The Light Eaters by Zoë Schlanger

I will fight until my dying breath that popular science audio books narrated by their authors (or a narrator that gets it) are underappreciated wonders. They communicate facts about our world with joy, wonder and enthusiasm.  I listened and read this one (mostly listened) and found it as weird and wondrous as Entangled Life (which Schlanger referenced). Granted, she wasn’t as enthusiastic as Merlin Sheldrake or Ed Yong with their books (I think that’s the journalist in her), but wow, plants are as weird. Lots of science is brought forward – plant communication (mostly chemical), electrical senses, touch/hearing, sight, memory, communication with animals(!), mimicry, recognize kin and many other things. I’d never thought that a plant was capable of such things. I also learned about plant blindness (guilty) and how that gets in the way of much observation. But it also had me pondering what the umwelt of a plant is like. Helluva book. 9 stars ★★★★★★★★★.

Schlanger started The Light Eaters as a project to counter the consistent doom and gloom of her job as a climate reporter at The Atlantic (I won’t hold that job against her) and how we’re still learning weird, wild and fascinating new things about plants. Including something that’s been taboo since The Secret Life of Plants came out in 1973: plant intelligence and behavior. This is still controversial enough in botany circles that most botanists and plant scientists avoid engaging with it. Or describe it so circumspectly, you think they’re not talking about it all. She doesn’t say science advances one funeral at a time, but she certainly implies it over the course of the book. 

This book gave me a lot to chew over as she recounted scientific studies and papers that are unbelievable  against the widely received knowledge that plants are passive – they just sit there.  The reality is, we just may not experience the universe at the same speeds. A few are able to do things at a speed we can notice and we can notice more with our current sensors and recording devices. We’re also able to put aside our antho- and zoocentrism to really see.

She divides the book up into chapters, each addressing a different part of botany.

1. Questions ofPlant Consciousness
2. How Science Changes Its Mind (and the past dead ends, problems and roadblocks, specifically The Secret Life of Plants)
3. The Communicating Plant – how plants communicate via chemicals
4. Alive to Feeling – plant electrophysiology
5. An Ear to the Ground – plant senses
6. The (Plant) Body Keeps the Score – memory
7. Conversations with Animals – communication with animals, largely via chemicals
8. The Scientist and the Chameleon Vine – plant mimicry
9. The Social Life of Plants – kin recognition
10. Inheritance – how plants assist their offspring
11. Plant futures – new perspectives on plant life

It’s all fascinating and upends much of what I knew about plants. I’d heard about plant communication but didn’t know much. I thought it was limited to ethylene and ripening, but it goes beyond that. Telling each other about animal attacks and coordinating responses to the attacks. That the communications between related plants are privileged over those of unrelated plants, but isolated specimens will communicate with other species about threats. It even implies plant personalities – tolerance for risk at least. 

After A Vast World I learned about electrophysiology and its role in animal senses. And from reading other books, that plants generated positive charges (used by spiders and insects to travel), but due to my plant blindness, I’d never made the connection that a plant might make use of it as well. Which leads to the plant sense of touch and the main focus of the chapter. It logically leads to the next chapter and plants and hearing – which is after all nothing more than remote touching?

The idea of memory in plants is mindblowing, yet Schlanger brings the evidence. It starts with Nasa poissoniana’s ability to remember the frequency of bumblebee visits for pollination and take advantage of that by positioning its stamen to best make contact with the pollinator. But how does something without a brain have a memory? Then there’s vernalization – convincing a plant that a winter has happened and thus it’s time to sprout. That’s epigenetic and passed down from one generation to the next. But still there’s evidence of learning and memory by plants independent of that. Dodder vines which count the loops of vine they wind around plants they parasitize. 

Then there are plant communications with animals. From producing nectar and fruit to entice animals to pollinate, to creating compounds that poison pests to others that draw predators of their pests. Those same chemoreceptors plants use to communicate with each other are used to interact with animals. Suddenly, Semiosis doesn’t seem so far-fetched. 

Then there’s mimicry. It’s widespread in the insect kingdom, but not unknown in plants. However, Boquila trifoliolata takes it to a new level – not just mimicking one species, but other plants it’s exposed to. How it does it is still a mystery, but it is uncanny and potentially evidence that (at least some) plants can see. Which makes a sort of sense given their dependence on light. Boquila deserves its own book because it is one weird plant and given how plants repeat things, I doubt it is the only one.

Then there’s kin recognition. I mean, we do it. Insects do it. But plants? Guess what, they do. The staghorn fern in Australia is eusocial, with some plants sacrificing their reproduction for the good of the colony – just like ants, bees and wasps.

Inheritance for plants goes beyond epigenetics and genes. No, some plants plant their seeds where they’ll grow well. Just like people will pass down land to their children.

Then there’s the future – and while it can be grim, there’s also hope that humans may shift their views on plants to honestly appreciate them as the unique entities they are.

So, are plants conscious? Maybe. Botany is still wrestling with this and likely will be for years. But Schlanger makes a good argument and makes me think they may be, but on a different time scale than us. Mind opening book that’s well done. 

9 stars ★★★★★★★★★.