When plants go to war!

Plants go to war: A botanical history of World War II by Judith Sumner, 2019. McFarland & Co.

Lest there be any doubt at the outset, this blog item is an appraisal of a book that looks at the role of plants in wartime: It doesn’t deal with the myriad marvellous ways that plants defend themselves from attack by herbivores, etc. or invasion by microbes. As fascinating a tale as that is, the wartime involvement of plants, as documented by Judith Sumner in When plants go to war, is arguably even more interesting – from a plants-and-people point of view at least. Advertised on its back cover as “the first botanical history of World War II (WWII, which lasted from 1st September 1939 until 2nd September 1945)” – a claim I have no reason to doubt * – it is therefore an ethnobotanical account of a very important event in the 20th Century.

Well balanced geographical coverage

Knowing that the author is an American-based botanist – and considered a “local botanist” by Discover Central Massachusetts Dot Org, and that one of her previous book’s was entitled American Household Botany, I was concerned that Plants go to war would be rather US-centric. However, it isn’t, and due consideration is given to such areas as England **, Europe, Russia (the Soviet Union or USSR as it was then), Japan, Germany, the USA, and both the Pacific and European theatres of war ***.

Encyclopaedic coverage..?

Plants go to war consists of 12 chapters in approx. 320 pages that deal with topics such as: digging for victory; diet and cookery; agriculture at war; medicinal botany; forestry, timber and wood; oils, resins and rubber; and fibres. It is completed with a Bibliography, Index, and extensive Notes for each chapter. There are great facts on every page – and usually more than one: This book is a veritable gold-mine of useful botanical insights, and figures. As might be expected, its taxonomic coverage is primarily of vascular plants (largely angiosperms and conifers), but other taxa do get a mention – e.g. sphagnum for wound dressings, and algae as the source of agar. Although illustrated throughout, it’s only in black-and-white, but does feature lots of examples of WWII posters and photographs, and drawings of selected plants. Plants go to war appears to be as comprehensive a catalogue of plant exploitation by humans during that devastating global conflict as one can probably imagine – and wish for.

Food, glorious – but heavily rationed – food!

Until I read Plants go to war my knowledge of WWII was largely from a British perspective. I was therefore familiar with the notion of digging for victory in the UK, but had no idea that there was a similar initiative in America. It was therefore quite a revelation to read that, by 1944, 44% of all food in the US was grown in 20 million ‘victory gardens’, and that those gardens can be traced back to so-called ‘relief gardens’ of that country’s Depression era. Clearly, digging for victory was a big feature of civilian wartime life on both sides of the Atlantic. And that’s an important message of Plants go to war; humanity’s relationship with plants affected both the armed combatants and those on the ‘home front’.

Chapter 2 – approx. 23 pages – is largely devoted to the UK’s Dig for Victory campaign, which campaign was also adopted by British colonies such as Australia and Canada. Sumner goes into considerable detail about the propaganda surrounding victory gardens which made much of the notion of turning allotments into battlegrounds that paralleled the war itself – emphasising that battles on the home front were as keenly fought as those on the front line.

Interestingly, Germany had its equivalent Schrebergarten, which had been around since the since the 19th Century. They were productive vegetable gardens located away from city centres. Considering the fact that several German city centres were heavily bombed by the Allies in WWII, one can only wonder if such rural siting was an example of prescience or just good luck.

Food is the subject matter of the first 6 Chapters amounting to 160 pages, or half of the book’s main text. And quite rightly so; an army may march on its stomach, but it’s the people back home whose hard work and sacrifices provide the botanical calories and nutrients that fill those combatants’ bodies. And, as a US Department of Agriculture slogan had it, “Food will win the war and write the peace”.

Distorted plant anatomy…

As useful to mankind as the products of plants are, understanding why that may be so is fundamental to a better appreciation of how they can be exploited by humanity. That is underlined by Chapter 9 “Forestry, Timber and Wood”, which is a great advocate for the importance of knowledge of wood properties and matching species to specific uses. Sadly, though – and is often the case in times of conflict – such basic knowledge can be subverted to a more sinister purpose. Thus, intimate knowledge of conifer wood anatomy led to German artillery shells being timed to detonate near the tops of trees in forested areas, such as the Hürtgen Forest. This caused the tree trunks to shatter and scatter high speed shards and splinters of wood that caused great harm to the enemy****. By way of retaliation, Allied forces exploited their knowledge of the flammability of conifer wood resin to set such trees alight using napalm in attempts to force German troops from their hiding places in the soft-wooded Ardennes region during the Battle of the Bulge.

Lateral thinking used to good effect

Sumner uses a dodge I’ve also employed – lateral thinking to bring in even more plant-relatedness to the subject. Hence there is much mention of silk because, although it’s an animal-derived fibre from caterpillars of the silk moth, they feed exclusively on the leaves of mulberry. So, too, there’s a big mention of nitrogen fertiliser made from ammonia produced by the ‘artificial’ HaberBosch Process, because Sumner tells us that the hydrogen forthe reaction comes from methane, a breakdown product of cellulose, one of the most famous plant products of all.

And, there’s lots of mention of chemicals derived from coal, via coal tar. Is that stretching the point re botanical credentials? No, this is legitimised by the fact that coal is a “high carbon sedimentary rock” made from Carboniferous period vegetation” (p. 209). Such lateral thinking underlines even more emphatically the plant-dependency of WWII endeavours – and also mimics the inspirational and creative uses of plant products themselves during that period of global conflict and uncertainty.

Good pedagogy

From a pedagogic point of view, there is much to commend in Plants go to war – which emphasises its potential as a textbook for the subject. For instance, it contains some repetition – both between and within Chapters. I suspect that this is inevitable in such a wide-ranging book whose topics can be organised both horizontally and/or vertically. But readers may not read all the chapters, in numerical order, so there is some need to explain terms again to ensure that the reader who may wish just to dip into the odd chapter understands the relevance of a specific topic. Plus, such a practice can be considered good pedagogy in terms of its reinforcement or recap of important messages.

Illustrations come complete with extensive captions, whose words are also repeated in the text itself. Is this unnecessary repetition? Maybe, but I think it’s much better to consider this to be an example of good communication – in ensuring that the illustrations stand on their own without recourse to the text.

There are abundant in-text Numbers which relate to Notes accumulated at the end of the book by Chapter, and which refer the reader to items that are fully cited in the Bibliography. The interested reader can therefore find out more about the information presented in Plants go to war. Unfortunately, not every fact is referenced in this way, and quite a lot of what one might consider to be ‘general botanical information’ is unreferenced, e.g. the Carboniferous Period and the biology of coal-formation (first paragraph on p. 248). Whilst such material may be deemed to be common knowledge to botanically-minded readers, that might not be the case for the more generalist audience the book is surely hoping to attract. Arguably, an opportunity to enhance the public’s ‘botanical literacy’ is thereby missed. For a book with a 2019 publication date, it was a great pleasure to note how up-to-date were the references cited, e.g. the mention of the WWII battleship Tirpitz and the record of its smokescreen activities recorded in tree rings of local pine trees.

But, what is there in Plants go to war is well-written and a fascinating story – that was both a joy and a revelation to read – is presented. One touch that was noticeable and much appreciated was the well-crafted writing structure, particularly with paragraphs that started with a short sentence or claim as a statement of fact, which is then developed or justified in the rest of the paragraph. It was really nice to see this.

It’s very good, but there’s still room for improvement

Plants go to war is a great book, and there’s a lot that is really good about it. However, as a book about plants by a botanist, and particularly one that can help towards educating the public about plants and improving their botanical literacy, there were a few items that I feel need to be challenged – and corrected, or at least clarified.

There appears to be confusion between C4 photosynthetic metabolism – as found in such plants as maize and sugar cane – and the CAM (crassulacean acid metabolism) variant of photosynthesis on p. 67. Specifically, Sumner states that C4 photosynthetic sugar cane closes its stomata during the day, but opens them at night when carbon dioxide is absorbed for reuse in photosynthesis. As far as this botanist is aware, night-time closure of stomata is something that CAM plants do, but it’s not a feature of C4 photosynthesis in, or the general biology of, sugar cane.

On pages 39 and 150 Phytophthora infestans, the causative agent of late blight of potatoes, is described as a fungus. It’s not a fungus, but an oomycete. Whether it was still considered to be a fungus during WWII I don’t know, but I would have thought it best practice to use up-to-date taxonomic information for this organism.

On p. 108 Sumner talks about the “sixteen-petal flower” of chrysanthemum. Chrysanthemum is a member of the Asteraceae (or daisy or sunflower family, or Compositae) whose ‘flowers’ are actually composite heads of many, massed individual flowers. The structures that, to the unknowing eye, look like the petals of a more typical single flower are the strap-shaped ligules of the flowers on the outside of the massed group of flowers, the so-called ray florets.

Despite the equivalence that is strongly implied on p. 247, cork cambium is not the same as phelloderm. Phellogen is a synonym for cork cambium; phelloderm is the name of the tissue produced to the inside of the cork cambium.

Tyloses aren’t “polysaccharide plugs” as stated on p. 284. Rather, they are “balloon-like swellings or projections that fill the vessels”, or “outgrowths from xylem parenchyma cells that grow into the lumen of tracheary cells”.

And for some sort of completeness, though it’s not a strictly botanical matter, there appears to be an issue with the statement on p. 46 that “a single candle consumed negligible levels of carbon dioxide”. Whilst I’m prepared to accept that is the case, I suspect what was intended was to stress the reassuring fact that a single candle consumed negligible levels of oxygen.

Was Fritz Haber a pacifist?

On p. 108 Sumner describes Fritz Haber, co-developer of the Haber-Bosch process for ammonia manufacture, as a “pacifist German chemist”. It would have been easy to take that at face value and accept it. But, when I read that I had doubts – from something half-remembered from having read or heard previously – that led me to question this statement, and decided to do a little digging. As I suspected, I find there are many ‘misgivings’ about Haber’s character from his chemical work. True, the Haber-Bosch process has been hailed as “the most important invention of the twentieth century” (Vaclav Smil, 1999, Nature 400: 415; https://doi.org/10.1038/22672), Haber and Bosch have been described as the “most influential persons of the 20th century”, and its discovery led to Haber gaining the Nobel Prize for Chemistry in 1918 “for the synthesis of ammonia from its elements” (and Bosch being awarded the Nobel Prize for Chemistry in 1931 “in recognition of their contributions to the invention and development of chemical high pressure methods”, along with Friedrich Bergius).

But, Haber’s Nobel distinction was considered somewhat controversial. Some of that controversy relates to the fact that ammonia made by Germany using the Haber-Bosch process during World War I (WWI) was used for the manufacture of explosives, which killed people rather than fertilised agricultural fields to increase food yields that could help to feed people and keep them alive. Much more controversy resulted from Haber’s research during WWI where he worked on developing chlorine gas as a weapon of war, and earned him the unenviable title of “the father of chemical warfare”. Not only are such weapons abhorrent, their use was in contravention of the Hague Conventions that prohibited use of chemical agents in battle. Their development, whilst at odds with any claims to pacifism, are consistent with the view that Haber “was a fanatical patriot, and thought that a scientist should do everything in their power to help their country, especially in time of war”.

It is known that Clara Immerwar, Haber’s wife – also a PhD chemist – was a pacifist and opposed to his wartime work on poison gas, which to her was a “perversion of the ideals of science”. Clara was so appalled by Haber’s researches that she took her own life on the night her husband celebrated his promotion to captain after returning from the site of the first successful gas attack. Seemingly undeterred by that dramatic turn of events Haber was directing more gas attacks the day after his wife’s suicide.

In light of the above, was Fritz Haber a pacifist – one who has a “commitment to peace and opposition to war” or who considers that “the idea that war and violence are unjustifiable, and that conflicts should be settled in a peaceful way”? Apparently not.

Auschwitz, or Oswiecim?

“Human bones from the concentration camp at Oswiecim in Poland were collected and … processed … into superphosphate” (p. 162). That statement is incredibly shocking on many levels, not least because the superphosphate was subsequently used as a fertiliser for plants as it provides phosphorus and calcium in particular to help their growth. The statement is also intriguing because Sumner here uses English version of the Polish name – Oswiecim – for the place that is more infamously known by its German name of Auschwitz, the site of one of the most notorious of all the Nazi concentration camps of WWII. In Plants go to war, Auschwitz is mentioned by name on at least four occasions, and Oswiecim only once. On none of those occasions is there mention of the connection between the name Oswiecim and the Nazi death camps of the Auschwitz complex: Why? Whilst the author may know that the two names are effectively synonymous, I think it would have been a useful service for readers, who may not know this, to have it clearly stated.

I don’t want to dwell on the item here and in the immediately preceding two sections because overall Plants go to war is a great book. However, as a potentially important botanical educational text it is equally important that Plants go to war is as accurate as can be. Hopefully, these matters will be addressed and corrected in a future edition – which there must surely be as more information comes to light on this fascinating topic!

Some things you will learn…

It is not my intention to give away all of the book’s secrets – with one or more on every page that would be to reproduce the book! But, I thought it would be useful to share some of the interesting snippets of information I gleaned in my reading of Plants go to war: The use of coconut water as a substitute for blood plasma; that chlorophyll can be used to kill bacteria – but was too unstable for effective medicinal use…; dying white cotton bandages green, so they were less visible in a jungle setting; the ‘solanoscepticism’ of Americans regarding tomatoes, consumption of which was apparently not really taken up until the mid-19th Century; demand for ammonia in manufacture of munitions reduced the per centage of nitrogen in NPK fertilisers, which helped to encourage other ways to fertilise crops; “At the start of World War II, about half of all pharmaceutical drugs included botanical derivatives in their formulations”, etc.

One of the book’s most curious stories concerns onions and the British. I was intrigued by Sumner’s suggestion that onions were viewed with suspicion by the British at the start of WWII, being ‘foreign vegetables’ with a persistent aftertaste. I was then amused to read that, presumably once they’d been accepted as a desirable food crop that could enhance bland vegetable dishes, onion bulbs were particularly susceptible to theft – which plant-pilfering was on a par with looting from bomb sites and treated with harsh punishment. Scarcity of onions was a major issue because their import to Britain – 90% of that country’s onion demands were met from abroad – was severely reduced by the activity of German U boats that attempted to sink ships taking supplies to the UK. That scarcity of onions was underlined by their being awarded as prizes in competitions(!). The wartime travails of the onion are just one example of many in the book of how attitudes to particular foodstuffs were changed by WWII.

Aside from the practical aspects of plants-people interactions, there are also the more subtle ones, which Sumner recognises and includes. For example, the capacity for plants and flowers in particular to lighten and brighten one’s mood and improve one’s mental health – i.e. help to boost the morale of those on the home front – led Winston Churchill (the UK’s wartime leader) to remove the cancellation of trains from Cornwall bringing flower shipments to urban areas that had been put in place in late 1942. Sumner also includes a comment about the depressing effect on morale on German troops on the Eastern Front when they first saw the kilometres of sunflower fields in Russia; only then did they realise how vast Soviet Russia was and therefore how formidable a prospect was the Nazi regime’s attempt to conquer that nation.

The resilience of the people caught up in WWII is matched by the imagination and creativity with which they used plants and plant products, or whatever was to hand to help them produce more of the war-winning plants. Thus, it was interesting to read that the moat around the Tower of London was converted to allotments, and bomb craters were turned into gardens. With stories about the diet and imaginative ways to stretch the food that was available and reduce waste, one does wonder how many of the wartime uses could benefit communities nowadays – nominally in peace-time – and help us to win modern battles against obesity, global malnutrition, climate change and other environmental destruction…

Increase your word power

Readers will also have the opportunity to learn some new words. New ones for me included: Autarky (pp. 1, 103), which I now know means ‘self-sufficiency’. Although this is clearly an important concept for war-beleaguered states, it was a bit of a shock to be confronted by this unknown-to-me term right at the start of the book! Canned hominy (p. 113); hominy is corn kernels, canned hominy is that foodstuff … in a can. And majolica (p. 320); “Majolica – also spelled Maiolica – is the beautiful ware prepared by tin-glazing earthenware and firing it a second time”.

It’s uncomfortable reading in places

As a Botanist I was profoundly disappointed to learn of the role played by plants in the synthesis of Zyklon B, the infamous compound that generated the cyanide gas used to kill inmates of Nazi death camps. Apparently, when sugar beet is processed at temperatures in excess of 1000 oC it releases hydrogen cyanide (HCN) which was then used in the manufacture of Zyklon B.

However, an important related fact, which is not mentioned in Plants go to war, is that Zyklon B was developed from a compound invented as a pesticide by Fritz Haber, of Haber-Bosch Process fame [see Was Fritz Haber a pacifist? section above], shortly after the end of World War I*****. In a cruel irony, Haber, who was Jewish but renounced his faith to become a Lutheran possibly to appear more German, had unwittingly created the poison that would be used to murder so many Jews – including members of his own familyand others during WWII.

Still not convinced?

For a flavour of the book, why not visit the author’s blog for an item by author Sumner on “Medicinal Plants During World War II”?


Channelling my ‘inner Craig Revel Horwood’, I can sum-up this book in three little words: A may zing. There are some books that, when you’ve heard about them, you just have to get hold of and read. Plants go to war is such a book: Read it!

* The other ‘plants at war’ book I’m aware of was reviewed on Botany One by S Suresh Ramanan. That tome – Eran Pichersky’s Plants and Human Conflict – looks at the involvement of plants in human conflicts more broadly than WWII.

** ‘England’ – which, being charitable, I will assume is used by the author as shorthand for the United Kingdom, which includes the countries of England, Wales, Scotland, and Northern Ireland.

*** However, from a geographical point of view one must question Sumner’s statement on p. 105 that Switzerland is “surrounded by Germany”. It isn’t: “The Swiss Confederation is a landlocked nation state in Central Europe. Countries bordering Switzerland are France to the west, Germany to the north, Austria and Liechtenstein to the east and Italy to the south”.

**** This is somewhat reminiscent of maritime battles where the splintering of ships’ timbers when blown apart by cannonballs for example caused death and severe damage to the seafarers.

***** … or his work is cited as leading to Zyklon B’s development [e.g. here, here, and here], which formulation was created from the original Zyklon. For more on Fritz Haber’s story, try Daniel Charles’ biography Master Mind: The Rise and Fall of Fritz Haber, the Nobel Laureate Who Launched the Age of Chemical Warfare.

Nigel Chaffey

I am a botanist and former Senior Lecturer in Botany at Bath Spa University (Bath, near Bristol, UK). As News Editor for the Annals of Botany I contributed the monthly Plant Cuttings column to that august international botanical organ - and to Botany One - for almost 10 years. I am now a freelance plant science communicator and Visiting Research Fellow at Bath Spa University. I continue to share my Cuttingsesque items - and appraisals of books with a plant focus - with a plant-curious audience. In that guise my main goal is to inform (hopefully, in an educational, and entertaining way) others about plants and plant-people interactions, and thereby improve humankind's botanical literacy. Happy to be contacted to discuss potential writing - or talking - projects and opportunities.
[ORCID: 0000-0002-4231-9082]

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