Mark Bower sent me these pictures of bioluminescent mushrooms, something that each of us has been trying to see for years. I can remember standing in a dark bathroom on two occasions with a number of other people waiting for our eyes to adjust to the dark and eventually giving up when there was no glow. Below is his story.
Mark Bower
I collected these Bitter Oysterling mushrooms, Panellus stipticus, a very common species in this area. It can be found year-round growing in groups on dead hardwood, as it is a decomposer. From the top it looks like many other small, boring brownish fungi. The undersurface is slightly more interesting, and is characterized by gills which terminate abruptly where they meet the small knobby stem. They also have cross veins which are easily seen in the mature specimen below.
This mushroom is known to be bioluminescent, although I was skeptical, since I had wasted many hours sitting alone in a dark closet staring at and trying to photograph these things, without success. When I tried this time I was shocked to see a greenish glow emanating from the little fungi. I became apoplectic when an image actually appeared on my camera. I’m still experimenting, but I believe the essential ingredients in photographing bioluminescent fungi are: 1) total darkness 2) long exposure time (30 seconds in this case), which requires a tripod 3) wide open aperture 4) very high ISO (as high as your camera goes). The other essential point is that not all of them glow, even ones growing in the same cluster.
The Bitter Oysterling (British origin) contains an astringent which constricts tissues and definitely makes you “pucker” if you taste it. It also can stop minor bleeding since it constricts blood vessels. The species name P. stipticus refers to this anti-bleeding property. Some may remember the styptic pencils we used to stop bleeding when we lacerated our faces while shaving.
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Of the 100,000+ documented fungal species, only 71 are known to exhibit this luminescence. So why had this trait evolved? Mark sent me this research article from Current Biology on bioluminescent fungi that throws even more light on the subject.
Anderson G. Oliveira and his associates studied a Brazilian species and found that the bioluminescence from the mycelium of Neonothopanus gardneri is controlled by a temperature-compensated circadian clock. This would conserve the energy needed to produce produce the luciferase, reductase, and luciferin that create the luminescence. The chemistry is described in the video at this Verge.com link.
Now the question was why had it evolved this complex on and off cycle and here is where it gets cool. They created "prosthetic acrylic resin ‘‘mushrooms,’’ internally illuminated by a green LED emitting light similar to the bioluminescence of N. gardneri and an identical set without the LED lighting. They found the "bioluminescent" mushrooms attract staphilinid rove beetles (coleopterans), as well as hemipterans (true bugs), dipterans (flies), and hymenopterans (wasps and ants), at numbers far greater than dark control traps.
They postulate that the circadian control may have evolved to optimize energy use for when bioluminescence is most visible, attracting insects that can in turn help in spore dispersal, thereby benefiting fungi growing under the forest canopy, where wind flow is greatly reduced. So it all comes down to reproduction for this species although not all glowing species attract insects. Stay tuned for more research.
Still curious? Check out 10 Cool Facts About Bioluminescent Mushrooms (and Where to Find Them).