The Plane Forest: Does the City have the Right Trees?

24 June 2013   The Plane Forest: Does the City have the right trees?   Hugh Johnson OBE   You are hovering over a city, and it is not this one. This is Central Park, New York, and it is very clear what is city and what is park, is it not? I have always thought that that view was something I would love to get myself, but I saw it and I thought it was wonderful.   I want you to imagine that you are now hovering over London. You are a flying or perhaps a parachuting botanist, and you land somewhere in London and you look around and you see a lot of trees, compared with most cities, but an awful lot of them seem to be the same tree, and you think it is funny – I have landed in a forest. It happens to be a forest of plane trees. There are clearings in it and there are plenty of buildings in it, but the plane seems to be the dominant tree, and you look around and there are some wonderful specimens, absolutely magnificent trees! Then you think again and you say, well, how can this be because there are no young ones, there are no saplings – they do not have babies, so how can there be a forest without babies?     This brings us straight to the fact that our dominant tree, our most magnificent tree, is a sterile tree - it does not have babies. Now, why not? The answer is: because it is a hybrid, and it is a hybrid between two species of trees which could never have met in nature because one lives in America and the other lives in the East. They are the Oriental plane, known in India I think as the chinar tree, a tree that can grow absolutely vast and will dominate a settlement around which the old men collect in the evening, in the shade, to sort things out; and the American Buttonwood or Sycamore, which is not nearly so impressive.     The two met sometime early in the seventeenth century and married and produced a seedling which we know as the London plane. We do not know when or where it happened. The suspicion is that it happened in Spain, and there is a reason for that, and so one of its several botanical names is Platanus Hybrid Hispanica. Its more current name really is Platanus acerifolia, “acerifolia” meaning “with leaves like an acer or a maple” and that is pretty clear – it obviously does, it has leaves like a very big maple, fingery leaves. It was introduced to this country sometime in the seventeenth century, and it did magnificently well, although this is a coolish climate for it. In fact, the suspicion that it was bred in Spain is because it is slightly fertile, but only slightly. In London, those seeds that fly around in the air from plane trees will not germinate. You will not be able to have new seedlings of London planes. But it does reproduce very, very well and very easily from cuttings, and produces some absolutely magnificent trees.   The oldest one in England, as far as anyone knows, is one that is in Ely. It is just a huge tree! It was planted by the Bishop of Ely in his garden in about 1685 and is about 40 feet round, the trunk, so it is a jolly big tree. They just seem to go on and on and on. They grow quite quickly.     They do not blow down. In fact, none had ever been known to blow down before the great gale of 1987, when a few did, and a few broke, but otherwise, this great tower of a thing will just wave around in the wind and drop a few branches and be absolutely fine.   The tallest one, for those of you who like figures, in this country, is at Bryanston in Dorset, and it is a splendid 160 feet high and has not stopped growing – it is absolutely magnificent!   See if anyone recognises this. It is in the Inner Temple, and the Temple is in the City, just, being this side of Temple Bar, and that is a plane tree that was planted in the late-seventeenth, early-eighteenth century. That is King’s Bench Walk, and you see how the trunk goes right above those 60-foot wonderful buildings, and all the crown is right up there in the sky. I can hardly imagine a more magnificent city tree than that.   It has other qualities too, which I may be able to illustrate…   I have photographed quite a lot of lovely trees and I would love you to share them with me, but this is one in St James’s Park – it is really the Royal Parks in the centre of London which are the high point of plane culture. The Green Park is marvellous, and nearly all the trees there are planes. St James’s Park has a bigger variety of trees.     This one is in St James’s Park, and it has got a label… Now, does anyone spot any errors on that official label?   Platenus x hispanica, London Plane, c.1830 – that is quite likely. South East Asia is pure rubbish!     If I could show you one or two other aspects of the plane tree…but you know them so well…  The question is: do you really appreciate their beauty?   Here they are in the Mall, where they do not grow fast, because this avenue was planted in 1906, and it has not exactly shot up, has it? They look like young trees. Heaven knows what sort of rubbish there is for them to grow in! It certainly cannot be proper soil.   This is the forest I was talking about. This is the almost pure plane forest that cannot happen naturally, and wherever you look, they are beautiful. There is that moment, which was rather late this year, when they come into leaf, and there is a haze, a most extraordinary olive colour, as the leaves come out, and they have turned pretty much green by now.     They are an ideal city tree and they certainly know this on the Continent, where they are planted in squares, in large numbers.     They come into leave late. They provide shade when the shade is needed, when the sun gets hot, and then the leaves fall quite late as well. The snag with the leaf fall of planes is that the leaves do not rot. They are big, flat, slippery, dry things and they need clearing up. They rattle around in the wind, but it is a job clearing them up. So, it is not an ideal back garden tree by any means, but its other virtues get over that.     It also is capable of growing in absolute rubbish, though perhaps not very fast, or in practically nothing at all. This one is growing on the edge of a path, where you can see it appears to have no roots at all on this side. They are really tough old things. That is in the Green Park actually, that one, or just on the edge of it.   So, I have had great fun photographing plane trees. I will not impose many more photographs on you. They do represent a huge proportion of the trees of our city.     The other fact that I have fished out is the fact that in Berkeley Square, which may have the oldest plane trees in London – nobody quite knows which of the Central London squares got its plane trees first, but this seems to be about the turn of the seventeenth/eighteenth centuries. The tree on the southwest corner, which is not a particular beauty – it is rather divided in two – its value has been calculated at £750,000. So, if somebody were rash enough to damage it, they would get a very, very big bill.   The idea of valuing trees arose, I suppose, in the ‘70s. At that time, I was on the Tree Council, and we were wondering what we could usefully do about trees in cities, or trees anywhere really, because people tend not to respect something that does not have a price or a value attached, as we all know. We worked out a formula by which: the species of the tree – was it appropriate to where it was; the visibility of the tree; the health of the tree; the commonness or otherwise of the tree – all these things were factored in, and then we took a random value and applied it, and then you could multiply it as you liked, but – I mean with inflation and so forth. But, I think it was last year, that tree in Berkeley Square was worth three-quarters of a million pounds.   The City, where we are now, has got 2,413 trees. I did not count them, but I suppose somebody did or why would I have that figure?! It is not a lot, the Square Mile. It is an under-treed area. Of these, one in seven is a plane tree. I am quoting figures, not my research, and that really surprises me. I would have thought it was a higher proportion than that.     And you have the difficult question, when you have anything like a monoculture – that is nothing like a monoculture, but when you do have a monoculture, you are of course laying yourself wide open to problems: pests, diseases and so forth.     We hear a lot about tree diseases in the press these days, notably the ash dieback, which is a very nasty threat indeed. Is the Government doing enough about it? Well, it is not actually, by any means, because it is not encouraging individuals who have the means to, for example, spray ash woods with fungicides, it is not encouraging or even allowing them to do that. It is saying “You hang on, you hang on!” DEFRA says we will find a problem to this. We may have to create a new kind of ash tree, mind you, they say, which would take a hundred or two years, but we have got it in hand. I am afraid this is not satisfactory. People who possess ash trees, or love ash trees, or know much about ash trees, want to get going and do something – I mean, that is only natural.   What would one possibly do? It is a fungus disease. One would spray it with fungicide. But are there any fungicides specifically tested for spraying on ash trees? There are not, and you know what regulations do: if they have not been specifically tested for that purpose, you are not allowed to do it. So, there is no experiment going on, and for all we know, the ash trees will all die before we are allowed to do anything about it. Not very satisfactory!   To go back to the plane tree, it is actually generally a very healthy tough tree. As you can see, and we have seen, it thrives in most places. It likes a warmer climate than ours, but it is very happy in the south of this country – not quite so impressive further north, and they are not nearly so common.     But it has, in warmer climates, as in the North of Italy, where there are a lot, and in the South of France, where there are a lot, it has a very nasty bark canker, which is killing it off in large numbers. Geneva is about as far north as it has really been spotted in large numbers, and they have been having to fell the wonderful avenues of plane trees along the Canal du Midi and other canals in France and main roads, and it is a horrific sight and makes one very, very angry, but they become very dangerous. They die rather in the same way as the elm died, and I am sure most people here will remember what a catastrophe the Dutch Elm Disease was in the ‘70s and ‘80s. I mean, people thought we cannot lose that population of some of our most splendid and biggest trees, but we did! I do not want to be scary, so we should actually have a wider variety of trees, and yet, you do not want too wide a variety because it gives you a sense of calm and confidence and “This is the proper tree for this place – thank goodness there lots of it.” We do not want our parks to look like an arboretum, where every tree is different. That would be absurd, and they would lose their dignity and their presence.   The Mayor of London, good old Boris, has overseen the producing of a document on what trees should be encouraged in London in general and what should not, and I was very happy to see that “the Mayor”, in quotes, says, “We should especially encourage large canopy trees.” We do not want a town full of flowering cherries and little pop-up trees – we want trees to be permanent.  We want the big-top, climax of the forest trees, because they are what a city really needs, for shade, as well as everything else.     It is not purely an aesthetic matter though because they have also done a cost-benefit analysis on how much it costs to keep trees in good health and good order – how much does it cost the city and the public purse to do it. Well, they have worked out that it costs very much less to keep big trees for a long time than it does small trees for inevitably a shorter time because, on the whole, small trees do not live as long.   We have got some figures that indicate that small trees over a period of, I suppose it is 100 years, they cost £14 – I do not think that sounds right. Their benefits are worth £23, so you get a net gain of £9; whereas a big tree, the cost would be £18, the benefits £55, and somebody can work out the difference! It is clearly of much, much bigger benefit.   So, what are the potential large canopy trees that we might be planting? I want to just run through them and give you some of the pros and cons for the other ones. The list officially drawn up runs in alphabetical order like this: alder, ash, beech, elm, horse-chestnut, lime, oak, plane and walnut.  I am not quite sure why it stops there because one can think of other trees that could be absolutely excellent, but let us just take those one by one.   Now, my intention was to literally take them one by one, but I do not think I am going to quite manage that.   What do you think that is? There is a very proper oak. In fact, that is the oak equivalent of those wonderful planes that I was showing you. Would it not be wonderful if oaks were a good tree to grow around here?   London has got very few oaks, and it is rather mysterious. There is one down by London Wall I think, and there are certainly a few in the parks, but oaks are not London trees. There is a famous one in Marylebone I think but so they have been tried and tested.     It is very possible that when the parks were established, they found that oaks just did not do because London was so filthy. One of the great virtues of the plane that I have not mentioned is that it survives pollution as well as any tree does. Its leaves are shiny. The rain washes them. Its bark, eventually, as you know, very picturesquely comes off, thus cleaning itself. So, the plane has all those advantages as a city tree and it is quite possible that the oak just did not make it and so many failed that they did not get going.   The other tree that very much did work was the elm, because if you can remember what, for example, Hyde Park looked like 25 years ago, the elms were as big and as fine as the planes. Places by the Albert Memorial, where the Great Exhibition was, there were avenues of absolutely magnificent elms, now, sadly, long gone. The elm has great virtues. I am not showing you a picture of an elm because there are not any, or very, very few. It had this lovely virtue of turning colour very, very late and keeping its golden leaves, even up to Christmas. You would look up into this massive crown of the tree and it would be a golden dome when everything else was bare. Then, very early in the season, it comes, it fruits, and you think why is that – first, obviously, it flowers first, and you look up and you say, well, that tree has gone all purple, miles up there in the sky, and that is the tiny little flowers, and then, after that, as early as March, it has got a primitive greenness. The crown has gone a lovely light green. What is that? That is the fruit. So, it is a performing tree too, but one must not be too nostalgic because we have lost them.   Will we ever get them back? The answer is that the great elms that we had before, the field elm, above all, a very characteristic crown, no, probably not. There have been many moves to breed a disease-free elm, as they would like to do with the ash, and there are some disease-free elms, touch wood, no pun intended, that are apparently succeeding. Paris has latched onto an elm, which is actually called Lutece, after the Latin name for Paris, and they are planting a lot this, and I am sure it is being tried out in London somewhere and, in due course, we may have this elm and it will behave like an elm but will not really look like our elms used to look.   I could not make an alder look very beautiful. They are very handsome and workman-like trees, but to find beauty in an alder, you have to look at it really in winter actually. An alder is most interesting and beautiful in winter because it has considerable catkins, which are rather purple, and it is also covered with cones, which rather suggest it is a conifer, which it most certainly is not, and they are very good waterside trees and they have been planted in some numbers in London streets.     Camden Council really got going on the Italian alder. They grow very well, and they are very straight, and they look rather like a very upright pear tree, with rather shiny leaves, but I do not think anyone gets very excited by them, so we might skip over the alder and come to the ash.   The ash has these great qualities, which I had better not enlarge too much, of a very fresh pale greenness in the early summer, and then, as the leaves harden and mature, they flash and they glint, and so it is a bright looking tree, and contrasts wonderfully with the oaks and the others.     Why are there not more beeches in London? I think probably for the same reason as the shortage of oaks. The beech also is a tree that tends to destroy everything that tries to grow under it.  Beech woods are the darkest woods down below. They encourage bluebells because bluebells need that season just before the trees fill out, come into leaf, and then they do not need the light anymore when they have flowered, and the bluebells cut off the competition – they will not let grass grow, and grass would be a big competitor. So, ecologically, beeches go with certain ground flora, but not great in the city.   So, we could experiment with ashes, but they are certainly not going to be any substitute for the plane.   Next comes the elm, and we have talked a bit about the elm, and we can regret it…   Then comes the horse-chestnut, going down the alphabet. Well, they are wonderful and everybody loves them, and they love the flowers and they love the conkers. This is a real performer tree. It is always doing something – it has got another trick up its sleeve. It has got such magnificent great fingery leaves and they are impressive in their own right. It comes into leaf very early in the year. It is one of the first things to go green, and then you have got the candles to look forward to and so on and so on.   But, it has recently had its own problems, and you have seen how they go brown now in the summer – not an attractive colour at all. It tends to start with the bottom branches, and then you see them getting a premature autumn moving slowly up the tree, not often reaching the top, and that is because a horrible little moth is mining the leaves, the chestnut leaf miner moth. It is quite interesting actually, later in the summer, when you see the lower leaves going like that, pick a leaf, and you will see it has got brown splodges all over it. If, carefully, with your fingernail, you pick apart these splodges, you will find they are little blisters, and inside each blister, there is one of these little moths, and then they spend the winter in the ground, so the falling leaves make a nice place for them, and then up they go, which is why the problem starts in the bottom branches of the tree and climbs higher and higher during the summer.   There may be some cure for that. Nobody is going to start spraying all the horse-chestnuts in the world to try and get rid of it. It is very possible that there will be a predator that finds that a good meal, and in fact, there are experiments going on with predators from I think it is the Near-East somewhere that might be a cure for that.   There is another problem, sadly, with the horse-chestnut, that it does get a bark canker, a bleeding canker, that could kill the trees. Now, I have some responsibility for avenues of trees and things in Cambridge, and we had the chief pathologist from the Forestry Commission came along to discuss whether we should be panicking about the magnificent horse-chestnuts in Cambridge. She said, no, we are all bothered by the disfiguring action of the moth, but the canker will occur in some trees, can pass from one tree to tree, you know it is there, because you see the sap bleeding dark brown from somewhere on the trunk or somewhere on the upper branches, and that is a worry, but it is certainly not a motive to either cut down a tree, if it happens, or not to plant others. There is a risk factor in most of these things, but, personally, I think the horse-chestnut goes on being well worth planting, but you have got to watch it and hope that some cures arise.   Now, the lime tree is a huge success in London. Not everybody likes lime trees because they are attacked by an aphid that makes them drop sticky mess, and they are not very popular in car parks for that reason, beautiful as they are. Wonderful in parks, and, like the plane, capable of living to an immense age – you do not see limes dying of old age. They go on and on and on, and there are various varieties, or species, I would say, species and varieties, that have slightly different characteristics, while still being pucker limes and doing all the things that limes should do.   The commonest lime in this country is actually, like the plane, a hybrid. It is called Tilia Hybrid Europea, and it is supposed to be a cross between a large-leafed lime and our native small-leaved lime, and it is a terrific goer. It also propagates wonderfully easily – you just stick a twig in the ground and away it goes, almost like a willow.     This was, I think the reason why, when the aristocracy started building their palaces in the seventeenth century and the idea of a great ornamental park caught on – there had not been such things before really – they turned to, guess who? The Dutch, because the Dutch are the world’s nurserymen, and they will churn out plants quicker than anyone else, and Holland shipped over millions of little rooted cuttings of this very splendid tree, which were cheap to buy, and there are places like, for example, Castle Howard in Yorkshire, Clumber Park in Nottingham, and plenty nearer here, where the avenues of limes are the whole feature. They are absolutely splendid!   They will grow as tall as any tree in this country. Some of the tallest broadleaf trees in England are limes. The only thing is that they sprout and you get these… This is the hybrid lime. You all know those great tufts of very energetic sprouts that come up from the bottom or anywhere else on the trunk of the tree, and rather spoil its appearance – I mean, really spoil its appearance!  You do not get a lovely great clean elegant trunk, normally. So, by the time that people had discovered that this was a bit of a drawback, they had planted their great avenues and they were not about to unplant them, so the other kinds of lime tree did not really get a look-in.   They are also very good for feeding cattle. That is an important aspect of the choice of trees in the past. It was a very important thing, for a farmer or anyone else, that your tree was appreciated by the beasts of the field, and they were, and elm, munch-munch, everybody loved to eat an elm. I mean, a hungry cow will eat, or indeed deer, will eat any green leaf, practically, but they certainly loved lime, and that was another good reason to grow it.   The last in this list, alphabetically, is the walnut. Now, the walnut can be an absolutely wonderful tree and can grow immense in size. It can be trained to have a lovely straight trunk. The trunk eventually goes a very elegant pale grey colour, and it is a performer as well. The trouble is its performance is not entirely popular to its neighbours. The walnut has nuts, and you do not often get to eat those nuts on an English walnut because they do not ripen very well, but the people who do get to eat them are the squirrels, and so, all through the nutty season, you get a hail of half-eaten, chewed walnuts coming down, and you get an enormous squirrel population.   There are other things that squirrels do that are not very good for the neighbours, like they eat little birds in their nests, they eat birds’ eggs, they are generally very greedy. That is another subject: must we tolerate the grey squirrel forever because it destroys the red squirrel? There are no red squirrels left in areas where the grey is abundant. There are only a few pockets of that beautiful little red squirrel left. In Northumberland, there are some; in parts of Scotland, there are some; on Anglesey, I believe, there are some, where the grey squirrel has not quite got across the Menai Strait, and on the Isle of Wight, there are some, but they will never be able to come back to the places where they have been eliminated if there is a population of grey squirrels.   Now, that is the A-W of the large canopy tree species recommended for London, or any other great city, to which I would like to add – and I am not sure why they are not present, except for lack of opportunities to try them I suppose – and one is that wonderful thing, the tulip tree.   The tulip tree, Liriodendron tulipifera, is as fine as any tree in terms of its trunk, canopy, beautiful leaves, rather like a big maple leaf with a notch cut off the end. Its tulips are not quite the headline feature that they sound like. I mean, people can say, “Tulip tree – where are the tulips?” They are quite modestly coloured, green and orange, about this time of year, and well worth examining, but they are not going to make a spectacle of a tulip tree. But the virtues of the tulip tree are many. It grows to a very suitable, tall, handsome, permanent shape, which is just what we want in city trees. It does not seem to have diseases. It turns the most lovely buttery colour in autumn and that is about it really! I mean, we should have lots more tulip trees.   I did do some consultation when I was planning on planting tulip trees somewhere, in a public place, and they said, “It has been known to drop branches.” Well, yes, surely! It might have been known to drop branches but the elm had that reputation, seriously it had – in fact, there is an old rhyme that said, “Elm hateth man and waiteth!”   The other tree that does get planted, to the general satisfaction, and should be planted much more, is the Norway maple. I would not say the sycamore, which is its near relation and superficially similar, because sycamores plant themselves anywhere, as anybody with a  garden in London knows very well, that those little seedlings in their hundreds come up anywhere near a big sycamore. A sycamore can be absolutely magnificent. Funnily enough, we have one in our London garden, and it is not what I would have chosen at all, but it is about a hundred years old and it is almost as fine in its splendid great trunk as a plane tree could be, and rather similar flaking, patchy bark. It has the lime tree’s disadvantage of having a plague of aphids when the leaves are soft and fresh and young in spring. They are a feast for whitefly, and then you get the sticky problem, so everything underneath is sticky. The sycamore is far too prolific with its children. Its leaves are a bit heavy and rattly, like the plane tree. Otherwise, what can one say?  I mean, it is a possibility, and in big, open spaces, it is not such a bad idea, where the grass is mown regularly, as in Hyde Park for example – there are some, but not awful lot.   The Norway maple, on the other hand, its near relation, grows to full big tree size relatively rapidly. Its leaves are more delicate – they are thinner in texture than the sycamore’s leaves, and they are a very similar shape. It flowers marvellously! The sycamore flowers rather greenly in spring, as you know, but the Norway maple flowers in a brilliant yellow-green, which is a real eye-catcher, and then, unlike the sycamore, it turns beautifully yellow in autumn, and its leaves being thinner, do not clutter the place up so much and blow around and rattle in the wind. So, the Norway maple has almost everything to be said for it.     It has got varieties that are more popular really than the tree itself.   The Norway maple has a popular cultivar whose leaves are red. Now, some people think that if a tree has a red variety, it must be better than the green variety, and a copper beech must be worth more than a green beech. Why precisely that is, I am not sure. It draws attention to itself, that is for sure, and when it comes out into leaf in the spring, it is a very pretty, coppery-pinky colour for a while, but then watch it into the summer and it turns the most dreary, funereal black-crimson, nearer black colour, and that is the way it stays, and I do not see any advantage in that. It just looks like a great big hole in the air actually – it is a black-hole visually. There are other trees that do that, red trees. There is a popular Purple Plum, not on our list of seriously big trees, which people say is very pretty, it has got red leaves, it flowers pink in the spring, and then what does it do? It turns black and that is what you have got for the rest of time.   I think the other variety that happens in trees of course is some are golden, and one of the most fashionable trees of today, is the golden form of the acacia. I have not mentioned acacias because, although they do fine in cities, they are quite short-lived, most of them, they break up the pavement, and most good things have a disadvantage! This is also true of cherries, as gardeners know. Cherries have roots very near the surface. They are all the rage in Kensington.  The Royal Borough of Kensington & Chelsea is cherry-mad and plants them as the main street trees, and then it finds that the paving stones are heaving up and they have to take the paving stones away and then, on the surface of the pavement, there is a great wriggle of roots, which you can trip over – not a top idea. So the acacia has that among its disadvantages.   Its golden form, on the other hand, which is called frisia. This is this tree in spring. This is Prunus blireiana, the purple-leaf plum, and you may say “What could be better than that?” This is also in the city. This is in the Inner Temple again.    Incidentally, there is another candidate tree, which I have not mentioned because it is not in the large canopy category, and that is the birch. People love birches! They have got lovely white trunks and so on. But a birch belongs in woodland, or at the edge of woodland. Try making an avenue of birches, and they do not do the first thing that avenues should do, which is stand up straight. Every birch takes its own little view of the vertical, and so you do not really get a proper avenue – you get a funny-looking arrangement! They do not have the solidity, the dignity, that a city tree should have.   So, would that not have been altogether for those glorious Georgian buildings if somebody had sensibly planted – I am not saying they have to be plane trees, but a row of one well-chosen, solid, straight, long-lived, big-canopied tree?   I have got Robinia frisia here and this is also – you see, the Temple is the nearest good hunting ground to the city for beautiful trees, and roses, and marvellous gardens in there. This is not a great photograph of Robinia frisia, the golden acacia. That is very tall. I was on an elevated vantage point, so it does not look very tall, but that tree is certainly 60 feet high. That is Middle Temple Hall, that building on the right, and that is a lawyer studying his brief!   I think that the only disadvantage with this acacia, to my mind, it can look like a patch of sunlight on a gloomy day, but it is fragile. They do break, not good in a high wind, and then you get these broken branches sort of hanging about in the top of the tree and you have to climb to get them out, which is not very easy.   Ian Ritchie, who recruited me for this very pleasant task, said, “You have got to mention mulberries!” because there are all sorts of legends about mulberries in the City. The Drapers have a historic mulberry. This one is, again, in the Temple, in the Middle Temple. It seems to be the remains of a very, very huge old tree. There is one on one side of this fountain and then there is another on the other side. They are broken fragments really, and this is what happens with mulberries.     Every respectable mulberry is supposed to have been planted by or in the time of King James I, and the reason for this is that King James I was very anti-smoking. You may remember what he said about “Tobacco is a filthy weed and should be discouraged.” Unfortunately, it was the big industry in his new colonies in America, in Virginia. All the farmers planted tobacco, and he thought we must stamp out this noxious weed and give them an alternative way of making a living. Why do they not make silk? I will send them over a lot of mulberry trees, which he did, and the only snag was that he was misinformed because the silkworm does not live on your standard mulberry tree. It lives on the white mulberry tree, Morus alba. Morus nigra is the mulberry that has the staining fruit. Morus alba does not, but it does feed silkworms. So, King James’ attempts at founding a silk industry really came to nothing. We do have a few remnants and that is one, and the leaves are lovely and the fruit is lovely, but they never really, as it were, got off the ground.  But they do look old and the reason for this is that they root very easily from cuttings. You can cut quite a decent sized big twig or a small branch off a mulberry, stuff it in the ground, and you have got, quite soon, a tree that will not look as though King James planted it, but will look as though it has been there for quite a long time. Then, in due course, they break up. They are not solid, long-lived trees, and you get the broken remains of a mulberry. It is very easy to imagine that it is centuries old.   The Metasequoia glyptostroboides. This is one of the latest introductions into cultivation from the tree world. It is a distant relation to the Redwood. It was discovered in China during the Second World War. It was introduced to this country in 1947 or ’48. It is a deciduous conifer, in that respect, like a larch. It grows very fast. It is reputed to like living on the side of a pond and like lots of water, but it grows just as well elsewhere, as in, guess what, Inner Temple Garden! There is one there! It is lurking behind that splendid fence but it must be young – there are not many old ones. It is 60 or 70 feet high and it is just ideal in a situation like that. It is not, in my view, so ideal along the Cromwell Road extension, where Hammersmith Borough, perhaps them or perhaps the roads authorities, have planted them on the way down to the Fuller’s brewery and the roundabout on the way to Heathrow. As a street tree, it is just like a lamppost with leaves really. It does not do that wonderful thing of producing a canopy that gives you shade, that gives you the feeling that the country is not all that far away. It is just a rather mechanical-looking thing, and it will grow absolutely huge, and if it goes anything like its cousin, the Redwood, wait until it is 250 feet high!   So, those are some of the possibilities and a little glimpse of the situation as regards to trees.  Addressing the title of my lecture, which was “The Plane Forest: Does the City have the Right Trees?”  I think a large part of the answer to the question is “yes”.     © Hugh Johnson OBE 2013