The best books on Plants

The Emerald Planet by D J Beerling.

This is a book by somebody who studies plant fossils and their role in life on earth. I reviewed this when it came out and here’s what I wrote: ‘Botanists carry a chip on their shoulders. Their relationship with the zoocentric world is like that of a perplexed parent of a sullen teenager who refuses to acknowledge that his very existence depends upon them. We don’t acknowledge the importance of plants. Beerling believes that too many people think that plants are a pretty dull chapter in the history of life and one that can be skipped. He complains that Richard Dawkins all but ignores plants in his study of life and Beerling’s resentment is palpable.

The Emerald Planet is a serious talking to about why plants must not be ignored.’ I agree with him that plants are grievously overlooked, because no life on earth would exist without them. It’s all either plants or something that eats them and this book basically explains plants’ place in earth’s history. It explains, for example, how the oxygen in the earth’s atmosphere came from plants, the role of plants and trees in the carbon cycle and, of course, we all understand that carbon has a role in controlling our climate nowadays. So, if you want to know about that then this is the book.

What is the plant’s role in the earth’s history?

Basically, the early earth had no oxygen in its atmosphere, and when the first life emerged, microbial single-cell stuff, oxygen was poisonous to it, because it interfered with important biochemical reactions. What plants did, or bacteria in the ocean did, was evolve a way of harnessing the carbon in sunlight and liberating oxygen in the process. Over time what happened is that oxygen built up in the atmosphere and you can see this in the fossil record. There are geological strata called red beds, iron-rich deposits. They are red because the iron rusted on exposure to oxygen, so there’s a point in earth history where you can see the oxygen appear because the iron in the soil rusted.

So, if it’s not rusted there was no oxygen?

That’s right. If you put an iron nail in an oxygenless atmosphere it won’t rust, but in ordinary air it will.

The book I’m talking about now is Eating the Sun: How Plants Power the Planet by Oliver Morton. This book is basically about the discovery of how photosynthesis works. So, photosynthesis is turning carbon dioxide, water and sunlight into something useful to both plants and to us: sugar and oxygen. The process of photosynthesis evolved in these things called blue-green bacteria three billion years ago and this is the foundation on which everything else has been built by evolution. It’s the same process in those blue-green bacteria and algae in the sea and the plants on land – they all use a version of the process that evolved three billion years ago. It’s an amazing story and this is why botanists feel hard done by because you think: well, actually, it’s interesting this stuff, and we depend on it – so don’t ignore it! The blue-green bacteria, by a process that we are still unravelling, passed the genes that make the photosynthetic machinery on to other organisms and that one aspect of evolution gave rise to such a great diversity of things that are green. I am sitting here in my study at home and I can see a palm and cacti and other plants and the relationship between these plants is ancient but they are all green and they all use the same way of capturing energy. That’s also true of the algae in the sea and in your fish tank.

Is this a book I could easily read?

This is a very readable book, less technical than The Emerald Planet. It does get into biochemistry but you can skip bits! He makes the story personal by talking about the lives of the people who discovered photosynthesis, or, rather, how it works. There is a whole series of people and he only chooses some of them. He tells the story as a narrative and then he goes on to talk about the kind of stuff that Beerling talks about, the red beds and things like that.

The Secret Life of Trees by Colin Tudge.

This is basically a tree-lovers’ book and it’s a bit of a catalogue in a way. He talks about what makes a tree a tree. A tree is a woody plant with a trunk, which is a pretty obvious definition, but that way of being a plant has evolved many times. So trees are not, evolutionarily speaking, one thing. They are a group of things with different evolutionary origins. For example, pine trees and oak trees have quite different origins. They are seed plants, but they acquired the habit of standing up on a long tall trunk independently of each other. Their ‘treeness’ evolved independently. Palms are a good example – they evolved the habit of standing as they do quite separately from oak and pine trees. It’s a different way of being a tree. The interesting thing about palms is that if you plant an oak seedling after five years it is five centimetres in diameter, after ten years 20 centimetres and so on, but that isn’t the way palms grow. Palms don’t get fatter as they get older. A baby palm sits on the ground accumulating leaves until it’s fat enough to grow upwards. Once it begins to do that, you’ll see that a baby palm of a metre high has a trunk that will ultimately support something that is ten metres high. The reason for this is that they’re not built in a way that allows them to get fatter, because the trunk is made of the bases of old leaves. The coconut germinates and lots of leaves accumulate like a huge rosette and only when it’s got enough of those can it start to grow upwards. But, an oak tree starts off slender and gets fatter. These are completely different evolutionary tracks. So, this book is about different ways of being a tree, all the trees in the world in their different groups – trees without flowers, conifers, magnolia (which is a relatively primitive early tree), and so on. So, if you like trees, and lots of people do, this book is for you. It has done very well.

Why did trees grow upwards?

We can’t really know because it happened a long time ago, but it happened after colonisation of land by plants. Life evolved in the sea and the earliest photosynthetic fossils are of things that lived in shallow water. Eventually, plants colonised the land and there is a little tiny fossil, about the size of a moss, that is the first land plant. But as competition among plants grew, trees evolved, almost certainly driven by the simple fact that the highest plant gets most of the light.

Plant by Janet Marinelli.

This is a coffee table book but it’s a very, very good coffee table book. It’s produced by Kew Gardens and it’s just got fabulous pictures, full-page spreads of plants and pretty much everything you might want to know about plants in general. There’s a section called ‘The world of plants’ about their evolution and what they do for us, a section on weeds, and if you love plants this is a fun book to read. It’s quite dense. It’s not a children’s book by any means and it deals with conservation and global warming and it’s full of pictures and it’s very nice! Plants with bulbs, climbing plants, bamboos. Everything.

Which are your favourites?

I rather like palms.

Are you surrounded by palms?

I wish! I do have a greenhouse with a few in but if I had to choose one plant which I haven’t seen in the wild, sadly, it would have to be the double coconut. This thing lives on just two islands in the Seychelles and it has this massive seed, the biggest in the world, and, unusually for plants, this palm has separate males and females. The poor females are so stunted by having to carry these massive seeds in their crowns that they often lose the tops of the trees in storms and things. It has a fascinating life history that you can read about in my own book on seeds.

Book five, Feeding the Ten Billion by L T Evans.

This is where it gets serious. It is estimated that we currently have seven billion people on the planet. The UN estimates that the population will continue to grow to at least nine billion, maybe ten billion. If you just think for a moment what that means – when I was born, 50 odd years ago, there were about two billion people on the planet. So, within my lifetime it’s gone from two to seven and certainly before my children are my age it will be nine or ten. How are we going to feed these people? That’s what this book is about. It goes through each billion, one at a time. So, between 8000 BC and 2000 BC the global population moved to 50 million. That’s a global population less than the current population of Britain. So, in those days it would be very unusual to bump into anybody who wasn’t immediately related to you. Cutting to the chase – how are we going to feed ten billion. What Evans says is: ‘To feed the ten billion without increasing the arable area will require an average yield of about five tons a hectare, beyond that reached by Europe and North America.’ His guess is that it will be done, but I’m not so optimistic. He thinks it will be done because there have already been, up to now, amazing increases in agricultural yield, because of plant breeding combined with the industrialisation of agriculture. He says that the need to do this is so great that, provided we invest in the science and technology, it can be done. He admits it’s something of an act of faith though.

Do we really think the population will grow that much? Maybe we’ll all be wiped out before it gets that bad.

Well, that would be even worse! I’ve got a book behind me on the shelf called Our Final Century by Martin Rees, the Astronomer Royal. So, obviously, if we don’t manage it then, I suppose, that solves the problem. But otherwise it’s inevitable we’ll get to nine billion. For example, half the population of Egypt is under 15. They’ll grow up and have families. You only have to do the maths, as they say. Evans thinks it’s technically possible to feed them, but obviously there’s a lot of politics involved and so on. It’s a sobering book to read and it raises all kinds of questions. We have to ask ourselves what technology would be involved and, if it was necessary to use GM technology, could we really afford to say no? Evans concludes that we’ve managed to produce more and more food and as long as we use science to do this then we could feed ten billion people. You could regard that as good news. But how much of nature would be left if we use most of the planet to grow food? We’d have to expand the land area being used to grow food. Plus, if we’re going to use biofuels some of that land area will have to go into running our cars. What will be left of wild nature if we fail to exploit to the full all the land we’re already using? These are tough choices.