Surrey Homes | SH36 | October 2017 | Kitchen & Bathroom supplement inside

Garden
Fall in Love
Sue Whigham admires autumn displays of glorious colour
Credit: Sue Whigham, FreeImages.com/Anette Kristensen
It’s the first week of September and a glorious morning
for a walk so it’s on with the boots, on with the
dog’s lead and off down the lane. There are plenty of
blackberries in the hedgerows and a pair of buzzards are
mewing overhead. A group of swallows is gathering in my
neighbour’s field and we come upon thirty or so rooks
feasting on the recently harvested fields. Then through the
stile and across the fields to the back of the church, gathering
a few field mushrooms on the way whilst keeping our eyes
peeled for the beginning of any change in leaf colour. Each
year is different depending on conditions as far back as the
spring, but this year, well, the cornus in the hedgerows has
already turned a deep purple which, combined with blackberries,
is pretty stunning. The hornbeams are losing their
leaves faster than they have time to turn which, bearing
in mind how dry it was this summer, is hardly surprising.
Patches of the tall limes we pass have become a glorious
yellow and the ash by the gate is just on the turn.
In the garden two tree species are beginning to put on a
show. On the strength of seeing an avenue of limes, Tilia
cordata ‘Winter Orange’ at RHS Wisley a few years ago,
we planted one here. This is a really lovely selection with
red buds and bright orange winter shoots. It hasn’t flowered
for us yet but we don’t want to be greedy as we now have a
lovely autumn display of buttery yellow leaves and they are
certainly enough to be going on with. The other tree that
really is worth its weight in gold is Crataegus x persimilis
‘Prunifolia’. I’m sure I’ve mentioned it umpteen times but it
is a tree which deserves more than just one passing comment.
What are its attributes? Well, it’s an all rounder really with
showy blossom in the spring, and rather shiny oval leaves
which by now have coloured up in varying shades of red and
orange. These are accompanied by large clusters of red fruits.
Leaves are green because of a pigment known as chlorophyll.
We’ll all remember that from our Biology lessons at school.
And so when a tree is healthy and happy this pigment
dominates any other in the leaf and is absolutely vital to
the tree. The energy stored by the chlorophyll from the sun
is combined with the water taken up by the plant’s roots
and carbon dioxide taken from the air to produce what the
tree needs to survive, i.e. food. So this is why trees are so
vital to us humans. They create oxygen by this process and
reduce the levels of carbon dioxide in the atmosphere which
we create and which is definitely not beneficial to us.
During the summer months, chlorophyll is
constantly breaking down and being replaced by
the tree and during the approach to autumn, and
then into winter, is withdrawn from its leaves.
This is a bit like closing down a valve to reduce the flow
of water in a plumbing system and is so clever. Where
the leaf joins to the tree, at the leafstalk base, is a thin
layer called the ‘abscission layer’, which is the ‘valve’ that
ensures that production of chlorophyll stops and that any
remaining nutrients are drawn into the twigs of the tree.
This is a ‘process of subtraction’ as the tree’s metabolism
slows right down. So as the green pigment reduces, it leaves
behind yellow and orange pigments known as carotenoids
and xanthophylls. Reds are rather different and are caused
by anthocyanins which are pigments produced well after
the growing season ends. All completely fascinating stuff.
Human activity and resulting climate change is starting
to have an effect on autumn colour. For instance the overuse
of fertilisers leaves excess nitrogen in cultivated soils
resulting in nearby trees storing less sugar in their leaves
than they would in a pristine environment thus reducing
the strength of the bright autumn hues in their leaves before
winter sets in. As I mentioned when talking about the
local hornbeams losing their leaves so rapidly and before
they colour up fully, drought, too, affects autumn colour.
Conversely, excessive rainfall and cloud cover affects colour
photosynthesis, essential to produce red anthocyanins
which result in those fantastic autumn displays.
You’ll know that people flock to New England to see
the autumn fall colours. They’re known as ‘leaf peepers’
over there and they descend in great numbers in what is
normally a rather sleepy and rural part of the States.
125 surrey-homes.co.uk