To my way of thinking, there are not enough books written for a general audience about the science of plants. But why do publishers insist on telling us on the jacket of nearly every one of these rarities, including Peter Thompson's, that the lives of plants are hidden and secret? What's secret about a sex life advertised with gaudy blossoms arrayed with protuberant reproductive organs and scented like a tart's parlour? By comparison with a rose or a hibiscus, surely even the sexual blush of a baboon's bottom looks coy.
What is indeed hidden, and is ably revealed by Thompson, is not the life of plants, but the history of how plants taught us farming, genetics and ecology. In an engaging introduction, he explains that seeds are the basis of settled agriculture and hence the origins of cities and urban civilisation.
True enough, except that Thompson also tells us that maize cultivation is an exception, not having spawned any real cities in North America. This will be news to the Mexicans who consider themselves North American, or possibly these days even consider North America Mexican. Aztec, Mayan and Olmec cities all depended on maize cultivation and the collapse of the Mayan centres was probably caused by environmental change undermining their agriculture. Seeds make and unmake cities.
The role that peas played in Gregor Mendel's discovery of the laws of inheritance is well known, but was he just lucky in his choice of material? So many plant characteristics he might have chosen to study do not segregate in the convenient manner that revealed Mendel's Laws. I have always wondered about this, and Thompson uncovers the answer. It seems more than likely that Mendel was set on the right track by a German translation of a paper by Thomas Knight, the British farmer and gentleman scientist who reported his experiments on breeding peas in the Philosophical Transactions of the Royal Society in 1799.
Another hero of seed science feted by Thompson is Nikolai Vavilov, the Soviet geneticist who discovered the huge genetic diversity in local populations of crop plants around the world. This diversity is the source of new genes for traits such as pest and drought resistance that is the basis for breeding new crop varieties.
Vavilov's global travels and knowledge of crop genetics enabled him to pinpoint the likely geographical origins of many of our crops, including the fertile crescent in the Near East where European agriculture began about 10,000 years ago. Tragically, he was a victim of Stalin's purges. Genetics was deemed by Stalin to be a reactionary obstacle to the unlimited biological improvements in every sphere that communist society would inevitably bring about by sheer force of political will.
The politicised rivalry between nature and nurture as dominant forces in human affairs continues, but the environmental adaptations of seeds show how simplistic and misguided such a dichotomy is.
Thompson provides an elegant example via his research on the germination characteristics of bluebell seeds. We know this species as a woodland plant, but this is not the habitat in which it evolved. Bluebell seeds germinate in autumn, triggered by falling temperatures. This is a characteristic of Mediterranean plants, not normally the denizens of northern woods where falling temperatures often herald seedling-killing frosts. The risk pays off because the early bluebell seedling catches the light, should the weather occasionally allow it to survive the winter. But bluebells, like many plants, do not permit all their seeds to germinate at once. A fraction is held back as a failsafe for the mother plant. Thus the evolved, inherited germination strategy of seeds responds subtly to the environment, conferring surprising flexibility upon the plant. Just one of the gems of seed lore hidden in this admirable book.
Seeds, Sex and Civilization: How the Hidden Life of Plants has Shaped our World
By Peter Thompson
Thames and Hudson, 2pp, £19.95
Published 4 October 2010