Thoughts on the fascinating blue species of the Kingdom Fungi

The Color Blue in the Kingdom Fungi

By tych0_21 | MyMycoBlog | 10 Aug 2021

Despite being known as "the blue planet," our planet is host to a surprisingly few number of organisms that are capable of producing "true blue" pigments. Less than 1 in 10 flowers contain blue pigments, and for animals, the numbers are far fewer.

The colors we observe from any given plant, animal, or object are the result of the wavelengths of light that are reflected by the observed subject. For instance, we observe many plant's leaves and stems as green due to the presence of chlorophyll, a pigment that reflects green light. This being said, the majority of blue hues that we observe in nature are not the result of light reflecting from blue pigments; instead, they are the result of light scattering from microscopic arrangements of molecules and their resulting structures. For instance, the bright blue feathers of a Blue Jay (Cyanocitta cristata) are not the caused by blue pigments in the bird's feathers. Microscopic structures that adorn the feathers of the species' males instead scatter light in such a manner than only blue wavelengths are permitted to escape and reach an observer's eye.

"True blue" hues, resulting from blue pigments, rather than "structural blue" hues are exceedingly rare in nature. While the exact reason for this is unknown, it seems that altering microscopic structures to reflect blue light is a more simple evolutionary task than creating the chemical pathways to create blue pigments. Though this may seem like a inconsequential phenomena of the natural world, it is one that I personally find very interesting.

For those that have followed any of my previous posts here on the Hive blockchain and/or Publish0x, you may have gathered that I am very fond of studying fungi. While blue hues are similarly rare in the kingdom of fungi, when they do appear, they tend to appear in response to damage to a fungal fruiting body. In fact, the blue bruising of a mushroom when cut or scraped is often used as an distinguishing feature when attempting to identify a species in the field. In boletes, this reaction is often the result of acids, such as pulvinic, variegatic, or xerocomic acid, found within the fungal fruiting body, oxidizing following some physical damage to the mushroom. For those that are familiar with psilocybin mushrooms (commonly referred to as "magic mushrooms"), this bluing effect is an all too familiar result of at least 6 different blue pigments developing from the oxidation of psilocybin. As far as I am aware, if there is any evolutionary advantage to such coloration, it is unknown to science.

The next time that you come across a bluebird, blue flower, or even one of my favorite fungal species, the Indigo Milkcap, please take the time to appreciate the billions of years of evolution that had to take place for this wonder of nature to come to fruition. On the blue planet, the color blue is among of our most precious pigments.

Below are a selection of images of blue and bluing fungal species that I have come across in the woods of western Michigan, USA as well as images that are not my own of the bluing effects of psilocybin mushrooms.

Indigo Milkcap (Lactarius indigo):