Friday, 10 January 2014

Urban Lichen, or maybe just "The City of Gum"

Yesterday after two continuous days of thinking about mould, on the way home I saw these ubiquitous splotches on the ground. In Singapore you often see black spots, which I find are usually either tar or dessicated slugs which have perished in the godawful heat. But in some parts of London I often see a lot of white spots. If I had to make an educated guess I would say they could be either paint splotches from the nearby whitewashed buildings, or lichen, or perhaps chewing gum. But what are they? I am not too sure. I am inclined to think that these are paint or plaster spots because lichen might not find it easy to colonize the pavement (which must presumably be regularly cleaned), and besides the obvious fact that pedestrians must be constantly disturbing the lichen, other factors such as low rainfall, pollution and dust surely also reduces the likelihood of lichen growth. But even if it is not actually lichen, I would like to refer to it as a form of "Urban Lichen".

White Spots on council slabs along Cromwell Road

Close ups

So what causes the streets of London to be covered in these white spots? Does anyone know? These were near Cromwell Road outside the Natural History Museum.


George tells me it is actually just chewing gum. Whilst I am loathe to scrape up this unhygenic material examine it in further detail (which is the next logical progression), I fear his speculation may be right. I find the notion hard to accept at first - I mean, WHY IS THERE SO MUCH GUM IN THE FIRST PLACE? HOW CAN THERE BE SO MUCH GUM BEING SPAT OUT ON ONE SINGLE ROAD? AND SO WELL SPACED OUT? - but... perhaps that is the Singaporean in me (the sale of chewing gum is illegal in Singapore). Are the streets full of unknown people's old wads of chewing gum?


Addendum 2:

Is it possible to extract high quality human DNA from very old chewing gum? Is it also possible to determine age and ethnicity from there?


  1. I remember when the void deck where I lived in Singapore was covered in those spots. And also near the train station. When chewing gum was banned, I couldn't understand why the crazy government would do so. My mum told me it was to get rid of all of those spots!

    1. Interesting! I don't recall seeing spots or must have glossed over it somehow, but I guess I didn't get out that much as a kid haha. When I was a kid I mainly had the impression that the government had banned it mainly to keep people from sticking it onto important/expensive/hard-to-replace things such as lift buttons and MRT trains, and no one wants to have to touch someone else's gum to get to another floor!