ChEMBL

Out with the dogs today I found something I had been looking for for years - Green Elf Cups, or less excitingly known as Green Wood Cups (Chlorociboria aeruginascens) a very small and elusive fungus that stains the dead wood (usually oak) it is growing in, a brilliant blue-green color. This stained wood has been prized since the middle ages for its decorative properties. This specimen had the fruiting bodies out and was quite striking. The blue-green color is due to a highly conjugated natural product Xylindein - a dimeric naphthoquinone.