A Wonder World of Plants In A Wonder World of Isolation

by Adele A. Wilby

Apple orchard in bloom in April, 2020

After assuming the mantle of a ‘vulnerable’ member of society and with many of my contacts temporarily closed off to me consequent to the British government’s public health policy of ‘social-distancing’ in place during this coronavirus pandemic, time is something I have plenty of. Thus, I took a tour of the unread books on my sitting-room table. Three books screamed out at me that they had been waiting for some time for me to pick them up and read them, but they had been constantly pushed to the end of the queue in preference to more urgent others that were later arrivals. Now I have time for them; it was their turn to be read, and they were worthy of the attention. The complexity and beauty of plants are the themes of these three books: Jonathon Drori’s Around the World in 8o Trees, Stefano Mancuso’s The Revolutionary Genius of Plants: A New Understanding of Plant Intelligence and Behaviour and his The Incredible Journey of Plants.

Like many of us on this planet, apart from an aesthetic appreciation of plants and our favourite trees and flowers, I have not given too much attention to what actually constitutes a plant. Had I known that, according to Mancuso, 80 percent of the earth’s biomass is taken up by plants, I might have given these inhabitants of the planet greater thought. Likewise, I was astounded to learn from Drori that there are at least 60,000 distinct species of trees sharing this planet with us: understanding more about plants was clearly a necessity.

Mancuso, a plant neurobiologist comments in The Incredible Journey of Plants that: ‘We will never be able to understand plants if we look at them as if they were impaired animals. They are a form of life that is different, neither simpler nor less developed, than the animal form of life’. That plants are to be appreciated and valued on their own terms is a tall order for those who see them as, well, just plants at the whim and mercy of the likes and dislikes of human beings. But we quickly come to realise through his books that Mancuso has a point: plants are complex life forms of intrigue and great beauty and part of the amazement and appreciation of these life forms stems precisely from the ‘difference’ in their structure.

Unlike animals, plants are not mobile, they are ‘sessile’, ‘rooted’, in a place, but they nonetheless move. Likewise, they learn, which requires memory, a concept Mancuso realises is contested when applied to plants: plants do not have a centralised organ, a brain. But in the absence of a brain, how do plants manifest ‘intelligence – the ability to learn, understand, and react successfully to new or trying situations’?

To use the concept ‘intelligence’ when referring to plants is also a contested subject associated more often than not with measuring the capabilities and potential of the human brain. But ‘intelligence’ in Mancuso’s terms in The Revolutionary Genius of Plants is more philosophical, as ‘inherent to life, whether there is a brain or not’.  The intelligence of plants he describes as ‘distributed intelligence’ manifest through their diffuse organs. In the absence of a central organising organ, a brain, he says ‘plants distribute over their entire body the functions that animals concentrate in specific organs. Decentralization is key. We have discovered that plants breathe with their whole body, see with their whole body, feel with their whole body, and evaluate with their whole body’. Mancuso’s two books provide ample evidence of this theory. For example, take the case of the mimetic ability of the Boquila Trifolioataa liana, a woody, grounded-rooted vine that grows in the temperate forests of Chile and Argentina. This plant has the potential to mimic the leaves of the shrub or tree around which it grows, but a single plant is also capable of changing the shape, size and the colour of its leaves according to the species that grow close to it. The capacity to effect a change in its leaves so readily indicates, Mancuso suggests, that plants may have a rudimentary form of vision due to the cells in their epidermis.

Plants are, as Mancuso says, different. His more recent book, The Incredible Journey of Plantsadds to our understanding of the capabilities of plants, but he shifts from the structure of plants to the techniques they utilize to migrate around the world. Plants grow in remote areas of the world; they have been able to live in areas where radio-active material might be present. Mancuso shows us how plants have become great survivors and colonisers of continents and countries and nooks and corners across time.

Jonathon Drori’s Around the World in 80 Treesis more focused on a specific number of trees from amongst the myriad that grow on the planet, chosen he says for their interest and their diversity. He acknowledges however, that they represent only a tiny fraction of countless ways in which trees and human beings interact. His selection of a limited number of trees does not, however, detract from this truly delightful book. Apart from knowledge, the book is of particular interest for all the dimensions of publication: presentation, engaging content, and superb illustrations.For anybody interested in trees and indeed their relatedness to history and human beings, but not necessarily an expert in the field, as is the case with me, this book is highly accessible and cannot but fail to give pleasure to the reader.

When there are at least 60,000 distinct species of trees in the world, our personal ‘likes’ reveal to us our limited understanding and appreciation of them. We might have a ‘favourite’ tree and that ‘like’ is usually consequent our own habitat. As a child growing up in Australia, a very tall gum tree in the field in front of my house was host to kookaburras on route to somewhere or using it for nesting and was as much a part of my environment as was my home. Likewise, weeping willows along the great Murray river on the border between New South Wales and Victoria were ‘favourites’ of mine. In Asia also, I was introduced to a number of new trees such as the palmyra tree, every part of which is useful to humans for one purpose or another.  In England now, the English oak tree, its deep interaction with human beings and its role in history, the sustenance it provides to many life forms and its sheer majesty is my ‘favourite’, although beeches run a close second. I am very partial to the swamp cypress with its ‘knees’ protruding through the water surface where it grows so elegantly on the edges of the stream in one of the local parks.

While my appreciation of trees is confined to the local, Drori’s eighty trees are identified and arranged geographically, heading eastwards from his home in London around the world, and the book may skip to thematic issues on the odd occasion, but none of these structural shifts distracts from the reading of the book: each tree is interesting in itself. He opens his commentary on trees, with the London Plane (Planatus x acerifolia), an excellent example of how an immigrant and one of mixed parentage became a symbol of English power and prestige. Planted during the nineteenth century, it adorned the streets of the capital of a growing empire and its particular structure enabled it to survive the soot from heavy industry where others could not.

Throughout the book, Drori documents an amazing array of diversity of forms of trees, and the unexpected uses to which many have been put in the service of human beings. Millions of us regularly pop an aspirin for any number of reasons without even considering that the basis of this analgesic medicine, salicin, is produced by the willow, one of which is the White Willow.  After we have swallowed our aspirin, many of us might head off to the theatre to listen to the ‘cry’ of the melodious violin, without any consideration at all that apart from the talent of the musician playing the notes written by a creative genius, the purity of the tone given out by the violin is enhanced by the wood from the tree that the it is made: the Norway Spruce (Picea abies).

Norway Spruce is a light wood, but it has exceptional stiffness, and combined with other attributes it is ideal for instrument making. Thus, it is from the Norway Spruce growing in the Italian Alps that Stradivari and Guarneri made the most renowned violins in the seventeenth and eighteenth centuries. In recent times the ideal conditions for the growth of Norway Spruces is Switzerland. Trees are felled during the cold dormant months before the new moon. But the felling of the tress is just the beginning of the process leading towards the production of an instrument. Once felled, the trees are sawn into billets and the wood is slowly seasoned for at least ten years before a tap with the knuckles determines its readiness for the making of a violin. Fifty years of seasoning, however, is said to be the ideal period of time if even better instruments are to be produced.

But while the Norway Spruce has enriched the calibre of creative arts in the form of a musical instrument, the Alder (Alnus glutinous) is largely responsible for the endurance of one of Europe’s most beautiful cities: Venice. Alders love water and thrive along riverbanks and in wet places. As the city expanded into marshy areas, the Venetians realised that the submerged alder was ideal for use as floodgates and to support great buildings. After draining areas, Venetian engineers drove piles into the mud and subsoil and then poured stone and brick around them. Much of Venice was built with alder wood as its foundation.

Usefulness aside, trees are architecturally and sculpturally diverse, coming in many different shapes and sizes. Thus, the tallest tree, the Coastal Redwood (Sequoia sempervirens) found in the United States, grows to 115 metres (380 feet). But how clever is this tree? It grows to the height that can sustain the lifting of water 120 metres, after which the laws of gravity would intervene to prevent water reaching the top of the tree resulting in its dehydration and death.  Equally amazing in size is the Banyan (Ficus benghalensis) found in India. The Coastal Redwood may reach the skies, but the Banyan tree grows outwards and can have an extra-ordinary expansion of four and a half acres of aerial roots that hang from the branches. And then there is the Quaking Aspen (Populus tremuloids) that also grows in the United States.  For Drori, a stand of aspens ‘makes the heart leap’ such is its beauty. Drori further informs us that a single stand of Quaking Aspens in Utah, known as Pando, contains over 45,000 trees, covers more than 100 acres and probably weighs 6,500 tons. The colony maybe up to 80,000 years old and possibly genetically identical from a common root system.

Drori’s tour of trees from around world ends in Canada, appropriately with a sweet story in the form of the Sugar Maple (Acer saccharam). The production of its delicious syrup enjoyed by millions on pancakes and in other desserts is one aspect of this tree: it is equally famous for the splendour and the joy its exquisite show of colour from its leaves brings to us during autumn.

Arguably, in the context of being surrounded by trees and plants we forget to appreciate them, and certainly their beauty over-rides the complexity of these extra-ordinary life forms. Each of these books however, redresses those omissions and explores the life of plants, but from different perspectives. Mancusois primarily concerned with demonstrating plants as intelligent beings, and the different behaviour of plants that has made them masters of survival and expansion, frequently into places where humans might fear to tread. Drori on the other hand, through his selection of eighty trees from across the globe, tells us not only about the uniqueness and beauty of each tree, but how far it has interacted with the life of human beings. The illustrations are a bonus in this extraordinary book, providing an image of the tree and its components, and thus bringing the tree to life in our imagination.

Ironically, while living in a world of ‘social-distancing’ at this moment in time in the United Kingdom, these three books have taken me on a grand tour around the world, visiting plants and trees and learning about how they survive and thrive while bringing joy and delight to the world. Perhaps there is something for us all to learn from the intelligence of plants.