Read all about it: Plants that get their own back on animals

Carnivorous Plants by Dan Torre 2019. Reaktion Books Ltd.

In the same way that it’s become something of a tradition that books about seeds should contain – and prominently – that Henry David Thoreau ‘seed quote’ * (e.g. Seeds, Sex and Civilization, 2010, by Peter Thompson; Thor Hanson’s The Triumph of Seeds, 2015), it’s seemingly almost compulsory that text-based items on carnivorous plants must include the quote attributed to Charles Darwin that they are the “most wonderful plants in the world” ** (e.g. Melissa Dowland, Martin Fone, Aaron Ellison and Nicholas Gotelli, Thomas Gibson and Donald Waller, Elżbieta Król et al., Joni Cook, Loughborough University PhD, 2014, and Alexander Davis et al.). There’s nothing really wrong about using those quotes – and the temptation to use them is understandable – but, just as I find the Thoreau quote a little wearying, the Darwinism also gets somewhat tiresome. So, the important question we must consider at the start of this book appraisal is: Did Dan Torre in his new book Carnivorous Plants fall into that trap [yes, carnivorous plants pun acknowledged]? No, he didn’t ***: Yay!

What he did do is start the book with the rather understated opening sentence: “Carnivorous plants represent one of the most extraordinary groupings within the plant kingdom”. Thereafter, Torre’s text testifies to the truth of that bold claim, and in so doing comprehensively attests to the wonderfulness of these plants.

Accordingly, packed within Carnivorous Plants are 192 pages of text (an Introduction and 6 Chapters), 8 pages of References and Further Reading (which includes over 110 items dated 2005 or later), 3 pages of Associations and Websites (to further one’s interest in matter phytocarnivorous), 6 pages of 2-columned Index (from action potential to zoophytes), and 132 illustrations (of which 102 are in colour). And all of this is wrapped up in Torre’s great writing style.

For what it may be worth, and by way of tempting others to explore Torre’s truly tantalising text, here’s my overview of the book’s main sections.

Introduction: Over 700 carnivorous plant species are known, but more are ‘found’ each year as the carnivory definition is expanded. The problem of determining whether a plant is carnivorous is exemplified by the case of Dipsacus fullonum (teasel). Although this plant does not feature in Torre’s book, this carnivory-categorisation conundrum is well illustrated by considering and comparing the papers of Peter Shaw and Kyle Shackleton, and James Krupa and J Matthew Thomas. And this semantic imprecision is not helped by inclusion of a ‘semi-carnivorous’ category. Maybe all of this confusion can be avoided by Torre’s reminder that all plants are effectively carnivorous – benefiting as they do from absorption of digestion products through their roots. And, since some of that material may derive from plant material, perhaps we should just categorise plants as ‘cannibals’ and have done with it [although that designation strictly only applies to absorption of digestion/decomposition produces of the same plant species as the nutrient-gainer…]..?

Chapter 1 Natural history of carnivorous plants: A most impressive natural history of all the – currently acknowledged and accepted (!) – carnivorous plants: including Venus fly-trap (the most famous and most theatrical member); sundews; rootless Aldrovanda, Utricularia, and the corkscrew plant (curiously, the only carnivore not illustrated in the book); Philcoxia (a subterranean carnivore – as is the corkscrew plant); and the pitcher plant genera Darlingtonia, Nepenthes, and Sarracenia.

Chapter 2 More than just a meal: With an important reminder that some carnivorous plants don’t do their own digesting via plant-produced and secreted enzymes, but rely upon the animal-eating actions of other organisms – then absorb those helper’s excrement. Which leads the author to propose that such plants shouldn’t be called carnivorous, but rather classified as coprophagous. Mention here too of the notion of ‘murderous plants’. But – and somewhat surprisingly – no mention of Mark Chase et al’s review of the same name that sought to broaden the definition of plant carnivory (and therefore a publication also worthy of being mentioned in the book’s Introduction…).

Chapter 3 A remarkable discovery: Repeating the incredible suggestion that the human propensity for evil derives from plants(!!).

Chapter 4 Attack of the killer plants: Noting that carnivorous plants have inspired several flights of phytological fear and fancy, several examples of that literary genre are considered. Interestingly, there in which chloroform is used to make the monstrous botanic – Sarracenia Nepenthis [sic.] – go limp and release the botany professor it was in the process of eating. Recognising that chloroform is a well-known anaesthetic for humans, I wonder if this 20^th century ‘reference’ was in any way an influence upon Ken Yokawa et al. in their 21^st century studies of Venus fly-trap and sundew anaesthesia? But, maybe the greatest surprise in this chapter was the revelation that there is a sequel to follow-up John Wyndham’s The Day of the Triffids. Written by Simon Clark, it’s entitled The Night of the Triffids…

Chapter 5 Magnificent carnivores: A consideration of the inspiration that carnivorous plants have been for engineers, their role in traditional cultures, food, and medicines, and how they’ve been celebrated in art and design. This chapter also showcased the curious artwork of Madeline von Foerster, and amazing glass and steel constructions of other living artists, and reveals that the carnivorous plant Cephalotus is shown on the United Nations’ 32 cent stamp of 1996 [who knew that the UN issued stamps?]. It also includes the revelation that some carnivorous plants are used in homeopathic therapies.

Chapter 6 Collecting, growing and conserving carnivorous plants: Appropriately, after the sometimes frivolous and more amusing insights in carnivorous plant biology and iconography in preceding chapters, Torre ends on a rather more serious note. The final message in this book is one of conservation conservatism and caution: Just as it is for lions and tigers, habitat destruction is a big threat to carnivorous plants in the wild ****. If these wonderful plants are to continue to amaze and inspire us, we need to look after them.

Summary

Reaktion Books’ Botanical series continues to impress. Overall, Carnivorous Plants is a highly readable, informative, and entertaining natural history of carnivorous plants (and one’s appetite is sufficiently whetted to want one now to devour Torres’ Cacti…).

* “Though I do not believe that a plant will spring up where no seed has been, I have great faith in a seed. Convince me that you have a seed there, and I am prepared to expect wonders”.

** This oft-quoted phrase is, however, seemingly an optimistically all-carnivorous-plants’-embracing corruption of “THIS plant, commonly called Venus’ fly-trap, from the rapidity and force of its movements, is one of the most wonderful in the world” (p. 286 of Darwin, C. R. (1875) Insectivorous Plants. London: John Murray). However, this clearly and specifically only applies to Dionaea muscipula. Although Darwin also wrote elsewhere “at the present moment, I care more about Drosera than the origin of all the species in the world’ (Darwin 1860, in a letter to Charles Lyell, cited in Aaron Ellison and Nicholas Gotelli (Journal of Experimental Botany 60: 19–42, 2009; doi:10.1093/jxb/ern179)). Which two quotes together can be held to support a view that Darwin considered carnivorous plants in general to be wonderful. Which they are.

*** Mr Darwin’s ‘wonderful plant quote’ is only mentioned in Carnivorous Plants in passing, when quoting from ‘low-budget horror movie’ Body of the Prey which features a mutant carnivorous plant monster.

**** Something brought home to us in the UK with an initiative to try and protect the English sundew, Drosera anglica, reported by the BBC.