Tree planting has never had a better press. Carbon capture, climate change, rural stewardship, responsible farming: these fine causes have all raised its social profile. As a gardener, I engage with it yearly in February, when trees are still dispatched from specialist nurseries with strong bare roots lifted from open ground. Planting is possible, even enjoyable, in the interludes between days of rain before the trees come into leaf.
This happy work makes me realise how gardeners and public planters have different priorities. Local councils signal eco-virtue by proclaiming the number of trees they will plant in a year, announcing targets that they aim to hit as if with an arrow from the bow of William Tell. Gardeners want one or two fine specimen trees. If they have broad acres, not small urban havens, they may also want an arboretum. Regrettably, cities and local authorities no longer plant arboretums, those havens for ornamental trees collected all over the globe from China to Peru.
Councils and public authorities are arboreal nativists, polemically committed to planting nothing but “native” trees. Gardeners want flowers and beauty and look for them whether or not they originate in Britain. Along roadsides and batches of new housing, public planters cram in saplings of hawthorn and beech, English oak and those excessive beneficiaries of the nativist agenda, silver birch. Thickly planted, about a foot apart, the majority of these saplings are projected to die long before semi-maturity.
In the past, town planners used to plant arboreta of specimen trees from faraway habitats in urban parks and public spaces, ornamenting the landscape and treating the public to beauty and unfamiliarity. An arboretum of recently found trees from China and Chile in modern Hyde Park? Dream on.
In his new book The Tree Hunters, Thomas Pakenham addresses this divergence in the same clear style that made his Meetings With Remarkable Trees a bestseller. He tells many tales of bold collectors before 1920 who went to gather seeds of trees in the wild and bring them back for cultivation in Britain. He ventures beyond the usual stories of the usual heroes. He then puts the “cult of the arboretum” at the centre of what he rightly calls the transformation of our landscape. I had never joined the two so clearly before. He has form here. Twenty years ago, over-ruling his wife Valerie, he began an arboretum of trees grown from seed he had collected in Tibet and China. It has flourished.
What is an arboretum? A collection of non-native trees, I would say, chosen as specimens for diversity, beauty and unusual features. Pakenham is more strict. He defines it as “a documented collection of trees planted for scientific study or enjoyment”. He wants to distinguish arboreta from woodland gardens, a distinction I would draw by excluding ornamental underplanting and flower beds from a true arboretum. If ageing owners lose the documents that listed their planting, does the result cease to be an arboretum in their heirs’ hands? It has become undocumented, but surely retains its claim to the name.
Pakenham’s research into the first arboreta in Britain and Ireland has taught him that their history is “shadowy”. Even among the shadows I am sure that Shakespeare never saw an arboretum in a strict sense of the term. Pakenham traces their beginnings back to the 1660s, to the two Tradescants, father and son, and John Evelyn, no one-sided nativist, and to Henry Compton, Bishop of London, perhaps the last such bishop to be an apostle of rare trees and initiator of a truly useful mission, one to bring seeds in from North America. The word “arboretum” had simply meant a “grove of trees”, but by the 1760s it began to be applied to special collections, spearheaded by those in royal ownership that later became the botanic garden at Kew.
Compton failed to become Archbishop of Canterbury. Pakenham remarks that in his case, and “no doubt that of many others”, a collection of trees was “an antidote for disappointment”. He stops his book long before the 1960s, but arboreta have certainly not ceased. Public planters have abandoned them, except in botanic gardens, but private owners have planted superb examples. They include the great collection of oaks at Chevithorne Barton in Devon, assembled by Michael Heathcoat-Amory, and the tree planting in Jonathan Ruffer’s major restoration of Auckland Castle and Bishops Palace in county Durham. Each ranks as a successful investor, never toppled by the market to leave it in disappointment.
At Thenford in Northamptonshire, Michael Heseltine, the doyen of Tory ex-statesmen, has spent decades laying out a big arboretum in his massively impressive garden. Outsiders might mistake this one, at least, as an antidote to “disappointment”, as Heseltine’s prime ministership remains one of the great might-have-beens of the 1990s, but those present at the launch, aged 91, of his new book From Acorns to Oaks know better. Semi-retirement gave him more leisure: it did not turn him to a new antidote. His impassioned collection of trees began far earlier in his career, when he had started by believing that “a hornbeam was was a dance they did in the navy in Georgian times.”.
His book covers far more than his gardening. It includes his current blueprint to rebuild Britain and his final discoveries about the degree of official untruth and cover-up used against him during the Westland affair of 1985-86, that crucial dispute over the commissioning of military helicopters which led him to resign from Thatcher’s cabinet. His arboretum benefited, but it had begun already.
Nativist tree planters justly denounce the importing of mature trees from foreign sources and the pests and diseases they may bring in by accident. The foreign trees introduced to British arboreta were mostly grown from collected seed and then propagated for sale quite safely in Britain itself. Nativists also protest that non-native trees do not foster bees, insects or biodiversity. These interrelations are all complex and are less studied for foreign trees, so far, than native ones. Meanwhile, ivy and nettles are basic supports for many butterflies and insects, but grow as well among non-native trees as under natives only.
As a gardener, I have just been moving a sorbus. It is not a native rowan or service tree but a pink-berried Sorbus hupehensis from China. Every year its stale-scented flowers are visited by British insects and then its berries are consumed with glee by British birds in autumn. In my tall Italian alder trees I have thrushes nesting and bees too. Beside them I have been planting yet another winter-flowering cherry, the wonderful Prunus subhirtella autumnalis from China. It remains my top tree for prolonged beauty, never more so than in this wet and grey winter when it began to flower in late November and is still at its finest, with more to come. British blue tits do not only feed on British blackthorn, a scruffy native prunus. They also feed on the insects and aphids and peck at the buds on winter-flowering cherries of Asian origin.
As for silver birches, the whitest and loveliest barks and trunks are on Betula jacquemontii, at home in the Himalayas, and on its varieties selected by nurserymen. They are far lovelier than birches native to Britain, those great invaders after the Ice Age. Do not be one-sided. Bring back global arboreta and break down the barriers of prejudice that keep them out of cities’ public spaces.
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