Every Wednesday, I hope to find a new ‘weed’ to investigate. My only criterion will be that I will not have deliberately planted the subject of our inquiry. Who knows what we will find…..

Dear Readers, my visit to East Finchley cemetery last week was the gift that just keeps on giving. I felt that this venerable tree deserved more than a few lines in a longer piece, and so this week I want to look at the ginkgo, a popular street and cemetery tree here in North London, and yet one which I have often hurried past. Before anyone gets over-excited, this is quite clearly not a ‘weed’ by any normal definition, but have you ever tried finding a ‘weed’ in mid-November which, after nearly four years of weekly posts, hasn’t been covered? Flexibility will be required from hereon in, I suspect.

Gingko is immediately identifiable from its leaves. No other living tree has fan-shaped foliage, but fossilised ginkgo leaves have been found from 270 million years ago. The tree existed at the same time as mare’s tail, which was a Wednesday Weed a few weeks ago, but, unlike that plant, poor ginkgo really is the last of its kind. There is nothing else alive that is remotely like it.

Once I spotted one ginkgo, I found them everywhere: at the end of Archway Road, in St Pancras and Islington Cemetery, and on Durham Road. But they are, in some ways, problematic. Ginkgo trees have separate sexes ( the technical term is dioecious), but each sex has some disadvantages as a street tree. The female trees produce a fruit which looks a little like an apricot (the name ‘ginkgo’ is said to come from a misspelling of the Japanese name for the plant, which means ‘silver apricot’) but if this falls and starts to rot, it is said to produce a smell that combines the odour of vomit with the stench of rancid butter. The pollen of the male trees, which naturally produce no fruit, is highly allergenic, and so not good for hay fever sufferers. Nonetheless, the tree is beautiful enough for groundskeepers everywhere to keep planting it.

Incidentally, among its many peculiarities is the fact that the male ginkgo produces sperm which is covered in tiny mobile hairs that enable it to move. In this, ginkgo is similar to mosses and algae, but completely different from flowering plants. It has several adaptations to a time before these competitors came along: for example, it grows very quickly to a  height of about 10 meters before extending any side shoots, which was probably because most plants at this time were ferns and horsetails, and so the need was to get as high as possible as quickly as possible, and then to shade out everybody else.

Not only is the ginkgo a very ancient species, but individual trees are both resilient and long-lived. Six ginkgos which were within 2 kms of the epicentre of the Hiroshima atomic bomb blast survived, and are given the honorable name of ‘hibakujumoku’, or ‘survivor trees’.

At the Tsurugaoka Hachimangu Shinto shrine in Japan a giant ginkgo which had stood beside the staircase since the creation of the building in 1063 finally collapsed in 2010. A botanist who examined it declared that the trunk had rotted. It was thought that that was the end, until both the original tree stump and a piece of the tree planted nearby started to produce a fine crop of new leaves.

If you go into any chemist, you are likely to see herbal preparations with pictures of that distinctive fan-shaped leaf on the box. It is often marketed as a way of delaying the effects of old age, perhaps because the tree itself is so sprightly, and we hope to acquire some of its characteristics. It is said to be beneficial for macular degeneration, dementia, forgetfulness generally, ‘post-menopausal cognitive decline’ ( I guess that’s when I start a sentence and have no idea what I meant to say by the time I get to the end), post-stroke recovery, arterial disease and tinnitus. Oh that it did half of what it says on the packet, but sadly scientific trials have all currently drawn a blank. There is also some fear that if you are taking a blood-thinner such as warfarin or coumadin, overdoing it with the gingko will result in rather thinner blood than you were hoping for. On the other hand, Chinese doctors have been using ginkgo since 2800 BC, so I refuse to lose hope. The plant is certainly full of interesting chemicals such as amentoflavone (which can inhibit the uptake of certain medications) and ginkgolic acid, which is highly allergenic, so maybe these can be turned from ‘the dark side’.

You might think that there would be nothing edible to be found on a ginkgo tree, what with all that talk of the smell of the fruit, but the seeds of the ginkgo (once the smelly stuff is removed) are a traditional food in both China and Japan. In particular, they form part of a celebratory dish called ‘Buddha’s Delight’ which is served at Chinese New Year, a time when a vegetarian diet is thought to bring good luck. And very tasty it looks too.

Whilst researching this piece, I came across this painting by the Japanese artist Watanabe Shotei, and promptly fell in love with it. I like the way that the crow is framed, and the way that the autumn-yellow ginkgo leaves are scattering as she flies through them. This is very different from his other, more formal work, and I think that it sums up the mischievousness of the bird as it ploughs through the august foliage. Or maybe it’s just me.

And finally, there is a belief that even in the shedding of its leaves, the ginkgo is not like other trees. Whilst the oak leaves and the maple leaves drop off one at a time, all the leaves from a ginkgo are said to fall in one night. I can’t say I’ve seen much evidence of that happening with the trees that I know, but maybe this is the case in harsher climates. The poet Howard Nemerov had this to say on the subject:

Late in November, on a single night

Not even near to freezing, the ginkgo trees

That stand along the walk drop all their leaves

In one consent, and neither to rain nor to wind

But as though to time alone: the golden and green

Leaves litter the lawn today, that yesterday

Had spread aloft their fluttering fans of light.

What strange communication occurs between these ancient trees, I wonder, and what complex combination of chemical signals would give rise to such a thing? The more I learn about trees, the less I know.