THE tree just leapt out at me, causing me to swerve quite severely. I drive that road daily, and it hadn't been there on Wednesday. But on Thursday it jumped out of the green hedgerow at me.

Thursday was a crystal-clear blue sky day, the sun shining so brilliantly that you felt it would never allow itself to be snuffed out by autumn's damp mists and murks.

The tree in question - an immature sycamore - had earlier in the week blended into the hedgerow. The leaves on the scrubby stuff around it tiring as September turned into October, their crisp edges blunting, their vibrant green fading to drab.

But the sycamore chose Thursday to bound out of the end-of-season dreariness. It leapt out in a riot of colour. Bathed in yellow with the blue sky backdrop, its leaves shone out the richest gold and the most vivid ruby red. A neat coloured carpet formed at its feet to complete the pretty-as-a-picture.

So startling was it on a main road into Darlington that I nearly straddled the white line. I was, quite literally, driven to distraction.

They say this year is going to be the most colourful autumn in living memory. The warm and dry August and early September has increased the sugar concentration in the leaves and so "tree-peepers", as the Americans call them, should have intense colours to see.

A leaf's job is to catch the sunlight. It uses the sun's energy to convert the water rising up its trunk and the carbon dioxide it plucks from the air into a glucose. This sugary stuff is the tree's food.

There are four pigments in a leaf to catch the sunlight: green chlorophyll, yellow xanthopyll, orange carotene and grey phaeophytin. The chlorophyll is where all the food production occurs, so green becomes the dominant colour of the leaf.

But at this time of year, the tree senses the days are getting shorter and the temperature is dropping. It realises winter is coming and soon there won't be enough light or heat to produce food. So it shuts down.

A layer of cells grows over the tubes which pump water into the leaf. The leaf is cruelly cut off; death awaits it.

Because the cholorophyll has been the most active, it is the first to die. But its death gives a rare moment for the other pigments to shine forth. Having spent all summer overwhelmed by green, the carotene and xanthopyll grab this window of opportunity with the most colourful of dressings.

In addition to their oranges and yellows are the rich reds. These are created by the sugar that has become trapped in the leaf when the tubes were sealed. With no way out, and heated by the last warmth of the year, the sugar turns into a beautiful bruise of purpley-reds.

Nature may, if we're lucky, choose to enhance the show. A burst of rain about now will enhance the intensity of the colours; low temperatures (but not below freezing) will encourage the reds. But a frost will destroy them.

So I pulled over and picked a few leaves from the colourful carpet. They are before me now. One honey gold with veins of fiery pink; another sunburst of purple bleeding into yellow.

But already they look jaded and tired. The dew gave them sparkle. The sun gave them shine. They were better off on the roadside where they could jump out on unsuspecting motorists. If leaves could kill...

Published: 01/10/2005