The message
from Martin Brown contains these words:

Just to clarify, oil of wintergreen - are you saying that this occurs
naturally in composted bark?

Yes. And in reasonable amounts if you choose the right species and
mostly stripped bark. It is pretty impressive to find heaps of bark
steaming in the woods in mid-winter and on a still day the smell of it
lingers in the air.

Willow, I'd guess, some willows' bark is high in salicylic acid.

--
Rusty
Open the creaking gate to make a horrid.squeak, then lower the foobar.
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