Paperbark Maple (Acer griseum)

Dear Readers, I was so taken with this Paperbark Maple,  spotted in East Finchley earlier this week, that I had to find out a bit more about it. As you can see, it has bark that peels away in tissue-thin layers of of coral and blush pink. The effect was even more impressive when I looked up at the branches. This peeling bark first appears when the tree is 6 or 7 years old, and continues for the rest of the plant’s life.

While the bark reminds me slightly of when I got sunburn as a child, it’s also a quite extraordinary effect. In his book ‘London’s Street Trees’, Paul Wood describes Paperbark Maple as ‘occasionally planted’, but it seems like a good choice to me – the trunk is the one thing that everybody sees, and so you don’t even have to look up to be impressed. It’s also a tree that’s happy on clay soil (which is basically what London sits on).

Paperbark maple is a long way from home, though – a native of China, it’s usually found at altitudes of 1,500 to 2,000 metres. It was introduced to Europe in 1901, and to North America shortly afterwards: apparently only two trees reached the US, and all paperbark maples in the country are descended from this pair of trees. It is a difficult plant to cultivate – a lot of the fruits that develop are seedless ( a phenomenon known as parthenocarpy, another new word!), and  a joint American/Chinese expedition met up in China in 2015 to try to collect seeds to improve the genetic diversity of the plants in cultivation. This is not purely to enhance North American trees, either – the plant is considered endangered by the IUCN, with the populations in China increasingly fragmented and threatened. It’s quite something to find an endangered plant growing in a suburban street.

The bark isn’t the end of the story with Paperbark Maple, however: in autumn, the leaves flush orange/red. The leaflets are arranged in threes, as are the flowers (which turn into the typical maple ‘keys’). In spring, the leaves are dark green above, but decidedly furry underneath.

I wonder if it’s the difficulty in propagation that results in this amazing tree not being planted more often?

Paperbark Maple autumn colour (Photo One)

Why, though, would a tree lose its bark in this way? Many trees do this, the most familiar to us Londoners being the London Plane tree (Platanus x hispanica). In this species, the loss of bark is thought to be a way of getting rid of accumulated toxins from pollution, although in the very hot summer a few years ago I noticed that the plane trees were losing much more bark than usual, possibly from stress. However, it seems unlikely that a tree that evolved in China’s mountains would be doing the same thing.

Another possible explanation is that the exfoliation helps the tree to rid itself of unwanted parasites and fungi. Yet another is that trees at high altitudes actually have their bark damaged by the UV light from intense sunshine, and also that they might suffer frost damage, so getting rid of damaged bark makes sense. It can also deter climbers and epiphytes. So, who knows? One explanation that I have rejected for ‘my’ tree, as I’ve come to think of it, is that the bark cracks and peels as the tree grows, a bit like an insect growing out of its exoskeleton. In that case, why doesn’t it happen to all trees? And why doesn’t it stop when the tree reaches its full height? Let me know what you think, readers. I know that you’ll all have some native trees where the bark peels, but why? I know we won’t get to the bottom of it here, but it’s always good to ponder.

A Paperbark Maple in summer (Photo Two)

And finally, a somewhat tangential poem. It actually made me tear up, this poem: partly because I remember the sheer excitement of a library, and partly because of the destruction of the library system in the UK which means that so many children will never experience that excitement.

Maple Valley Branch Library, 1967
For a fifteen-year-old there was plenty
to do: browse the magazines,
slip into the Adult section to see
what vast tristesse was born of rush-hour traffic,
decolletes, and the plague of too much money.
There was so much to discover-how to
lay out a road, the language of flowers,
and the place of women in the tribe of Moost.
There were equations elegant as a French twist,
fractal geometry’s unwinding maple leaf;
I could follow, step-by-step, the slow disclosure
of a pineapple Jell-O mold-or take
the path of Harold’s purple crayon through
the bedroom window and onto a lavender
spill of stars. Oh, I could walk any aisle
and smell wisdom, put a hand out to touch
the rough curve of bound leather,
the harsh parchment of dreams.
As for the improbable librarian
with her salt and paprika upsweep,
her British accent and sweater clip
(mom of a kid I knew from school)-
I’d go up to her desk and ask for help
on bareback rodeo or binary codes,
phonics, Gestalt theory,
lead poisoning in the Late Roman Empire;
the play of light in Dutch Renaissance painting;
I would claim to be researching
pre-Columbian pottery or Chinese foot-binding,
but all I wanted to know was:
Tell me what you’ve read that keeps
that half smile afloat
above the collar of your impeccable blouse.
So I read Gone with the Wind because
it was big, and haiku because they were small.
I studied history for its rhapsody of dates,
lingered over Cubist art for the way
it showed all sides of a guitar at once.
All the time in the world was there, and sometimes
all the world on a single page.
As much as I could hold
on my plastic cards imprint I took,
greedily: six books, six volumes of bliss,
the stuff we humans are made of:
words and sighs and silence,
ink and whips, Brahma and cosine,
corsets and poetry and blood sugar levels-
I carried it home, five blocks of aluminum siding
and past the old garage where, on its boarded-up doors,
someone had scrawled:
I CAN EAT AN ELEPHANT
IF I TAKE SMALL BITES.
Yes, I said to no one in particular: That’s
what I’m gonna do!

– Rita Dove

Photo Credits

Photo One from https://treeheritage.co.uk/planting-trees-for-autumn-colour/acer-griseum-autumn-colour/

Photo Two By Bruce Marlin – Own work http://www.cirrusimage.com/tree_paperbark_maple.htm, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=2988653