The geek’s guide to weird and wonderful plants

Hortus Curious: Discover the world’s most weird and wonderful plants and fungi, Michael Perry, 2022. Dorling Kindersley.

I recall feedback about my undergraduate marine biology module along the lines of “Nigel uses the phrase ‘weird and wonderful’ far too much”. Well, if that former student is reading this blog item I encourage them to look away now because that phrase is going to be used again. Not by me, and in connection with plants rather than denizens of the marine world on this occasion. Why? Because discovering the world of weird and wonderful plants and fungi is what Michael Perry invites us to do in Hortus Curious [which book is here appraised].

Mainly overview/technical…

Hortus Curious is a comparatively slim book of approx. 173 pages of main text, and begins with a Table of contents that lists the titles of the individual articles [which are phrased as ‘sound-bites’ (Anastasia Kovalenko) that intrigue and encourage one to read them] under the book’s named sections, along with the scientific name (or, rather, the Latin name as the author prefers to call the scientific binomial) of the plant that is show-cased in that item.

After a short Introduction, in which we are invited to “Step inside Mr Plant Geek’s world of plants” (pp. 6-9), we do just that. There therefore follow five sections: Plants behaving badly [in which “you’ll find out about insect-trapping plants … plants that are flammable … and others that smack unsuspecting bees with pollen” (p. 9)]; Mistaken identity [where “you’ll encounter the plants that are often the subject of memes (Alexis Bienveniste; Jon Martindale) … plants that resemble flying ducks, or penguins running over a mountain, or even a dead man’s hand reaching out from the forest floor” (p. 8)]; Greater good [in which “we look at the most commercially successful plants the world has ever seen” (p. 8) – such as tea, coffee, peanut, and rubber]; Superheroes [wherein Perry celebrates plants that are “the longest, smallest, luckiest, and even the one that’s the greatest dancer” (p. 8) – e.g. resurrection plant, coco de mer, and Wollemi pine]; and X-rated [for which selection – such as Clitoria, and Phallus – you’ll “need to put your inhibitions to one side … and prepare yourself for general indecency, squirting cucumbers, and devil’s fingers” (p. 8)].

Each plant entry is four pages long, abundantly-illustrated by Aaron Apsley [who has managed to capture the structural-blue coloration of Pollia fruits (Ed Yong) well – which is no mean feat], and has a formulaic start that provides the following information: the plant’s common name; How big is it?; Where is it from?; What’s its natural habitat?; How does it reproduce?; and Can I grow it at home? [a feature that is probably unique to this publication, and which may encourage those who’ve never grown plants before to do so – inspired by the tales in the book]. The plant’s Latin name is given at the foot of the first page of each item. And, amongst the text, a ‘How curious’ weird or wonderful fact is highlighted for each plant entry.

The book showcases 40 ‘botanics’. Although primarily devoted to angiosperms, it also features a couple of gymnosperms (Pinus longaeva (Christopher Earle) and Wollemia nobilis), three fungi* – Clathrus archeri, Phallus impudicus (Shaun Chavis), and Xylaria polymorpha, and Selaginella lepidophylla (Fernando Matos).

Hortus Curious concludes with an Index and a Bibliography. The Index consists of six, 2-columned pages of Index, from acacia, bullhorn to Zimmerman, Tony, via burning bush; Christopher Columbus; dead man’s fingers; exploding cucumber; Fair Trade; geckos; hot lips; International Cocoa Quarantine Centre; Jagger, Mick; labellum; miraculin; neurotoxins; Olmec Indians; pennate foliage; root rot; snakebite remedies; tear gas; vibration; and water eggs.

The Bibliography covers four pages with a general section [a few plant-relevant books and lots of plant-appropriate web sites], and items under each of the book’s five named sections. Section items are a mix of web sites – including two entries for the Botany One blog (always nice to see) – and scientific articles. However, no URLs are given for those web sources, and volume and page numbers are missing from the scientific articles that are listed. So, although it is possible to track down the specific sources stated, it would probably be unnecessarily time-consuming to so with such limited information. Which is a shame for the reader whose botanical interest and enthusiasm has been sufficiently sparked by Perry’s words to want to find out more to satisfy their new-found interest in plants, and improve their botanical literacy.

Appraiser’s appreciation…

Hortus Curious has an easy-reading writing style that’s enlivened by personal anecdotes, is not overly-technical, and is enjoyable. If telling tales about quirky plants helps to educate (inform and entertain…) new readers and improve their botanical literacy, it’s a job well done. It’s also a lovely book, full of interesting botanical titbits, and Perry is a very enthusiastic and knowledgeable guide to the botanical realm. Indeed, the author is “a leading gardening personality” (p. 191), and may be better known to some readers as Mr Plant Geek who, in 2015, was listed in the Top ’20 most influential horticulturists’.

Perry has a gift for nice phrasing, and ‘sound bites’ that maintain your interest in the book’s subject matter and encourage you to keep reading, e.g. this great opening sentence to the entry for pineapple: “Pineapples have been involved in all sorts of dramas over the years, from being the subject of aristocratic rivalries to getting caught up in the drugs trade” (p. 96).

Although there is plenty of humour throughout the book, quite a lot of it is ‘British humour’ (Evan Evans; Alan Peters) that may not work so well beyond the UK (and there might be just a tad too much of it..). Whilst it might have been useful to give some photographs of the plants, these can be readily found on the web; the bespoke watercolours by artist Apsley, prepared specifically for Hortus Curious, cannot.

With tens of thousands of plants to choose from, how did Perry whittle it down to just 40, and why this particular collection? The selection of plants is the personal choice of the author, who says that “In some ways, you could say that this book is a bucket-list of plants that I want to spend time with” (p. 9). And who can argue with that?

The book’s intended audience is hinted at by the author’s hope that “you have enjoyed the book, whether you’re a plant obsessive, complete novice, or anything in between” (p. 190). Furthermore, “This book is dedicated to anyone who has ever been intrigued by plants, but is put off by all those big, heavy, and serious books with wall-to-wall Latin names and unfathomable botanical terms” (p. 190). Nevertheless, technical terms are used where appropriate and necessary, and generally they are explained when introduced – e.g. pinnate, detritivore, and geocarpic. But, neither mutualistic association nor genus are defined, and I have no idea what the phrase ‘some serious catfishing’ (p. 54) means. Pseudocopulation isn’t defined either but, as Perry advises us, this is a term “which needs no explanation”…

In reading Hortus Curious I am reminded a little of The Strangest Plants in the World by the Talalaj trio, Prof. S., D. & J., which has many species in common with Perry’s selection, and also concentrates on the weird and wonderful of the botanical world. The inclusion of Clitoria and Phallus in the same section of Perry’s book also brings to mind the even more outrageous closeness and orientation of the drawings of that flowering plant and fungus at the beginning of The Sex Life of Plants by Alec Bristow. And, for good measure, one sees some echoes of Francis Hallé’s Atlas of Poetic Botany (Mike Leggett) in Perry’s book. All three of which titles are fine company for Hortus Curious to now join.

Fascinating and fun, Hortus Curious by Michael Perry is an undemanding read that richly rewards the reader. It’s a great little book that’s educational, entertaining and informative; and would make an ideal present for the plant geek in your life.

Full of facts…

Hortus Curious contains lots of facts (subject to their being confirmed as such by the unnecessarily time-consuming fact-checking from the items listed in the Bibliography, because none of those stated sources are tied-in specifically to statements in-text). Those facts are carefully chosen to impress upon the plant-averse, would-be reader the weirdness and wonderfulness of plants and engender respect for these marvels of nature.

And there’s also plenty of new and/or forgotten information for ardent plant enthusiasts, who may have cause to use some of this material within their own writing projects or speaking engagements. Such facts include the existence of a non-carnivorous pitcher plant, Nepenthes ampullaria; the etymology of Beltian bodies; the presence of alkaloids in nectar from extrafloral nectaries of bullhorn acacia that cause addiction in ants; the use of sand-filled hura seed pods for ink-blotting; that arabica coffee (Coffea arabica) is a natural hybrid of C. canephora and C. eugenioides; and the existence of ‘yeungyeung’, a drink of tea and coffee mixed together. Whilst one could just take them at face value, one would like to see sources stated – clearly – for all of these facts.

I must also make special mention of ‘gympietides’** [more at Nature (585: 485, 2020; doi: https://doi.org/10.1038/d41586-020-02668-9, which comments on the article by Edward Gilding et al. (Sci. Adv. 2020; 6: eabb8828; doi: 10.1126/sciadv.abb8828) – both of which sources are included in the book but without the urls, volume numbers, etc.], here, and from Jennifer Sibbald]. Finally, the existence of the ‘egg and chips plant’ – which was created by Perry by grafting an aubergine plant [known in some parts of the world as an egg plant (Aneela Mirchandani)] onto a potato – was quite a revelation to me (and it was interestingly included in the Superheroes part of the book – readers must make their own minds up as to whether the plant or the human is the superhero here).

Need for some confirmation and correction…

In addition to the fact-confirmation mentioned in the previous section, two other statements would benefit from explicit statement of sources. First, is Aldrovanda – whose trap shuts in 10-20 msec according to Perry, but does that make it “the fastest mover in the plant kingdom” (p. 14)? Second, is gympie-gympie – also known as the stinging tree – “probably the most venomous ‘being’ in Australia” (p. 16), as Perry claims? Such claims require specific and explicit substantiation.

Elsewhere, Perry tells us that world peanut production is “an enormous 49 tonnes per year” (p. 103). That doesn’t sound that enormous to me, which led me to wonder if he’s stated the units correctly. My own researches suggest that is the case since global peanut production in 2018 was approximately 47 million metric tonnes. Also related to units, 18 cm is not equivalent to three-quarters of an inch (p. 52) [the distance between the seedsnipe’s beak and the top of its head…]; maybe 18 mm is intended? There is also an issue with the botanical categorisation of Selaginella on p. 125.*** Finally, on p. 5 the specific epithet of titan arum’s scientific name is shown incorrectly as titanium, it should be titanum. However, it is correct on p.154 for that plant’s actual entry.

Can you be too weird and/or wonderful?

With his focus upon weird and wonderful, Perry is mining a rich vein of botanical curiosities – which is widely-supported on the internet with freely-available resources (e.g. here, here, here, here, Melissa Breyer, and Aryeh Brusowankin). Whilst there is more – much more! – to botany and plants than the weirds and the wonderfuls, if highlighting these botanical ‘extremes’ is the road down which one has to travel to try and engender more engagement with plants amongst the general public, then bring it on.

Summary

You’ve got to like a book whose first sentence is: “Plants continually excite and surprise me” (p. 7), which is how Hortus Curious by Michael Perry begins. Thereafter we are entertained and informed with tales of 40 plants that do just that. Not only for the author, but also for his readers (including this reviewer). Full of surprises and fascinating insights into the world of plants (and a few fungi), this charming book is an undemanding read and should be on every plant-curious person’s reading list.

* For those who might question why fungi are here partnered with plants, Perry is shamelessly exploiting the ‘Shenzhen Code’ to very good effect. The Shenzhen Code is the current authority for naming of plants, and pronouncing upon matters of a botanical-nomenclatural nature. But, because of a historical quirk going back hundreds of years – when botanists studied all the then-known forms of life that weren’t animals (Brian Lovett) – it also rules on how to name algae and fungi (Nicholas Turland). In this way, there is precedent for – and legitimacy thereby given to – mention of fungi alongside ‘proper’ plants.

** The special mention referred to above relates to this statement by Perry: “The gympie-gympie’s toxin is so unique in the plant world that scientists have named it after the plant – gympietides” (p. 19). Gympietides are toxic compounds found within the stinging hairs of the plant scientifically known as Dendrocnide moroides (Marina Hurley). When humans come into contact with these compounds – e.g. by brushing against the hairs so that their contents are injected into the body – their neurotoxic nature can cause such pain that it’s been described as “like being burnt with hot acid and electrocuted at the same time” (Tibi Puiu). Although that extreme reaction makes the compounds ‘special’, special in this context relates to the following teaching opportunity that Perry’s statement provides.

Although Perry’s words indicates some surprise at these chemicals being named after the plant in which they were first discovered, there is a long tradition of doing so. For example catherine (from Catharanthus roseus), gossypol (from cotton plants, genus Gossypium), atropine (from belladonna, Atropa belladonna) and cocaine (from Erythroxylum coca, the coca plant) (Anna Marie Helmenstine), and Taxol from Taxus brevifolia (Daniel Dias et al., Metabolites 2(2): 303–336, 2012; doi: 10.3390/metabo2020303). In all of those examples – as you may already have deduced – the compound is named from the scientific name of the plant. Gympietides differ because their name comes from ‘gympie-gympie’, one of the common names of the plant, which in its turn is derived from ‘gimpy-gimpy’, the indigenous Australians’ name for the plant in the Kabi language. It’s always nice and respectful when one gives due acknowledgment of those peoples whose botanical knowledge long predates that of those who usually get to name these compounds.

For those who may now be itching to know more about plant stinging hairs generally, see Hans-Jürgen Ensikat et al. (Toxins 2021, 13(2), 141; https://doi.org/10.3390/toxins13020141). And if you’re interested in knowing a little more about the UK’s much-less-dangerous stinging plant, I recommend Richard Fisher’s article on Urtica dioica.

*** Selaginella is a vascular plant that is described variously as a ‘fern-ally’, spike moss (Larry Hodgson), club moss, and a lycophyte (Barbara Ambrose, Annual Plant Reviews 45: 91-114, 2012; https://doi.org/10.1002/9781118305881.ch3). Despite having moss in some of its common names, Selaginella is not a moss (Lucinda Lachelin). It is, however, considered by some in the horticultural trade to be a fern (and is so described by Perry on page 125). But, Selaginella is not a fern (Botany Karen). In view of the author’s many years of expertise in the horticultural sector, we can probably understand his use of the word fern to describe Selaginella so shouldn’t judge him too harshly in this regard. [But, what this does highlight is the need for a separate blog post devoted to ‘decoding’ or translating ‘horticultural botany’ into more conventional, scientific botany, but that’s something for another time…].