Garden School:

Garden School:
Teaching this week: Rose pruning (as always!) and water management

Saturday, 26 April 2014

Why are flowers pretty?

Molly's Thought of the Day the other day was this:

"What is it that makes flowers look nice? What evolutionary benefit is there of finding flowers attractive?"

The first question is, who is Molly: answer, the grand-daughter of one of my Clients, who handed me a piece of paper with the above question, and asked me what I thought.

It's a very good question - and the answer lies with our habit of fiddling around with the world to make it suit us.

In the past couple of years I've been studying wildflowers, a class of greenery previously labelled by me as "weeds", and I've discovered that while many of them are things of beauty, they are mostly tiny, and they only last five minutes. This has reinforced my admiration for "cultivated" flowers, flowers which we have bred over the centuries, to be bigger, more colourful, more shapely, longer-lasting, more (or less!) scented, and generally to be "nicer" to our eyes.

So the first and easy answer is that flowers are not naturally "pretty" to our eyes, we have bred them to be that way - and the clear evolutionary advantage to the plant in allowing us to manipulate them, is that we then breed more of them. However,  we also interfere with their natural processes when we do so, and many modern flowers are sterile - they don't set viable seed - and many more don't "come true" from seed, which means that the seedlings will not necessarily look as attractive as the parent.

(I could give you a lecture on Mendelian genetics and F1 hybrids at this point, but if  you are that interested, you can look it up for yourself!)

So by interfering with the evolution of flowers, in some cases we have destroyed their ability to recreate themselves accurately. Which is fine until we lose interest in them, in which case they will gradually die out. Not exactly an evolutionary advantage.

The second part of the answer lies in the phrase "to our eyes".

The evolutionary point of flowers, the reason for them to exist, is to attract pollinating insects - yes, it's all about sex, I'm afraid!  This means that the arrangement and colour (and scent) of the petals and sepals are not made for our benefit at all, they are made to attract insects, many of whom don't use the same set of light wavelengths as we do. They literally see things differently, often using bits of the spectrum that we just don't even notice, such as infra red and ultra violet.

For example, we all know what a dandelion looks like, right? Round yellow thing, lots of thin straight petals (technically, they are ray florets but don't let's get distracted), just yellow.

But when seen with a UV light filter, they suddenly have a very clear and obvious centre, which shrieks "land here!" to every bee that sees it.

Don't believe me? Here's a photo - right - of Dandelions by UV light, but please be aware that the "colours" are not really red and white, they are two differing UV radiations that we simply can't see. The photographer chose to show one wavelength as red and the other as white, for convenience (and for beauty) but those are what you might call "false colours".

This illustrates that insects see the flowers in a very different way from the way that we see them.

Many flowers are like this, with a bold "Get It Here" sort of marking in the middle, where the pollen is. Some have guide lines or landing strips instead.

If you are at all interested in this - and who wouldn't be? - there are some very good websites to look at. I found this one, by an unpronounceable Nordic chap, to be colourful and quite informative.

So the other answer is that flowers are only "pretty" by accident, and there is no evolutionary advantage to it.

Actually, a third answer could involve the fact that some wild flowers - or "weeds" - are not particularly pretty at all, and yet are about as abundant as it is possible to be. I am thinking of things like stinging nettles, and ivy: not pretty in any real sense, but they grow anywhere, are found everywhere, and take over if you don't weed them out. They don't seem to feel the lack of being "pretty",  judging by their success, do they?

So, in answer to Molly's question, there are three possible answers from a Botanist's point of view: I imagine that she would get a different answer from someone with a different speciality?

Monday, 21 April 2014

How to: remove ivy from a wall.

One of my favourite jobs, in the sense that I hate, loathe and detest ivy in just about all situations.

So there! Yes, yes, I know that there are times and places where ivy is useful, and I am fully aware of the wildlife value, but any walk around any town or village will reveal acres of the stuff, along with an underplanting of nettles, down every back alleyway, every undeveloped site, every neglected corner... there's really no need to allow ivy and nettles to spoil the look of our precious small domestic gardens, when there is so much of it around. Despite what the trendy TV Gardeners may say!

Anyway, this was a small border that I was refreshing for a Client: they were tired of it, and wanted more colour in winter, and in particular they wanted berries up the wall, instead of the current decorative ivy.
This is what I started with: Persian ivy at each end, a small Eleagnus at each end (in clashing colours), and a mess of Alchemilla mollis in the middle, along with a failed Honeysuckle that had been chopped numerous times, and had sent up weedy little sprouts all through the bed.

Oh, the ivy had been chopped back every few years, when it swallowed up the windows, so although only three foot high, it had a massive root system.

The whole bed is north-facing so it doesn't get much light, it's under wide eaves so it doesn't get much water, and it's out of sight of the house, so it doesn't get much attention.

However, the Client was prepared to put some effort (mine) and money (theirs) into it, so I prepared a planting plan, had it approved, then sent the Client out shopping for new plants, while I got to work.

Firstly I cleared away all the unwanted planting, digging out all the honeysuckle roots in particular. Then I cleared away as much soil as I could from the massive root of the main ivy plant.
Here is the result, with my trowel to give you an idea of the scale.
And this photo shows the extent of the roots.

In cases like this, you need to get out a decent amount of the roots to prevent regrowth, but you don't need to clear all the long roots.

I find it's best to expose the roots like this, by digging with a fork to start with, then on your hands and knees: then cut off all those roots as close as you can to the main root, then pull them out of the soil as much as possible.

If you can't get them free, or if - as in this case - they run under the grass, just chop them off as far out as you reasonably can.

Once I had severed all the roots, I was able to peel off the whole plant from the wall.

Note the interested bas-relief texture of the wall on the reverse of the plant!

With that monstrous thing out of the way, I was able to get at the bed properly, and dig over the whole area.

I saved the best of the Alchemilla, to be replanted later, and some of the Lily of the Valley, but every other scrap had to go.

Once I'd cleared it, I did a raid on the compost bins, added a big load of organic matter, plus a couple of fist-fulls of Bonemeal and some slow release pelleted chicken manure which I found in the shed. It smells revolting, but once you dig it in, it's gone, and it will give this rather tired soil a good boost.

So there we are, all ready for the new plants!

Thursday, 17 April 2014

How to move a Monkey Puzzle tree.

Best done while they are still tiny...  a friend of mine moved last year, and when the tree blokes came to chop down some over-exuberant Leylandii hedges, they pointed out that the small, funny-looking tree right by the back door was actually Araucaria araucana, also known as Monkey Puzzle, or Chilean Pine. And it was going to get very, very big.

She offered it to me, on condition that I came and dug it up myself, which seemed like a reasonable bargain, so I went over there a couple of weekends ago and did the deed.

Here is what we started with: one small Monkey Puzzle, squashed into a tiny border, and right by the back door.

Can you see that the ends of the lower branches are not single at the end, but have branched out?

That is because the previous occupiers have hacked off the ends of the branches in order to get past it. And whenever you cut the tips off the branches, they, well, branch!

 Digging it up was not much of a problem, there were two longish roots that I couldn't quite get out, so they had to be cut off.

The tricky bit was wrapping it up beforehand - in case you didn't know, this tree is just about the prickliest thing known to man, and draws blood at the most casual touch.

In order to avoid unnecessary bloodshed, I gently bent the branches upwards, and tied them with string, then wrapped the whole thing in brown paper (with copious thanks to Paula for the suggestion) and tied it again.

Here we are safely at home, and plunged into a trough of water to have a good drink and recover from the experience.

Please note that the brown paper wrapping is nearly off - it's a real wriggler!

Next day, it was time to get it into a pot, so I pulled the brown paper back into position and potted it up.

Once again, please note that the tree is definitely trying to wriggle out of the wrapping!
 Without the paper, here is the strange contorted branch arrangement, without which I would not have been able to dig it up.

It was bad enough potting it, I had to wear my thick Winter Touch gloves.

And even then, one little branch escaped the string, and stabbed me in the wrist.


With cries of "stand well back!" I released the string, and here it is in all its glory.

It was immediately apparent that as well as being flat on one side - where it backed onto the fence - it is disproportionately wide.

Looking at it from the "right" side, it's clear that those lower, tufty-ended branches are going to have to go, along with three spindly ones that are adding nothing to the overall shape.

"Snip! Snip! Snip!"

Done. Much better.

Ah - Houston, we have a problem!

Bearing in mind that every leaf on every branch is tipped with a rock-hard, razor-sharp spine, this little tree is in the wrong place!

This is the only corner of my front yard that has room for it, and now I can't get to the Fritillary.

Looks like it's going to have to emigrate to the back garden, any day now...