The trees up above us

'Yes, dear reader, this is a nature column today. It does have a sensational development later on, but only of an arboreal nature'

When I was a part-time gardener in Ladbroke Square, in Notting Hill – I am going back to the days before Hugh Grant was born, and people in Notting Hill could still remember the War, and the barrage balloons moored in Ladbroke Square – in the days when I was actually paid to do gardening, I learnt something about trees from the full-time gardener, Mr Pyke.

Mr Pyke had learnt his trade on big estates in Norfolk, so he knew everything about everything. He told me all about how you grafted one tree on to another to get weeping ashes (there are some nice examples in Ladbroke Square). He told me that you should bury as many autumn leaves as possible in order to enrich the ground, but that it was no use burying plane leaves, as they were too glossy to rot quickly, and could be burnt. He taught me all about the ginkgo biloba, which grew there, and the vast Turkish oak tree that grew bearded acorn cups on the main lawn, and many other things that I have since forgotten.

The only thing he didn't know about trees was the problem of Dutch Elm Disease, which struck the square (and the rest of Britain) while I was there, and which led to a lot of nice trees being cut down, and other trees coming into their own. By the time I moved back into the country in the 1980s, it was almost unheard of to see a large elm tree, and quite rare to see a small healthy one. The landscape is now dominated by ashes and oaks and limes, with of course the ubiquitous sycamore, which seems to propagate itself more skilfully and lustily than any other tree.

In springtime, our local meadow is covered with tiny little sycamore shoots, all programmed to grow into mighty sycamore trees if given the chance. They never get the chance, because the cows come along and eat them, but it's noteworthy that no other tree has the same quantity of shoots out there in the field.

On the other side of the field, down by the River Avon, there is the usual straggly line of riverside trees, a lot of them inoffensive alders. (Yes, dear reader, this is a nature column today. It does have a sensational development later on, but only of an arboreal nature.) There are also quite a lot of willow trees, and over the years I have started to notice that willow trees seldom grow alone. Beside the average willow tree, you often get a hawthorn or an elder tree pushing its way in, spoiling the clean lines of the river bank, but it wasn't until I looked closer that I realised that these other trees are, very often, growing on the willow.

The reason for this is that willow branches often crack, and in these cracks there builds up a deposit of earth and muck and rotted leaves and other kinds of humus, which would probably sell at £20 a bag in your garden centre for potting compost. Into this compost fall little seeds, and these little seeds germinate and start growing, completely unaware that they are 10 or more feet off the ground. So it is quite common to see hawthorn bushes growing at eye level, or elder trees, or brambles – though, of course, brambles don't like growing upwards particularly, so if they take root upstairs in a willow they promptly start growing downwards until they hit the ground.

The oddest example of this is downstream from us by about a quarter of a mile, where a sycamore seedling has taken root in the armpit of a willow tree about 20 feet above the ground. Sycamore seedlings seem to have no natural enemies 20 feet up in the air, so it has grown safely and securely, until it is now a full-size tree.

Yes, there is a full-size sycamore tree growing in the air, 20 feet above the ground. Its base is above your head. The roots then come out of the base and go down the willow tree trunk, looking, looking, for some ground to sink into, until eventually, 20 feet below its base, the roots finally hit the river bank and can do what roots are meant to do – that is, go underground and look for water.

Every time I see this tree, I can't help but think of Thomas Pakenham's book, Meetings with Remarkable Trees, and I think to myself: Mr Pakenham, sir, I bet you never looked up into the air and found your eyes meeting a sycamore tree, growing 20 feet above you....