Plant Sensing & Communication. Richard Karban. University of Chicago Press, 2015

It is said that we have two ears and one mouth because we should listen twice as much as we talk. Well, if we listen to the plants what do they say? And is it something to talk about? Short answer is that plants ‘say’ a lot. But, it’s not just something to talk about, it’s something that should be shouted out loud! And that’s what Richard Karban does in Plant Sensing & Communication [hereafter referred to as Sensible Plants]. His thesis is simplicity itself; plants do communicate [‘talk’] and other plants (and not just of the same species…) – and microbes, and even some animals – do listen.

But it’s not just the communication side of things, it’s important to have something to communicate, and that’s where the sensing aspect comes to the fore – plants are intimately interconnected with, and intriguingly sensitive to and in-tune with, their environment, both its inanimate and animate components. And they’ve had to be. Generally, they are fixed to one spot throughout the greater part of their lifecycle and either cope with the environment and persist, or perish. They can’t run away like animals if the surroundings aren’t to their liking; they either put up or get put down. And over millions of years they have become exquisitely attuned to their external milieu and able to detect and interpret subtle – and sometimes not so subtle – abiotic and biotic cues and signals, correct interpretation of which and appropriate responses thereto is often a matter of life or death to these sedentary soil-dwellers.

So, Sensible Plants (yes, I know it’s a little provocative, and why not?) deals with the many factors that plants are sensitive to – e.g. light, chemicals, touch, temperature, electricity, gravity, sound – and their responses as a result of detection thereof. Karban’s book also considers whether plants learn and have memory (both topics that have come back to human attention in recent years). There is quite a lot about plants detecting ‘cues’ and signals in connection with herbivory and the responses those elicit. And, having escaped the trophic attentions of herbivores, the world of pollination and reproduction more generally is explored. Demonstrating the co-operative nature of plants there is a whole – but comparatively short – chapter devoted to instances of plants communicating with fungi, N-fixing bacteria and more harmful microbes. And this also extends one’s appreciation of the ever-expanding range of compounds in the plant hormones category such as jasmonates and strigolactones (though, and curiously, there appears to be no mention of the molecular dialogue that ensues between certain flowering plants and their would-be nutritional extortionist, the parasitic angiosperm Striga, and after which genus the last mentioned ‘information molecules’ were named…). And, if any human doubted the existence of plants’ multiple sensory and communication capabilities, surely the final chapter entitled “Plant sensing and communication in agriculture and medicine” is an end to the debate. For that section undoubtedly puts all of the preceding 162 pages into their proper perspective in considering how this new-found (or recently resurrected..?) botanical knowledge can be exploited, for the benefit of humankind. Now that there is a definite anthropoexploitative WIIFM dimension to it all, plant sensing and communication must surely be considered a legitimate topic of study (and a genuine phenomenon…)?

Sensible Plants is a comparatively slim volume with 179 pages of text (and >9 pages of 2-columned index), but it packs in a tremendous amount of material: Each of the book’s 10 chapters could easily form the basis of at least one lecture – and would be great material for ecology, plant biology, agriculture, or general biology courses (and also worth inserting into an animal biology course to show how alike plants are to animals in many ways(!)).

Having read Sensible Plants shortly after completing Trewavas’ and Kennedy’s tomes I felt I was well versed in many aspects of the communication/environment-sensing aspects of plant behaviour, but Karban places those phytological phenomena upon a much broader canvas. So, if you can set aside any prejudices about animals being superior to plants (and I know that’s harder for some to do than others), just allow yourself to wallow in the extraordinary botanical sensitivities documented in the book. And wallow is the right word because Karban ‘hits’ you with insight after insight into the sensory world of our chlorophyllous cohabiting companions. But, make no mistake, Sensible Plants is not just an adjunct to, or the ‘lite’ version of, that doyen of the plant intelligentsia movement Tony Trewavas’ 2014 tome on plant intelligence and behaviour. Karban’s contribution stands on its own as a separate, rigorous academic text that adds considerably to Trewavas’ text. And – dare I say it? – probably in a more accessible way; Karban’s book reads more like a novel than a textbook or high-brow, philosophical, academic read that is a feature of Trewavas’ tome. That is not to say that Sensible Plants isn’t rigorous; it is, with >52 pages of references (approx. 120 of which are dated post-2011), and the text is thoroughly referenced throughout (and in author’s surname order unlike Kennedy…). Indeed, it is because Sensible Plants is so rigorously evidence-based and represents serious, sober science that its message is even more persuasive (and let’s not forget that science communication is about persuading others of the veracity of one’s claims).

But, what of Karban’s credentials for writing this book? Interestingly, Richard Karban is professor of entomology at the University of California, Davis (USA), which might seem to make him an unlikely proponent of plant sensitivity. However, it is his zoological background and researches – in particular enquiry into plant defences against insect herbivory – that uniquely qualifies him to write about this most phytocentric of phenomena. And if botanists need to be told how amazing plants are by an entomologist, well so be it. [Or, if zoologists can appreciate how awesome plants are, who are we to contradict them?]

Sensible Plants joins the swelling ranks of texts – some maybe more populist than others – that are setting the record straight on what plants can do and how remarkable they are. Sensible Plants therefore takes its place alongside the following (listed in publication date order): Chamovitz (2012), Manetas (2012), Trewavas (2014), Mancuso and Viola (2015). Plants are amazing and do things that we find quite incredible. And why not? After all, they’ve been playing the survival game far longer than us. What a fertile furrow in the field of phytology is – and not before time! – being ploughed. More, please!

Overview

Plant Sensing & Communication is a wonderful book; not least because it is a celebration. A celebration of the exquisite sensory capabilities of plants, and an exploration of their capacity to communicate with other entities. How refreshing it is to live on a planet where our green neighbours have such extraordinary talents. And how thrilling is it that humans – if they try hard enough and aren’t blinded by notions of zoosupremacy – have the capacity to appreciate, explore and understand that side of those resourceful organism with whom we share the planet. Even if some humans still remain resolutely plant-blind (Allen, 2003), it is clear that plants themselves are anything but blind; they see their environment extremely clearly and with great acuity. Now, if only we could all see plants in the same way…

References

Allen W (2003) Plant Blindness. BioScience 53: 926.

Chamovitz D (2012). What a plant knows: A field guide to the senses. New York, NY: Scientific American / Farrar, Staus & Giroux.

Kennedy DO (2014) Plants and the Human Brain. Oxford University Press.

Mancuso S and Viola A (2015) Brilliant Green: The surprising history of plant intelligence. Island Press.

Manetas Y (2012) Alice in the Land of Plants: Biology of Plants and Their Importance for Planet Earth. Springer

Trewavas A (2014). Plant Behaviour & Intelligence. Oxford University Press.