the at least six-thousand-year-old use of the peyote cactus by the indigenous peoples of North America, as well as its appeal to Westerners like the French dramatist Antonin Artaud, who was drawn to mescaline precisely because it ‘was not made for whites’. We now broadly understand this as cultural appropriation, and in the end, following extensive consultation with Native Americans, Pollan decides not to take part in a traditional mescaline ceremony, procuring instead two capsules of a synthetic version of the drug.

The ensuing trip report recalls Aldous Huxley’s famous description of mescaline’s effects in The Doors of Perception (1954). ‘It was incredible how much there was to see!’ Pollan writes. ‘The pelicans lumbering over the water before slowly climbing into the sky. The diamond reflections of sunlight glancing off the ripples in the bay. The crazy shade of chartreuse in Judith’s socks. I was captivated by it all, and could not imagine ever wanting to do anything but devour with my eyes all that there was to see.’

In recent interviews, Pollan has spoken of his interest in starting a ‘post-drug war’ conversation. Now that the dark days of prohibition seem to be waning, how, Pollan asks, can we begin to create a cultural context for the safe and meaningful use of psychedelic drugs? While bolder answers to this question have been attempted elsewhere – I’m thinking especially of recent books by Julie Holland and Carl L. Hart – This Is Your Mind on Plants nevertheless succeeds in gathering further, masterfully presented evidence of the war on drugs’ failure, and the pressing need to rethink our relationships with the plants that change our minds.