Saturday, 22 February 2014

Barriers in the garden

Reaping the Whirlwind
Parthenocissus enriching wall in Dunham Park, Cheshire
      And so ends a period of non-stop rain and hurricanes. I now know what 'defenceless' means. It means I no longer have de fence. This is thanks to what the far right bury-your-head-in-the-sand philosophers describe as 'perfectly normal cyclical weather patterns, so you can carry on raping the planet, as long as you're making money and buying more material things'. To my mind, the fact that every new weather event seems to be 'the most extreme since records began' curtails this line of thinking with a question mark. But hey, who am I to question these clever people? It's just that a bit of my fence is now in the pond and the rest of it has become excellent firewood.

      It's quite interesting to think about how the fish see this event. Think about it - one minute you're looking up at an admittedly dull sky, the next - it's as black as hell and you're bumping into each other, wondering how you're going to find the next worm. This must be similar to the situation faced by cavemen when an eclipse occurred, although they'd have the additional hazard of being trampled by disorientated dinosaurs trying to find their way home. Anyway, in the case of the fish, God (me) turned up and took the fence away to join the rest of the firewood. In the same way He (not me that time) moved the moon from in front of the sun so that the cavemen could look up wondrously before going away and inventing religion.

      Religion was wonderful, because it provided the answer to everything: if there was a tragedy, for example, God was angry about the way we'd been going about something or other, and was therefore making us pay (for more information, apply to Ukip). And this leads you to think about what southerners had done that was wrong enough to bring the floods down on them. Apart from supporting Chelsea and seeing the north (anywhere beyond Watford Gap) as a wasteland occupied by savages, that is. Maybe there are a lot of bankers living down there?

      Hearing about the floods in the south of England, where the rivers burst their banks and caused toilets to back up reminds me of childhood trips to Blackpool with my mum on a coach ('sharrers' we called them, which was short for 'charabanc'- something I didn't know at the time because we weren't posh).  Swimming in the sea not far from a damn big sewage pipe inevitably led to the odd occasion when you'd reach out to cling on a floating log before realising it wasn't a log. It was then that you concluded there must be some very big people in Blackpool. This was before the days of the M6 motorway and the journey there would take getting on for half a day. Harold McMillan (remember Harry?) opened it in 1958, to huge excitement as the curtains drew back to reveal the brave new era of sweating it out in 10 mile jams while the kids murdered each other in the back seat. We all thought this was great but, as usual, the Southerners had to go one better by creating the biggest carpark in the world and calling it The M25. Maybe that's why they've got floods. It reminds me of the time Crocodile Dundee flourishes a massive hunting knife under a mugger's nose and says 'now this is a knife, son'. That's what southerners say about traffic jams on the M25.

      Coming back to fences, it's worth looking at how wind works: a solid barrier offers a lot more resistance than does one which allows it to filter through (the Beagle would never have reached the Galapagos and we may still have been waiting for the theory of evolution if the sails had been full of holes). This is why professional nurseries use fencing materials which effectively diffuse the wind. If a solid barrier strong enough to withstand powerful gusts is used, the wind simply whips over the top and creates damaging turbulence on the other side. Brick walls have this disadvantage but balance it by absorbing heat from the sun and creating a warm microclimate by then releasing it slowly. Some of the old walled gardens had fireplaces built into thewalls and added to the natural heat of the sun by using a system of warming chimneys meandering through the structure. An example of this can be seen at Tatton Park, in Cheshire.

      A hedge is often resorted to, as it has the advantage of allowing wind to permeate through, while still offering protection to plants on the other side. Even hedges have their down side though, because their roots can often out-compete plants growing at their base. This can be dealt with by regularly adding well rotted compost to the area at the same time as liberally sprinkling blood, fish and bone. However it is an ongoing task and you have to remain aware of the problem. For a more in-depth look at hedges, go to this link.
Boring fence showing hard outlines
      A fence isn't usually a strongly aesthetic feature in the garden but it is often necessary and its harsh outlines can be disguised in various ways. The typical waney lap has a relatively short lifespan (manufacturers suggest ten years if dipped in preservative and fifteen if pressure treated), so to have valuable plants firmly established on the wood is to lose or at least damage them when this support falls apart.
Fence with outlines softened by training Clematis tangutica on plastic netting
      By hanging netting or trellis and training climbers onto this, the plant can be carefully lowered while fence panels are being replaced. In any case, plants which climb by twining stems, tendrils or modified leaf stems (honeysuckle (Lonicera), Wisteria, Clematis, nasturtium (Tropaeolum), passion flower (Passiflora) and various others) would be unable to find purchase on the flat surface of a fence. Other climbers, like ivy (Hedera spp)or Virginia creeper (Parthenocissus quinquefolia), are able to cling onto hard surfaces and would be difficult to disengage from a fence which needs replacing. A close inspection of Virginia creeper discloses little suckers on the ends of tendrils, which enable it to stick. Maybe that's where Spiderman got the idea.

Friday, 14 February 2014

Transpiration and water conservation by plants

Dying to go
A large oak tree can breathe out 150 gallons of water in a day
      Maybe it's only me, but I find it easy to build a seemingly minor situation into a major catastrophe in my own mind:

      We went to a play called 'Pride' the other night. Usually our theatre trips are confined to the cheaper seats entailing the use of binoculars and, on occasion, vertigo tablets. There are numerous actors whose faces are unknown to me. Show me the top of their heads though, and I know them like a family member. In the Royal Shakespeare Theatre, Stratford, I needed Superman x-ray vision to see round a roof support. However, for 'Pride', my wife had got us possibly the best seats in the house - second row from the front and slap bang in the middle.

      The play was a well-acted study of the unbearable stress a judgemental society places on someone who happens to be gay - people marrying members of the opposite sex to prove to themselves and others that they are 'normal' and in the process messing up both their own and their partner's lives. An insecure, angst- ridden gay relationship inevitably ensues and the play is making a powerful point.

      Unfortunately, within ten minutes of the start, I needed to go for a pee. The fact that I was in the middle of the row however meant that whichever way I went I'd be disturbing about twelve people in full view of the rest of the audience. So I gritted my teeth and determined to stick it out until the interval, using the usual stratagems of shaking my legs and breathing deeply. When I say 'usual stratagems', they may not be yours but are most certainly mine, although I don't know whether a scientific basis has been established. Certainly it is widely recognised that not thinking about liquid helps, and the fact that virtually every scene involved someone pouring drinks was tantamount to tap-dancing on my bladder.

      Anyway, the gay relationship on stage was going through the doldrums and one bloke was threatening to leave. I was pinning my hopes on the likelihood that him leaving the stage would coincide with the interval and I would be able to find relief. A couple of times he walked to the door and was about to go, then he'd come back to continue arguing and I got to the stage where my mind was screaming for the bugger to sod off. Then a horrible thought struck me: very occasionally there isn't a break - the play runs straight through to the end. Christ! my bladder would burst. By weighing up the alternatives of the audience being slightly disturbed against that of them getting their feet wet, I came to a momentous decision, got up and excused myself  to each and every person as I tripped over their hand bags and trod on their feet.

      Eventually I reached the end of the row, aware that a highly dramatic point had been reached on stage, with long silences only broken by this manic prancing figure bobbing along in front, crashing through people's personal accoutrements. Half expecting some comment from the stage along the lines of  'was it something I said?' I reached the exit door. Well- lit by the overhead sign, it was covered with a curtain which I wrestled with, trying to pull it in the wrong direction while, ridiculously, feeling that that everyone in the place was watching me: I'd got myself my own little stage and should give a bow before finally exiting. Old time comics; Charlie Chaplin or Laurel and Hardy, would get a half-hour sketch out of this performance.Then I conquered the curtain and was free, rushing up the stairs to the gents and knowing that I hadn't got the nerve to do this process in reverse - I'd wait until the break before I went back in and, if there wasn't one, I'd just lurk somewhere. It crossed my mind that, in case (God forbid!) this scenario was to repeat itself some time in the future, I'd carry a false moustache, and maybe a wig, in order to escape recognition on leaving the gents.

      I was standing at the urinal, enjoying well earned moments of bliss, when the door burst open and a number of blokes rushed in. At first I thought they'd come to get me but quickly realised that it was the break. I'd left about thirty seconds too soon. That man had left the stage at last.

      And, while plants don't actually cross their legs at the theatre, they still lose a hell of a lot of water (around 90% of intake) through their leaves in a process called transpiration. A large oak can transpire 150 gallons of water a day, which is why pools in woodland area are there all winter but, as soon as the trees sprout leaves, many completely dry up. This is the reason  that we put a plastic bag over cuttings: creating a densely humid atmosphere around the leaf slows down transpiration because water molecules find it difficult to bludgeon their way out. In this way water stays in the cutting until such time as it grows roots capable of replacing water loss.
Cactus spines do more than just deter predators
      At one time, houseplants were much happier in the environment of the living room. That was because we all had coal fires and the burning coal needed oxygen to keep it going, so it sucked fresh air in wherever it could: around window frames, under the door and so on. The thing was, that air contained moisture, something lacking in today's radiator- warmed rooms with their inherent dryness. Not many plants thrive in completely dry air, so we can rectify this by standing them on saucers of grit which is kept damp. The grit provides a large surface area for water to evaporate from, rising to provide a moist microclimate around the leaves and slowing transpiration. Take care not to have the plants standing in water though, as this can lead to lack of oxygen in the compost.

      Plants in very dry situations adapt to slow down water loss in a number of different ways:
Heather moors - Ericas  have evolved their own 'plastic bag' for retaining water
      Heath (Erica) has leaves which curl in on themselves so that they look like a horse-shoe in cross-section. The pores (stomata) are on the underside of the leaf, inside the horse-shoe and are surrounded by hairs. The effect of this is to create a moist microclimate which works in the same way as the plastic bag over our cuttings, slowing water loss; some plants, like Brachyglottis greyii, cover the surface of the leaf with silver hairs which not only slow drying wind movement but reflect the sunlight and reduce water loss  due to overheating. A surprising number of common plants use this technique but it often needs close examination for the hairs to become apparent; cacti, renowned for coping with very dry conditions, have spines performing the treble tasks of deterring browsers, trapping moist air near the surface and acting as a point for mist to condense and run down to the roots. Many cacti are ribbed and the ribs disappear when the plant expands with stored water, only to reappear as it is used up; silvery leaved plants, like lavender, reflect the sun's rays in the same way as those with hairs and this characteristic is something to look out for when choosing plants for a dry spot.

      So it can be seen, just from the few examples I've shown, that plants are far better than me at retaining water.

Friday, 7 February 2014

Acer pseudoplatanus (sycamore) & tar spot

Fear of Flying

Bert's Quadrocopter
There's still a child in all of us, regardless of age but some of us have the fact more prominently displayed than others. Take blokes with model trains. Poor kid gets one for Christmas then can never play with it because dad got there first. My mate Ged got a bit more sophisticated and built a model helicopter. I think the kit cost him about £150 a few years ago and that was quite expensive then.

"Radio controlled", he told me "come round when I've done it and you can see the inaugural flight".

About three months later I got a call from Ged informing me that he was ready for the first flight, so we took the impressive looking model into a large field in Derbyshire and prepared for take-off. A small audience of cows stood in a group to one side of us, edging closer in the nosey ways that cows have.

"It takes a bit of expertise", he said, "you've not got just the main rotors to control - the back one has to be going at the right speed to stop the body spinning". He was right about that, as we were to find out. It seems a shame that he couldn't get a bit of practise in before consigning his creation to aviation history.

The machine was placed on the ground and we stood back as Ged started fiddling with the controls. Nothing happened at first and he had to take the front off the control panel and 'adjust the wiring'. Then he tried again, pressing the lever which, I assume, said 'up'. He had done the adjusting with devastating success, because the rotors immediately started turning slowly, then suddenly became a blur, and the thing shot up to a height of about a hundred feet at a speed which would have turned a crew of Apollo astronauts green. The five cows stared upwards in amazement, bringing to mind that story of the penguins watching a plane take off during the Faulklands war, then falling over backwards when it got too high. It stayed there poised for a moment, then the fuselage (if that's the right word) began rotating in sympathy with the rotors. Ged juggled impressively with his control panel (which would also have dazzled the Apollo pilots) and, after some time, it stopped spinning and reverted to hanging in the air with the small end (tail?) upwards. As was his way, Ged then cracked on it was meant to do that.

"It'll do loop the loop according to the blurb", he informed me, and it proceeded to just that. That is, it got the first part of the manoeuever right, swooping downwards, but omitted the other bit where it zooms up and completes the circle upside down. In spite of Ged's frantic control - juggling, it continued heading vertically down towards us at frightening speed. Our eyes must have grown bigger in proportion to its proximity and then, at the last moment, we dived to each side in in a way reminiscent of that scenario in the opening credits of 'Father Ted'. One of the cows uttered a bellow that I took to be a bovine version of 'bloody hell!' and they stampeded into the distance. I've often wondered if the farmer ever worked out why the milk came out curdled that night.

I don't know how many pieces there were in the kit that Ged made the helicopter out of, but I can guarantee there were far more when it concluded its maiden flight. When, from a prone position in a cow pat, he blinked thoughtfully and uttered a philosophical "oh well, back to the drawing board", I vowed that I wasn't watching the next solo flight without the comforting surroundings of an air raid shelter.

And, as if Ged and his helicopter wasn't enough, another mate, Bert, made a quadrocopter (my name for it). This is a circular central piece, like a CD container (in fact I think it was a CD container), with four arms emanating at right angles to each other and supporting rotors at the outermost end. The birth of this was more prolonged than that of the helicopter, taking almost a year to get to the flying stage, during which time one of the rotors amputated the top of one of Bert's index fingers. He had a few successful tests in the garden before lugging it down to a large, cowless, field somewhere on The Wirral. I was fortunate enough not to have been present at this christening. According to his report, it performed beautifully for about ten minutes, hovering perfectly steadily, and dutifully moving above the field under his guidance. Then, at roof height, it began slipping sideways, travelling across the field unresponsive to the controls before disappearing over the fence of a nearby house.
Test flight
He waited for a crash indicating a broken window, in which case his sixty five year old legs would have propelled him in the opposite direction at a speed you'd hardly expect. However, there was a prolonged silence, so he crept up to the fence and peeped over. The quadrocopter was still in the air, dangling on a washing line. One rotor was entwined in a bra:

"a 38 incher", he informed me (where the hell did he get that expertise) "you could have made a lovely double hanging basket with it".

Making sure there was no one looking, he sneaked over the fence, untangled the machine then legged it, having no wish to meet the owner of the bra. Not under those circumstances anyway.

That's what I mean about the child in all of us, though I suspect women would say it only applies to blokes.
Sycamore 'helicopters' made of willow stems
The tree gardeners love to hate is the sycamore, whose seeds look like helicopters as they make their way to a potential spot for germinating. On a windy day they can fly as far as 350ft from the parent, making this a brilliant seed dispersal method - a point well appreciated when they start popping up in your garden and you haven't got a tree. Their strap - like leaves quickly become strongly rooted saplings and early removal is essential if you want to avoid a hernia. They can, of course, go much further if ingested by an animal, then excreted.
The real thing
Funnily enough, it's a close cousin of the decorative Acer which is at the other end of the appreciation scale. It's Latin name Acer pseudoplatanus  (pseudo -false and platanus -plane) indicates a close resemblance of the leaves and bark to the plane tree. Introduced in the middle ages, it has, until recently, been seen as a second-rate immigrant which supports little wildlife. However, it's now recognised that the fallen leaves have the effect of causing the increase of earthworm populations and wildflowers, like woodruff and wood anemone, thrive in the loam created. The fact that the tree is a magnet to aphids is now seen as a positive in so far as it is important for providing the food for insect - eating birds like house martins.
Tar spot on sycamore leaf
In late summer the leaves often become dotted with black patches. These are caused by a fungus (Rhytisma acerinum), which, though unsightly, doesn't seem to harm the tree. Nail galls, those tiny growths which erupt from the surface of the leaf like miniature fingers, are caused by eriophyd mites feeding. They can attack a single plant cell and this causes the surrounding cells to enlarge and multiply, ultimately forming the gall. In spite of these apparently disfiguring features of the foliage, the wood is much valued for its properties of hardness and attractive whiteness. It's a favourite for use as tables, being so close-grained and easy to clean.

Although we think of sycamore as a dark tree, in spring the dangling yellow flowers can compete with many ornamental trees. Its seed aerobatics are an attraction to children and, who knows, may have initiated the idea for the helicopters which led ultimately to the debacle with Ged's model. So maybe the tree isn't quite the villain we thought it was.