Green Elf Cup

As a professional botanist, I don’t know my mushrooms well, but I am working to learn more.  This fall, I’m sharing some easily identified, beginner-level species so you can learn too!  Today’s fungus is not only strikingly beautiful but has also been prized by woodworkers for centuries.  This is the lovely Green Elf Cup (Chlorociboria sp).

Photo 1: Fruiting bodies of Green Elf Cup on PEI.

I’m fascinated by coloured fungi.  With plants, colours usually serve some specific purpose: green chlorophyll makes food from sunlight, bright flowers attract pollinators, drab seeds hide from predators.  But fungi don’t care about photosynthesis, pollination, or predation so why bother being colourful?  In the case of Green Elf Cup, the colour is due to a unique chemical called ‘xylindein’ that may help the fungus by deterring termites as well as other, potentially competing, fungi. But in producing xylindein, Green Elf Cups do something humans cannot: despite extensive research, scientists have not yet been able to synthesize this pigment.

Photo 2: The distinctive turquoise-stained wood, evidence of Green Elf Cup mycelia.

A mushroom is just the fruiting body of the fungus; the organism itself is a mostly unseen thread-like network of mycelium growing within the wood or soil.  Green Elf Cup gets its name from the cup-like fruiting bodies that appear on dead hardwood (Photo 1).  Unlike most fungi, with Green Elf Cups you are more likely to spot the mycelium which shows up as distinctive, stained wood (Photo 2). 

Green Elf Cup-stained wood has been used decoratively since at least the 1400s.  It grew in popularity in England in the late 1700s with the development of Tunbridge Ware – intricate inlaid products made from mosaics of different coloured wood (example, Photo 3).  Known as ‘spalting’, the fungal pigmentation remains highly sought after in woodworking circles and is one reason researchers would like to be able to synthesize the colourful xylindein. 

Photo 3: A Tunbridge Ware box from the early 1800s. The colour in the lid is spalted wood, pigmented by Green Elf Cup (image source: The British Antique Dealers Association).

Beauty is not the only economic attribute of Green Elf Cup and xylindein.  The pigment is an organic semiconductor, and has potential uses in devices such as LED’s, solar cells, and fiber optics among others.  Research is ongoing to figure out how to produce xylindein synthetically, as well as how to culture Chlorociboria species to both grow quickly and produce the most high-quality xylindein.  These fungi could play an important role in some of the leading technologies of our time.

Green Elf Cup is common in hardwood and mixedwood forests across PEI.  As one of the soft rot fungi, it plays an important role in nutrient cycling, including in conditions that aren’t suitable for white or brown rot species.  I’ll leave the chemical and physical research to the experts but will appreciate the ecological role and biological beauty of this part of PEI untamed!