Last Monday, after visiting the 400-year-old black mulberry at Charlton House, I took the bus to Greenwich Park and paid homage to another venerable, albeit younger, black mulberry next to the cricket pitch. Then, passing some extraordinary veteran sweet chestnut trees with trunks over 6 metres around, I walked straight down the hill, through the National Maritime Museums and on to the old Naval College, which is now part of the University of Greenwich campus. I was there two years ago, in August 2014, photographing two splendid, mature black mulberries and a dozen or so young white mulberries donated by the Worshipful Company of Fruiterers to mark the Millennium in 2000.

This relatively recent mulberry heritage in Greenwich is a reminder of the mulberry plantation that grew here in the 17th century. Elizabeth I had a mulberry garden here and after James I gave Greenwich Palace over to his consort, Queen Anne of Denmark, John and Francis Bonoeil were granted the office of Keepers of the Silkworms at Greenwich and Whitehall in 1614.  And, just down the road in Deptford lived diarist and tree expert, John Evelyn, author of Sylva, published in 1664, which became one of the most influential texts on forestry for centuries. Evelyn was also enthusiastic about the English silk project and wrote of his visits to silk farms and mulberry gardens in his diaries.

It was quite a disappointment, then, to find the whole central area of the grounds around the Dreadnought and Stephen Laurence Buildings fenced off for demolition work when I got there. The tall black mulberry near the south-east corner is now inaccessible and hidden from view by construction workers’ huts. And most of the young white mulberries lining the railings along College Way can only be seen from the road. The gates were still open, though, and I was able to go in, in the hope of finding the black mulberry beside the drive along the west side (King William Walk) that was there two years ago. I remembered photographing the dappled shadows it cast on the white 18th century buildings, as well as eating the fruit and avoiding the purple splodges of exploded mulberries on the ground.

But there was no mulberry ­ just a row of Plane trees by the railings. I walked up and down, wondering if my memory had gone completely haywire. Then I saw a sawn-off stump where the tree had been. The circumference was surprisingly slim, given how high I remembered the tree being ­ something like 8-10 metres.  But it was definitely the mulberry. I could see traces of the characteristic light brown bark and then, miraculously, I spotted two tiny mulberry leaves sprouting from the edge of the stump. Wondering why it had been cut down ­ and praying that it wasn’t part of the demolition work – I asked one of the security guards if he knew of a tree being cut down recently. “Oh yes,” he replied. “Just a few weeks ago. It was hit by lightning. It was split right down the middle. They had to cut it down. It was dangerous. Shame ­ a 60-year-old tree.”

The initial sadness at the loss of the tree soon gave way to a feeling of wonder at its resilience. It was not dead. Given care, it could grow back again, just as it had been. And this reminded me of some remarkable facts about many deciduous trees. They, or at least their DNA, is potentially eternal. Deciduous trees, like oak, hornbeam – and mulberry -  do not die of old age. Indeed, this underpins the age-old practice of coppicing and pollarding trees in woodlands to provide an endless supply of firewood as well as timber and poles for tools, fences, gates and so on. These trees usually only die from disease, for example when frost or dehydration has caused the bark to crack, leaving a way in for insects or fungus to attack.

Mulberries are naturally resistant to disease and pests. They are thought to produce chemicals that act as a deterrent to insects ­ which is ironic given the massive cultivation of the white mulberry precisely because it is food for the silkworm, Bombyx mori. But, of course a tree can be blown over by strong wind and, in one sense, cease to exist. One of a tree’s lifelong challenges is precisely to grow a large canopy of leaves while not becoming so top heavy that it is easily toppled in a gale. But even if it is, the tree can send out suckers and continue to grow. Interestingly, one of the features of the mulberry is its tendency to produce large numbers of these suckers. The sprawling mulberries at Charlton, Syon House, Sayes Court and the Queen’s Orchard are all examples of collapsed trees continuing to grow for three or four centuries and showing every sign of being able to continue for another three or four under the right conditions.

Now, the main threat to London’s mulberries is not disease or old age, but the developer, which is why it is so important to identify the City’s heritage trees, to raise their public profile and to campaign to preserve them when they are at risk of being felled through ignorance or a failure to appreciate their value.