The Silver Birch; or, This is Not a Shrunken Head
Created | Updated Oct 21, 2023
The Silver Birch; or, This is Not a Shrunken Head
The following is an actual email conversation that took place over two days.
Paigetheoracle: Saw this knob stuck on a tree, with lichen hanging from it.
The subject line read: Shrunken head?
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DG: Knob of what? Stuck on the tree how? I know these are words. They convey no meaning to my mind. Also, I see this, but do not understand it.
This, I realise, was bad of me. But h2g2ers who are not Willem (a plant specialist) sometimes fail to take into consideration that my experience of flora may not overlap with theirs – nor does my mind automatically run in the same channels. I am hoping for genus, species, and habits of the arboreal object in the photo. This is what I get.
Paigetheoracle: It's a growth on the side of the tree. Shrunken heads have occasionally appeared in films and soft plastic versions were common in sixties Britain as a sort of decorative fashion statement. Head hunting occurred in South America and /or Indonesia (not sure). You know what lichen is I presume. Anything still not clear? Talk to the hand as it waves goodbye from the other side of the ocean.
The only thing I have learned from this that I actually wanted to know is that the knob grew on the tree. (From the photos he sends, it was not entirely outside the realm of possibility that the locals had nailed it there.)
I will now pass by in silence the emails that ensued on the subject of shrunken heads. He sent me a graphic description of the process, adding that he hoped I wasn't eating. I knew this to be a lie: obviously, he hoped I was eating. Of course I was. I countered with a story about a missionary I knew as a kid who had us all exclaiming in disgust at the 'shrunken head' he passed around, which he admitted was made of rubber. This went on for a while. I let him have the last word by not replying.
This was a mistake. The next day I got a new email:
Subject: Did You Get the Email?
Paigetheoracle: The one telling you that it was a growth on the side of the silver birch tree, plus stringy lichen like the photo I sent you?
Reply: Yes, I did. I just didn't have anything to say about it at the time. I will have to look up silver birches and see why they get growths on them.
Aha. Your silver birch has tree cancer.
As it turns out, Betula pendula is a Eurasian tree that is considered invasive in some parts of North America. Some people like it because it is a good shade tree; on the other hand, it frequently harbours aphids that drip something called honeydew, which makes a mess. Also, it can trigger allergies, so there's that.
An injury, virus, or fungus can cause the silver birch to form a burl, which is the technical term for that round growth. I don't know the name of the lichen for sure: it may be Ramalina subleptocarpa. Willem can probably tell us. It seems to be a fructicose lichen.
And yes, it's hanging there like stringy hair on that burl. A very weird person might be tempted to think about a shrunken head. Just not while I'm eating, please.
