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Luminescent Panellus/Bitter Oyster - Panellus stipticus

Good afternoon, friends, and happy Martin Luther King Jr. Day.

This week's mushroom is Panellus stipticus, commonly known as the luminescent panellus or the bitter oyster. These mushrooms were found in the ramble on 12/28/31.

Panellus stipticus

Fun Facts

As I teased last week, this mushroom is bioluminescent. Unlike the two Armillaria species we just featured that have bioluminescent mycelium, the actual mushrooms of P. stipticus (specifically the gills) glow in the dark. I harvested the mushrooms pictured above but they dried out too quickly before I could see their bioluminescence. Evidently, if I rehydrated them in water or with a damp paper towel, I may have yet been able to see them glow. The best way to observe the phenomenon is to bring the mushrooms - fresh and still attached to the wood if possible - into a completely dark room and allow a few minutes for your eyes to adjust to the dark. Here is a video from the sixth reference - a blog from Kathie Hodge at Cornell - that depicts the bioluminescence. If you're interested she also details in the blog how she uses this mushroom as a comforting nightlight.

There are over 70 species of fungi that are known to be bioluminescent. P. stipticus glows in the dark because of an enzyme called luciferase - which breaks down the chemical luciferin. It has recently been discovered that this bioluminescence is aligned with a natural circadian rhythm so the luciferase enzymes are active at night. This circadian synch suggests that bioluminescence is an evolutionarily advantageous feature. The hypothesis is that the glowing gills of P. stipticus attract insects to the mushroom so that its spores are then dispersed by these insects onto new substrates throughout the forest. Interestingly enough, only P. stipticus mushrooms from eastern North America glow in the dark. This species can serve as an important educational tool to understand why bioluminescence evolved in some species - or even subspecies - of fungi and not in others.

Additionally, the species name is derived from the word "styptic" which - as a noun - means a substance with the ability to stop bleeding. This mushroom has traditionally been used as an astringent, similar to Fomitopsis betulina, and although I couldn't find confirmation I imagine it is used topically rather than ingested.

Panellus stipticus


P. stipticus is saprobic, growing from dead hardwood and causing a white rot. It is found in North America, Europe, Asia, and even down in Australia. It grows spring through fall and even over the winter in warmer climates. The featured mushrooms popped up at some point during our mild December and you can see there are juvenile mushrooms still sprouting. It can take as long as three months for a single mushroom to reach maturity so some of the baby shrooms in the first picture may not be releasing spores until the spring, while the mature mushrooms were releasing spores in December and perhaps even earlier. The picture below shows the relatively diminutive size of these mushrooms but the clustered and shelved (overlapping) growth pattern is a good identifying characteristic of the species.

Panellus stipticus

We'll see if these clouds break and we can see the full moon tonight,



1) Kuo, M. (2017, May). Panellus stipticus. Retrieved from the MushroomExpert.Com Web site:


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