Sowing the seeds of future food security

The Age of Seeds: How plants hacked time and why our future depends on it, Fiona McMillan–Webster, 2022. Thames & Hudson Australia.

There is a scarily stark statement in The Age of Seeds by Fiona McMillan Webster [which book is here appraised]: “We’re only one or two really bad harvest years away from a large-scale food security issue” (p. 152). The connection between one harvest and the next is seeds. And what ensures the continuity of harvest – in addition to such considerations as better management of soil, crop protection, plant-breeding, etc. – is the fact that seeds can survive the time between harvesting and subsequent sowing, and germinate on cue to produce the next crop. Trying to understand how plants manage to do this – i.e. how seeds ‘work’ – is the primary focus of McMillan-Webster’s book. Consequently, The Age of Seeds delivers a bumper crop of the biology and ecology of seeds, and its relevance to humankind – its past, present, and uncertain future.

Mainly technical

The main text of The Age of Seeds is essentially 280-plus pages of continuous prose separated primarily by the chapter headings. And headings such as ‘How humans changed seeds’, and ‘An arctic [shouldn’t that be Arctic?] fortress’ give some idea of the chapter’s content. Whereas, others such as ‘A mystery of mysteries’, ‘On sacred ground’, and ‘Come and see, I have a room here’, don’t give that much of an indication of the topic covered. However, having committed to reading the book even those obscure-sounding chapter titles do make sense – in hindsight. Within each chapter, there are no sub-headings or such-like to provide signposts to the reader indicating the content of the paragraphs that follow. But, since each of the 16 chapters is relatively short, and the writing is so good [see Mainly appreciative…], their absence isn’t too much of a hardship. Given the photogenic nature of some of the seeds, and the plants, one might have expected lots of pictures – if only as a way of providing some variety within the text. But, although there are black-and-white images at the start of each of the book’s six Parts, The Age of Seeds is otherwise devoid of images. That’s a shame.

There is no separate listing of references that provides sources to support the numerous statements made in the book [more on this later, see Comments about sources]. Neither are there any suggestions of further reading, which is a pity since seeds are such important biological features I expect the readers would like to know more about them. In the interests of a public service, I hope I may be permitted this opportunity to suggest some: two titles from Carolyn Fry – The last great plant hunt and Seeds, Thor Hanson’s Seeds, The book of seeds by Paul Smith, An orchard invisible by Jonathan Silvertown, and Peter Thompson’s Seeds, sex and civilization.

There is at least one entry for every letter of the alphabet in the approx. 12 pages of two-columned Index [although I was surprised not to see one for the ancient date palm named Methuselah – the story of whose age-defying seed is told at length early on in the book]. There is another issue with a term that’s indexed, but not where one might expect it to be. In connection with the ecology of seeds and fire, karrikins (Gavin Flematti et al., BMC Biol 13, 108 (2015); https://doi.org/10.1186/s12915-015-0219-0) is mentioned 5 times in text, but is not separately listed in the Index, under ‘K’ where one feels – not unreasonably – it ought to be. Instead, it can be found immediately below the entry for butanolides – i.e. under ‘B’ – on p. 296. Although butanolide(s) is included five times in-text, it’s only mentioned once specifically in relation to karrikin (on p. 80). If you’d missed that in your reading, or if you hadn’t read the book but were interested to know if The Age of Seeds had anything to say about karrikins, you’d probably turn to the index to check. Unfortunately, to use the indexing format employed here for karrikin requires a considerable degree of knowledge about the compound’s chemical nature – which this reader for one doesn’t have. Without that insight you’d probably not find karrikin in the Index, give up on the book and look elsewhere. Which would be a shame. Wouldn’t it have been more helpful to have a separate entry for karrikin, or ‘karrikin(s) [see also butanolide]’? Maybe something to consider for future editions of the book?

Mainly appreciative…

The Age of Seeds is extremely well-written, and was a pleasure to read. Author McMillan-Webster is to be applauded for her engaging style, which employs lots of nice phrasing, and includes several quotable passages [one of my favourites is: “This deft evolutionary manoeuvre, this seed habit, changed our world, but it came neither quickly nor easily. It was, like all of evolution’s astonishments, the product of millions of years of molecular negotiations, as plants and indeed individual species found the contours of what physics would allow and chemistry would condone, all within the ever-shifting boundaries of the environment” (p. 291)].

Beginning with a focus upon seed longevity [with appropriate stories about germination successes of the 2,000-year old dates of Masada, ancient lotus seeds, and the myth of ‘mummy wheat’], and the ‘curious nature’ of seeds, the book’s first two chapters admirably set the scene for what follows. And the remainder of the text develops the notions encapsulated within the book’s sub-title – How plants hacked time, and why our future depends on it – and convincingly shows why an understanding of the biology of seeds is so crucial to human survival.

To do proper justice to the biology of seeds, the book covers a lot of seed science – and general plant biology and ecology. In the hands of a less skilful writer that could have resulted in something akin to a textbook. However, the science is so well-explained, and the more-technical material so seamlessly woven into the overall narrative, that all readers should be able to follow it. From that perspective The Age of Seeds is a very good example of science writing.

But, it’s not just about the seeds, the book has numerous mentions of ‘seed people’, especially present-day scientists working on seed biology. Their numerous contributions to the story of seeds are included via interviews, personal testimonies, anecdotes,* and explanations of the seed science they are doing [so fundamental are the people to this plant-based tale that they all appear to have their own index entries]. In that way, McMillan-Webster has provided a very human feel to the story, which makes The Age of Seeds another ideal addition to the blossoming genre of plants-and-people literature.

A great range of topics is covered in The Age of Seeds: From the Jewish stronghold at Masada in Roman-occupied Judaea, to the Nazi-besieged Soviet seed store held at the All-Union Institute of Plant Industry in Leningrad; from evolution of the land flora [the book contains a very good account of this pivotal phytological phenomenon], and development of the seed habit [which is also well-explained] to transcription factors, and hot springs in Rwanda; from the soil seed bank to the Cherokee Nation Seed Bank [not too surprisingly, the crucial, future-proofing roles played by seed banks globally feature prominently throughout the book]; from the rude-looking seeds of coco-de-mer to the glass-like nature of quiescent seeds (UM Narayana Murthy et al., Journal of Experimental Botany 54: 1057-1067, 2003; doi: 10.1093/jxb/erg092); and from Darwin’s finches [which we learn aren’t actually finches(!)] to jaguars and hummingbirds [and not forgetting cassowaries and orang-utans…]. What a journey, what a ride! And Fiona McMillan-Webster is a great guide. It’s easy to see how The Age of Seeds could be an award-winning book.

Comments about sources

Hints of sources consulted are given in-text, e.g.: “In October 2016, biologist David Domozych and his colleagues succinctly explained in the journal Frontiers in Plant Science that there…” (p. 44); “In a 2020 paper published in the Progress in Botany book series, botanist Ulrich Lüttge suggests…” (p. 49); “in a recent [although timely, this is a phrase that’s likely to be a ‘hostage to fortune’ for readers of the book in 10 or 20 years’ time who’ll have a hard time guessing the year of publication of the article] paper in the journal PNAS by University of Zurich researchers Rodrigo Cámara-Leret and Jordi Bascompte…” (p. 275). Many examples of this ‘device’ can be found throughout book, e.g. pp. 52, 55, 58, 64, 71, … 81, … 89, … 136… Unfortunately, in no instance does McMillan-Webster provide volume numbers, pages, full author listing, or titles of the articles. Readers therefore have a bit of a challenge on their hands tracking down these items for further investigation, etc. Although incorporated into the text reasonably deftly, it still feels a little ‘clunky’ as a way of providing the much-needed, all-important sources for statements made. [And – somewhat curiously – at least several of the journals in which scientific articles referred to in-text are published are listed as entries in the Index.] On the plus side, Kesseler & Stuppy’s book Seeds is mentioned in-text, in which case the authors’ names and book title are probably enough information for interested readers to track it down for further information.

However, in several other places, statements are made without any indication of their source, e.g.: “at least 325,000 living species of angiosperms” (p. 58); “around 435,000 land plant species in the world” (p. 136); “7039 plant species that are fit for human consumption” (p. 136); and “Today, 90% of humanity’s caloric intake comes from only fifteen crop plants, with just three – wheat, rice and maize – accounting for around half of our calories globally” (p. 137). Those omissions need to be addressed because they affect the reader’s view of the credibility of the facts reported in the book.

Some words about scientific names

The author uses scientific names for plants, which is always good to see, and common names. But their use is not consistent throughout the book, and the connection between common and scientific names is not always made. For example, no scientific names are provided for neem, Tibetan loquats, and Amargosa niterwort, just their common names [of that trio, only the last has an Index entry, as “Amargosa niterwort”]. For all the many mentions of date palm – especially the Judaean variety, there is no mention of the plant’s scientific name in either the main text or the Index. However, it is to be found under the Image credits on p. 294 where we have “Date palm, Phoenix dactylifera, 19^th century engraving”. Upon first mention of yellow fatu on Pitcairn Island (p. 202), its scientific name is not provided; it is, however, given later, on p. 214 (and is Indexed as “yellow fatu flower (Abutilon pitcairnensis)”). At the other end of the spectrum of nomenclatural exactitude, we have Canna compacta Roscoe for the canna lily on p. 23. Here McMillan-Webster has provided not only the full binomial, but also the Authority (Robert Fagen). Some sort of consistency – e.g. giving both scientific and common name on first mention – would be helpful to the reader.

Some errors to correct?

Any book reviewer risks getting it wrong when commenting upon areas beyond their area of expertise, so I won’t make any comments specifically about seed biology. However, I found two instances where things don’t look quite right to this generalist plant biologist. First, in the initialism NOAA, A is the abbreviation for Administration, not Association as stated by McMillan-Webster on p. 146. Second, the scientific name Coffea canefora on p. 73 looks odd – especially when used in the context of, and same sentence as, Coffea arabica (Arabica coffee). I believe the correct spelling for robusta coffee’s specific epithet should be canephora. Both of these examples, which look like errors, are items that could easily be corrected in a future edition of the book.

More clarity needed

Much of The Age of Seeds contains science that is interpreted and written well for an intelligent but non-specialist audience. And that achievement is rightly to be applauded because getting it right is a tricky thing to do, and is testament to the book cover’s description of McMillan-Webster as a science writer. However, in a few instances that otherwise good ‘sci-comm’, or SciComm (Anna Funk), falls a little short of what’s expected, and has the potential to mislead and misinform the book’s readership. Here are four examples where some additional clarity would be beneficial.

“As a lobeliad it [Brighamia insignis] belongs to the Campanulaceae family, which is the biggest plant family in Hawaii and entirely endemic” (p. 225). As constructed, it appears that the Campanulaceae is a plant family that’s endemic [“a thing that’s only found in a defined physical-geographical place and not anywhere else in the world”] to Hawaii. It isn’t, it’s quite widespread throughout the world and members of the family “grow almost everywhere on Earth except the Sahara, Antarctica, and northern Greenland”. A comma – of the Oxford variety, I believe – between ‘Hawaii’ and ‘and entirely endemic’ appears necessary here to avoid that phytogeographical confusion. But, because insertion of a comma would disrupt the otherwise perfect full-justification of the text, I do wonder if its omission was an aesthetic intervention by the publisher or editor to avoid hyphenating a word, rather than unclear writing by the author?**

The enzyme known as Rubisco [in full, ribulose bisphosphate carboxylase/oxygenase (David Goodsell)] doesn’t have the task of “converting CO₂ into sugar” (p. 149). Rather, this enzyme facilitates the addition of CO₂ to a molecule of ribulose-1,5-bisphosphate [RuBP], and is the first enzyme-controlled step in the complex biochemical cycle of photosynthesis. Subsequent enzyme reactions convert the products of RuBP carboxylation into the ‘sugar’ that is the hallmark product of photosynthesis. Here, an overly-economic explanation of the role of rubisco in photosynthesis has given a misleading impression of the biochemistry of the process and the part played by that enzyme.

“…in a process called oxidation, the ROS [reactive oxygen species (Helmut Sies et al., Nat Rev Mol Cell Biol 23: 499–515, 2022; https://doi.org/10.1038/s41580-022-00456-z)***] steals an electron, ripping it away from where it was happily residing” (p. 246). This wording implies that acquisition of an electron is known as oxidation. As I recall from distant days of undergraduate chemistry, oxidation refers to the loss of an electron (Jim Clark). The flip-side to that bit of chemistry is the process of reduction, which is the gain of an electron (Jim Clark). In the scenario described by McMillan-Webster, by acquiring an electron the ROS has actually been reduced (i.e. has undergone reduction); the molecule from which the ROS acquired the electron has lost an electron, and has therefore been oxidised [has undergone oxidation]. Because the ROS has gained an electron, it (and I apologise for appearing to muddy the waters further by the following) is acting as an oxidising agent, and is an oxidant. I wonder if the confusion in-text has arisen because the important distinction hasn’t been made between an oxidising agent and the process of oxidation? In any event, this issue is easily sorted by replacing oxidation with reduction in the original text.

“…atmospheric levels [of oxygen] reached as much as 35% by the early Permian” (p. 55) [for which statement no source is provided; may I therefore suggest Robert Berner et al. (Annual Review of Earth and Planetary Sciences 31: 105-134, 2003; https://doi.org/10.1146/annurev.earth.31.100901.141329) to cover that point?], “which is 14% higher than current levels” (p. 55). Although I’m no palaeoatmospheric chemist or mathematician, that latter statement looked wrong to me. Surely, with a present-day atmospheric oxygen concentration of approx. 21% by volume (Alan Buis), a late-Carboniferous/early Permian value of 35% is approx. 67% higher than today’s value. I wonder, does the author get her 14% by simply subtracting 21 from 35? If so, it seems a very odd way of expressing the magnitude by which early Permian oxygen concentration exceeds the present day’s. [And, 67% has much more of a ‘wow factor’ than 14%.]

Arguably, those matters probably aren’t that serious in the grand scheme of things, and they shouldn’t affect one’s appreciation for the otherwise great job that the author has done, but they would be worthwhile ‘tidying-up’ in a future printing or edition of the book.

Summary

Taking all of the above into account, The Age of Seeds by Fiona McMillan-Webster is a great book. It is highly recommended for all who want to know a little more about seeds and why they are so important to humankind.

* And one must give a special mention to Carol Baskin in this regard for her lovely definition of a seed, which is “a baby plant in a box with its lunch” (p. 33) – which was originally told to her by one of her college professors, and subsequently shared by author McMillan-Webster with her readers.

** As may also be the case for some of the ‘typos’ I noted on pages 59, 103, 130, 149, 210, 270, and 290 where several sentences are missing very short words. In several instances it looks like their omission is deliberate to accommodate the full-justification used for the text without recourse to split/hyphenated words. As for the Hawaiian endemism example, a legitimate question is whether this is down to the author or the publisher.

*** For more on the role of ROS in seed germination, see Hayat El-Maarouf-Bouteau & Christophe Bailly (Plant Signal Behav 3(3): 175–182, 2008; doi: 10.4161/psb.3.3.5539), and Marcelo Pedrosa Gomes & Queila Souza Garcia (Biologia 68: 351–357, 2013; https://doi.org/10.2478/s11756-013-0161-y).