An Explosion of Flowers

September 12th Emerging from the Avenue on a September afternoon, leaving the darkling shade of the limes and chestnuts and breaking out into warm sunshine and a soft westerly breeze, within a few yards I am struck by two commonplace events of the late summer, coming in quick, unrelated succession, both of which stopped me in my tracks and set me thinking about our long and complicated relationship with flowers.

The first was on a patch of what to most people would be wasteland – a corner of old pasture isolated by a bend in the farm track and left uncultivated for many years. I saw a cloud of winged seed lifting like smoke from the spiked heads of a dense cluster of rosebay willowherb (Epilobium angustifolium). It burst suddenly, as if a smouldering fire had had new fuel tossed on. The seeds were set, poised, ready and waiting to break free; that little breeze just happened to gust through at the right moment. The tall flower heads, so recently a welcome blush of magenta in a world of tired green stain, rocked in the breeze, leaning with it, pointing their charged obelisks so that the wind raked through the laden spikes, releasing like ghosts thousands of downy seeds, each one a hope and a future, desperate for freedom, loaded with ambition. It was a moment to stand and watch.

Some seed caught on grass and nettle heads within a few feet, waiting for a bigger wind to take them on. Much more sailed off into the fields and trees, lifting and swirling, lifting again and disappearing from my view forever. Just like smoke, the seed plume vanished almost as quickly as I had noticed it. I walked on, pondering the mysterious and creative world of flowers and seeds.

A little while later my stroll was rudely and suddenly interrupted by explosions – sharp, snapping cracks like something brittle broken underfoot. They repeated over and over so insistently that they seemed to be trying to make a point. Again I felt obliged to stand and watch. But there was no mystery here; the source was plain to see right at my side.

In the process of making and maintaining a path, a track or a ride, whether by mechanical intent or simply by regular use, man creates a space. To the whole of nature, spaces are opportunities charged with potential. There are hundreds of plants and animals poised, waiting to exploit such chances. Natural clearings are rare, usually the consequence of some disturbance – a tree blowing over, a landslide, an animal such as a badger or a bear digging and rootling around for food, or thrashing about like a stag in the rut, and, of course, man’s perpetual restlessness – exposing the soil to all comers. Spaces quickly fill. The natural world is well supplied with colonising plants that will motor in and take over. Unfairly and often in ignorance, we choose to label them weeds.

Here, commonly scattered across our hills and glens, we have wild broom (Cytisus scoparius), one of the several leguminous shrubs and flowers quick to take up residence in a vacant space. It is hardly surprising that my path is lined by dense thickets of broom shrubbery. Over many years the soils have been exposed by human activities and the broom continually piles in. Now, at the end of the summer, these crackling explosions are the seed pods bursting open in the heat of the day, showering their little, black, pea-like seeds far and wide. If we didn’t keep beating them back the path would close over in no time. In less than two years it would be scarcely visible.

A weed it may be, but broom can be a valuable plant to man and wildlife. Its root nodules fix nitrogen in poor soils; its persistent leaf fall decays into new, more fertile soil and it provides shelter and a home for countless animal species, from tiny invertebrates up to the insectivorous birds – the tits, robins and wrens that colour and enhance my days – among many others that seek sanctuary and food in its shady caverns. Woodcock probe the soft new ground beneath its jungle of ridged stems where roe deer shelter and harbour up during the day. In winter voles and mice feast on the seeds and rabbits gnaw at its nutritious bark, and deer, cattle, sheep and goats will browse on its tart, leguminous shoots. But as well as all this, it is a flowering plant. In May and June the hillsides are lit by the strident yellow and coconut scent of broom and gorse flowers, some years so dense that the whole valley seems to reflect a headily perfumed daffodil glow.

It is harder to argue the benefits of rosebay willowherb, or fireweed, as it is often known. Of the two plants it is perhaps the more deserving of the pejorative ‘weed’, particularly among my generation, who remember the bomb sites of World War II thick with its mauve-pink flowers, for many a symbol of death and destruction and for many others an enduring symbol of renewal. However the human world may choose to view it, as a naturalist I have no doubt that many insects and other organisms enjoy its nectar and its pollen, and caterpillars munch on its succulent leaves and stems. But like broom, its ecological function – that of honest coloniser of spaces, and, by leaf fall and decay, worthy creator of soils – should be value enough for any man.

Willowherb and broom: both flowering plants, both angiosperms. It is sobering to think that our whole existence on Earth both was and still is a direct consequence of flowering plants. Fossil records have enabled us to plot the progression of life, plants and animals, from the earliest stirrings in lake and swamp. The appearance of flowering plants – the angiosperms – comes late on in the unfolding story of life and is the essential springboard for the warm-blooded bird and mammal era, a food source which, in an extraordinarily short space of geological time, was to change everything.

First you have to imagine a world without flowers, without flowering shrubs, without grasses and cereals, without nuts, fruits and berries, without birds and mammals, without humans. This long-vanished ancient world of more than a hundred million years ago was a dull green world of mosses, ferns and primitive trees, for the most part thronging around water, swamps, lakes and marshes because most of them needed ready access to water to reproduce, not by seeds, but by microscopic swimming sperm that could travel to the female cell only through water. Through these early birdless forests and swamps plodded the great, magnificent, cold-blooded reptiles, the dinosaurs.

This was a crimped world of perpetual limitations. The plants were limited by their primitive physiology and the dinosaurs limited by small, reptilian brains kept firmly in check by cold blood, which, like the present-day adders, lizards and crocodiles, required the heat of the sun to operate their instinct-driven lives, and then promptly closed them down again to a motionless, unthinking torpor every time the temperature dropped. This defining limitation permitted only a far slower metabolism than that of any modern mammal or bird. On cold nights the dinosaur world must have been eerily quiet and uncannily still.

For all the remarkable diversity of the tropical Mesozoic age, with its leather-winged, bat-like pterodactyls soaring overhead on ten-foot wings, the colossal vegetarian brontosaurs browsing the swamps, the forty-foot, finned plesiosaurs chasing fish through warm seas, and with a host of ravening predators epitomised by the aptly named tyrannosaurs tyrannising just about everything, it was a ponderous, slow-moving world without song or much colour; a world so alien to the one we have inherited that I find it hard to visualise. Dull greens, browns and greys dominated most life forms and reptile sounds were a cacophony of grunts and growls, hisses and grating screams. The inspirational tonal variety of our own environment, the constant birdsong and diffuse colours we so often take for granted – the blackbirds, robins, chaffinches and wrens and the many flowers of my daily trail – were still millions of years away.

To the present day our native pine, the Scots pine, Pinus sylvestris, is still tied to its wooden seed cone, just like the early pines that had freed themselves from water by the development of wind-borne pollen. The emergence of pollen-producing plants and the now mobile seeds from the primitive cone-flowers of their pine and spruce progenitors was to herald a whole new era of evolution for both plant and animal life. Plants were no longer dependent upon water, nor fixedly restricted to wetland habitat. Their increasingly mobile seeds allowed each plant to expand its range and, by natural selection, experiment with its own destiny, adapting as they went to new and challenging conditions. They could grow wings to be wafted by winds, or by burrs and hooks attach themselves to animals, to be carried over huge distances; they could be catapulted out by mechanical devices like the exploding broom pod, or, ultimately, make their soft casings so attractive to the new order of emerging birds and mammals that they could reliably be carted off in alimentary canals and deposited far and wide. Suddenly there were no boundaries.

This evolution, of course, took many millions of years to perfect, but it can rightly be seen as an explosion – a great bursting out to colonise, dominate and beautify a world waiting for them, a previously silent and unexploited landscape of sands and gravels, bare rock and jumbled boulders. The flowering plants, these highly mobile angiosperms with their astonishing and rapidly expanding subtleties of colour and form – there are over six thousand species of grasses alone – brought with them an entirely new world, a world of wonder and boundless opportunities. Inadvertently they brought us with them too. It is perfectly possible that without flowering plants mankind might never have existed.

As this Cretaceous explosion, some 120 million years ago, was intensifying, so mammals and birds were gradually taking over from the reptiles. The one factor common to the success and progression of both was warm blood, supporting a high metabolic rate. Without constant heat the brain and the body metabolism is severely limited, as it is with insects, which have to scuttle for deep cover every autumn or perish, completely immobilised until the warmth of the sun enables their re-emergence many months later. The brains of both birds and mammals cannot operate without high levels of oxygen and food. The problem facing the emerging mammals and birds – at first only small tree shrews, and lizard-birds, the feathered reptiles of the Cretaceous – was just where this level of high-energy food was to come from.

Angiosperm means ‘encased seed’. It is a concept quite different from the naked seed (the gymnosperm) of the ancient pines. It is a dazzling leap forward. The encased seed is a fully equipped mini-plant ready to go. It is protected, sheltered and fed by its soft, high-energy casing. You can drop it anywhere and it stands a far better chance of germinating than its naked counterpart, which can easily become waterlogged or scorched by the sun. If the naked seed is eaten, the plant is dead. The encased seed lives on. The casing can adapt and evolve, become fatter and fleshier and brightly coloured to attract carriers and pass undigested through intestinal tracts. Thorns, hooks, sails, wings and hard shells can emerge to protect or assist dispersal over many miles; poisons can be built in; mechanical devices like my broom pod can burst out on sunny afternoons.

Throughout the process of dispersal by all these means and many more, a far higher proportion of the cherished seeds lurking within survived intact and poised to germinate. They penetrated every habitat from the sea shore to the mountain top and were successful, far more so than the old order of primitive reproductive mechanisms. The world was turning upside down. Flowering plants were taking over. Yet again the steady, incorruptible miracle of natural-selection-guided evolution had produced a winner; its rapidly exploding diversity forced into extinction many of the primitive and less adaptable plant species of the dull old world of spores and pines and reptiles.

Now broad grasslands could romp unhindered across the Earth’s great plains and uplands, creating savannahs, prairies and montane grasslands; new tree species emerged in the form of great, broad-leaved forests with field layers of grasses and a myriad of bright flowers; between the trees shrubs and creepers rose up from the densely vegetated floor. Most importantly, all of them bore flowers, fruits and nuts supercharged with high concentrations of energy – energy initially designed to nurture the seed inside, but which quickly adapted to attract carriers.

The dinosaurs had gone; the Earth was cooling and mammals and birds were the future. At their feet lay the new, universal, life-expanding benison of carbohydrate-charged flowering plants, theirs for the taking. The fuel and the oxygen were there to support their mental capacity and their galloping metabolic rates.

As the explosion powered ever outward like the ripples from a stone hurled into a pond, a simultaneous new food source and valuable flowering plant tool was rising to the challenge. Nectars and pollens were re-inventing themselves to attract insect and bird pollinators so that the evolution of flowers and insects and dazzling creations such as the hummingbird now became inextricably linked. Insects would never look back, grabbing the new opportunities of this manna with a mind-boggling creativity to which we owe our jewelled butterflies, our honey and bumble bees, our wasps, sawflies and ants, our soldier beetles and cockchafers, our striped hover flies and our exquisite treasury of multi-formed and patterned moths.

In the heat of the tropics and southern hemisphere birds and flowers seem to have evolved together in astonishing leaps of mutual admiration. Honeycreepers, flowerpeckers, sunbirds, brush-tongued parakeets, white-eyes, sugarbirds and even crows hovered, crept, barged, plunged and stabbed their living from obliging flowers desperate to claim birds as their pollinators. Specialised bats, squirrels, rats and mice all attached themselves to the pollen and nectar bonanza. Flowers of every kind joined in with all the gay extravagance of a carnival. Suddenly we had orchids mimicking butterflies and spiders, sprung anthers flicking pollen onto unsuspecting foragers, alluring scents and aromatic oils coating petals to make them still more attractive and a pyrotechnic burst of theatrical colour and design as species after species produced bloom upon riotous bloom in rampant competition for this new and highly effective means of pollination – little wonder Ted Hughes dubbed them ‘pits of allure’.

Now charged with this endless supply of high-energy food, mammal populations also expanded rapidly, producing the great age of the Pleistocene, about a million years ago, with its roaming herds of herbivores: mammoths and elephants, rhinoceroses, bison, buffalo, musk oxen and yaks, horses and asses, camels, llamas and giraffes, sheep and goats, many species of deer, antelope and rodent. Very literally, hard on their heels came the arch-predators: the great felines – sabre-toothed tigers, lions, leopards and pumas; and the dogged herd followers: wolves, foxes, jackals and hyenas; the omnivorous bears hedging their bets, and many more. In the burgeoning forests and jungles the tree-shrew had become a lemur-like creature enjoying the rich pickings of the fruit-laden trees. Monkeys and apes would soon follow in countless variations. Just one of these apes elected to stay on the ground and pick berries. Hominoid ape-men were born into a world rich with fruit, ringing with joyous birdsong and bright with the vibrant colours of flowers.

One of the big problems for the mammals and birds of the Pleistocene is that it coincided with a marked fall in temperature and the onset of glaciation and the Ice Ages. Now stuck with warm blood, it was to be increasingly difficult to maintain body heat and brain power through long winters of ice and no plant growth. Birds had an easier choice: migration. When winter threatened they could gorge with relative ease on the great abundance of summer plants, fruits or insects and then take off to constant food supplies in warmer latitudes. But many mammals could not move fast enough to achieve a great migration and had to find another mechanism for winter survival.

Hibernation meant achieving the necessary physiological adaptations – the ability rapidly to grow insulating coats and lay down fat reserves by dedicating themselves to a period of intense feeding every autumn; thence to bed in a snow den, a nest, a cave, a burrow, or, like the ingenious brown bear, beneath a wood ants’ nest. But it wasn’t to bed, to sleep in any human sense. That would have consumed far too much energy. It had to be a wholesale slow-down of all functions: digestion ceasing altogether; blood withdrawing from extremities to vital organs; heart beats dwindling to the minimum required to prevent the animal from freezing up; breathing barely detectable; dulled brains regulating only those essential involuntary functions. It had to be a specialised heterothermic torpor, but by definition one which rendered the beast utterly helpless, so concealment also had to be highly effective. All this thanks to the high-energy foods constantly supplied by flowering plants. Whether wide-roaming herbivores, ursine omnivores or awesome carnivores, whether grass-, seed-, flesh- or insect-eating birds, that energy – that flower power – was concentrated in the fats of the new-world animals now covering the globe.

Hunter-gatherer men, emerging as we believe in the seasonless tropics of Africa, did not have to worry about hibernation or migration. Theirs was a world of abundance, quite literally a land of milk and honey, to which the generous old gods added meat and fruit. Where better to fuel an expanding brain and the ability to stand upright among tall savannah grasses? How they might laugh with astonishment if they could see the way we use flowers now.

My journal fails to record much more for that day than the explosion of seeds. I walked on, but everywhere I looked I saw more and more seeds spreading or preparing to spread their chances to the winds and waters. The powder-puff heads of dandelions, hawkweeds and thistles strove to emulate the willowherb. Lesser burdock locked its ferocious, Velcro-hooked balls – maddeningly difficult to remove – onto my socks and trousers. The vermillion hips of straggling wild roses dotted the rough edges beside the burn. Ash and sycamore keys in gaolers’ bunches rattled in the wind. On the surface of the loch the floating seeds of alders bobbed and jostled among those of rushes, Juncus, against the dam. In my pocket was a glossy conker – one of the first of the season – I had prised from its fleshy, spikily armoured casing under the horse chestnuts in the Avenue.

At the water’s edge the rowan trees were laden with ripening berries, berries that would feed tens of thousands of migrating thrushes – fieldfares and redwings – on their chattering way south to Africa for the winter; berries which, as soon as they were fully ripe, would be gobbled by pine martens too. Soon the paths would be punctuated with vulgar ejaculations of semi-digested fruit in soggy little red piles, almost as though the martens were using the fruit as a purgative to effect a good clear-out. In both of these cases the seeds will be undamaged, their work still to be done, often to be carried off by mice and buried – a secondary dispersal, complete with being planted to boot. The fieldfares and redwings will unwittingly scatter theirs far and wide, each seed ejected in a ready-formed bubble of excrement fertiliser high over the moors and mountains like scatter bombs ready to fire. Fuelled up on worms, caterpillars, snails and bugs in Scandinavia, these thrushes have gathered in vast flocks to catch an easterly wind across the North Sea because that food supply is closing down for the winter. Here, most conveniently placed, the wild rowans, as well as the hollies and cotoneasters of our gardens, will fuel them up again for the great push south.

I drew a warming existential comfort from this thought. The scarlet flesh of our rowan berries at the loch linking up with Scandinavian snails to provide the energy surge for one of the great bird migrations of the northern hemisphere, spreading and creating a bright, new generation of rowan trees as they go – the inspirational, boundary-less interdependence of all living things.

But there is one more extraordinary twist to the man story of flowering plants. Our hunter-gatherer was successful – too successful. With spear, axe and fire he began to change and control his habitat. He learned to hunt in gangs, to set traps, to herd his lumbering prey species to their deaths. Probably by accident he learned to burn their flesh in the fire, making it easier for his fruit-designed stomach to digest. He prospered and his numbers grew. He cleared forest and drove those animals he needed for furs and meat to the brink of extinction; some never recovered. The cave bear, the giant red deer (Megaceros), the woolly rhinoceros and the mammoth were too slow to adapt, too big and cumbersome to hide, and, in the case of the cave bear, too vulnerable in hibernation. Caves were in short supply and always bound to be explored by early man. With the demise of the great herds, some of their primary predators also perished, the dire wolf and the sabre-toothed tiger fading away altogether, and the global range of the lion and the tiger, ever tied to their prey, began to shrink.

In those areas of the world where mankind was most populous he was now at risk of hunting himself out of meat. If prey species’ populations crashed, he crashed with them. He needed another, more predictable source of energy. It was the flowering plant that got him out of the primeval forest and up onto two legs, and it was to be the flowering plant that was about to rescue him again.

Those same grasses that had sustained the great herds of prey were still there, still flowering and still producing a great profusion of annual seeds. It was to take only one imaginative human to realise that in his own time and his own place he could plant those seeds to suit his needs and the world would change again. From a handful of grains of rice or wheat, of barley or wild oats or maize, would spring all the wealth and cultural diversity of the modern age. Our surging populations, our great cities, our terrifying machines and weapons, our spiralling knowledge, our religions, our medicines, our dreams and our vaulting ambitions would all spring from and come to depend upon those few carefully nurtured seeds. The world we have created, our world, was gifted to us by an explosion of flowers.