I touched the mushroom and it was bleeding?!

Author: Mushroom Chronicles (Engineering Research Center for Edible and Medicinal Mushrooms, Ministry of Education, Jilin Agricultural University)

The article comes from the Science Academy official account (ID: kexuedayuan)

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In nature, there is a plant called "dragon blood tree", which is classified in the genus Dracaena. The word Dracaena comes from the ancient Greek δράκαινα, which means "female dragon". When this kind of plant is damaged, it will secrete red resin, which is vividly called "dragon blood" by people, which is very strange.

Dracaenadraco (Image source: wiki)

Coincidentally, in the big family of mushrooms, there is a peculiar "member". Not only does it change color when injured, but like the dragon blood tree, it can secrete red juice. It is the protagonist of this issue - the blood red mushroom (Mycena haematopus).

The injured Mycena haematopus oozes bright red "blood" (Photo source: Mushroom Journal)

The "bleeding" mushroom will glow

Mycena haematopus, also known as red juice mushroom, was discovered by the internationally renowned mycologist Persoon in Germany in 1799. It was initially placed in the genus Agaricus, but was moved to the genus Mycena in 1871, and the name Mycena haematopus has been used ever since.

Haematopus can be divided into two parts: Haemato and pus, which are derived from the ancient Greek words αἱματο (blood) and πους (foot), respectively, so it is also called blood-foot mushroom abroad. But in fact, this name is not so appropriate, because the red juice of the blood-red mushroom often flows out of the cap. Considering the bleeding part, it may be called "blood-head mushroom" (double the horror!).

The cysts at the edge of the gills of Mycena haematopu under a microscope are essentially specialized structures of hyphae (Image source: Mushroom Journal)

So, how does the red juice of the blood-red mushroom come from? We know that mushrooms are actually formed by the aggregation of hyphae, and then some other structures are specialized on this basis, such as basidia, cysts, etc., which are also filamentous cells in nature, and the red juice of the blood-red mushroom is produced by the filamentous cells in the flesh. Generally speaking, red juice will only flow out of young and fresh mushrooms. The author has also encountered blood-red mushrooms that did not flow out red juice after being injured, but only left red marks.

The blood-red mushroom (Mycena haematopus) on the rotten wood turns red but does not ooze juice after being cut (Photo source: Mushroom Journal)

The juice of the blood-red mushroom contains a pigment called "haematopodin B", which decomposes into stable heme (haematopodin) when exposed to light in the air. This is the first pyrroloquinoline alkaloid found in fungi. This type of compound has certain cytotoxicity and antibacterial activity. It is often found in sponges and is relatively rare in terrestrial organisms, which has attracted the interest of many researchers.

The shaking blood-red mushroom (Mycena haematopus) gives people a sense of enchantment and creepiness (Photo source: Mushroom Journal)

In addition, the blood red mushroom is also a kind of mushroom that can "glow", but this luminescence phenomenon is so weak that it takes 20 hours of exposure to X-ray film to detect it. In addition to the blood red mushroom, there are many types of mushrooms that can glow, such as the fluorescent mushroom (Mycena chlorophos) that everyone is familiar with, which can emit very strong fluorescence at night.

Fluorescent mushroom (Mycena chlorophos) (Image source: https://en.wikipedia.org/wiki/Mycena_chlorophos)

The biochemical basis of mushroom luminescence is still unclear. Generally speaking, bioluminescence is caused by the action of luciferase [an enzyme that emits light through the oxidation of luciferin (a pigment)]. As for why fungi emit light, it is also an unsolved mystery. However, there are several hypotheses in academia: 1. Attract insects to help spread spores; 2. The luminescence phenomenon may only be a byproduct of other biochemical functions; 3. It may help prevent the invasion of heterotrophic organisms.

The blood-red mushroom (Mycena haematopus) infected by the mold (Spinellus fusiger) is very artistic (Photo source:

https://en.wikipedia.org/wiki/Mycena_haematopus#cite_note-Persoon1799-2)

"Studying mushrooms is a lifelong process, from a young girl to an old lady, and there is no end to it."

So, where can you see the true appearance of the blood-red mushroom?

The blood-red mushroom, which likes to grow on the rotten wood of broad-leaved trees, is actually a species that is widely distributed in the world. It is distributed in Europe, North America, South America and East Asia. In my country, blood-red mushrooms are commonly found in the northeast region. Their small, light red figures can be seen in the woods from the end of July to the end of August. Although according to the "List of Chinese Edible Fungi", blood-red mushrooms are edible. However, in some websites and papers, the description of blood-red mushrooms also says that "edibility is unknown". Adhering to the principle of "some say it's OK, some say it's not OK, then it's not OK". The author does not recommend eating blood-red mushrooms.

If you want to know more about the blood-red mushroom, you have to check its family background - the genus Agaricus.

The mushrooms of the genus Agaricus are well-deserved of their name. They are generally small in size and come in many varieties. There are currently 2,317 records on the Index Fungorum website. This is a huge number for researchers, and the number is increasing every year. Therefore, Professor Tuligul, a famous mycologist, once said: "Studying Agaricus is like studying from a young girl to an old lady, and there is no end to the research."

In the genus Mycena, there is a species that is closely related to the blood-red mushroom, called Mycena galopus, which is relatively rare in my country. It has a brown cap and likes to grow on rotten wood. When injured, its stem will secrete white juice, which is very interesting.

Milk-foot mushroom (Mycena galopus), from the photo it seems that the gills also produce milk (Photo source: https://www.museubiodiversidade.uevora.pt/elenco-de-especies/biodiversidade-actual/fungos/basidiomicetes/mycena-galopus/)

There is also a small mushroom called the bloody mushroom (M. sanguinolenta). From the name, you can tell that it is closely related to the "blood red mushroom". Its macroscopic morphology is very similar to that of the blood red mushroom, and it will also ooze red juice when injured.

The blood mushroom (M. sanguinolenta), with black edges on the gills (Photo source: https://www.mycena.no/sanguinolenta6.htm)

Some mushrooms don't change color, they are sorry for the damage they have suffered

In addition to the "blood-red mushrooms" that bleed, there are also many types of mushrooms that change color after being injured. The most famous one is the "green hand", which is a type of boletus that turns green after being injured. It tastes very good and is very popular in Yunnan, my country. However, they often contain hallucinogenic toxins, and if eaten improperly, you can see villains.

Boletus bicolor, a type of boletus that turns green when cut (Image source: http://www.mushroomexpert.com/boletus_bicolor.html)

In addition, the highly poisonous mushroom Russula subnigricans is also well-known. Its flesh and gills will turn red when injured, which is very similar to the common Russula nigricans and R. densifolia (these two mushrooms may also contain gastroenteritis toxins, and there have been reports of poisoning, see "Identification of Poisonous Mushrooms and Prevention of Poisoning"), and it is difficult to distinguish them from each other in terms of morphology. Russula subnigricans, a highly poisonous mushroom, has caused 94 poisonings and 23 deaths in Guizhou, Guangxi, Fujian and other places.

From left to right: the highly toxic Russula subnigricans, R. nigricans, and R. densifolia (Image source: https://blog.mycology.cornell.edu/2013/12/30/a-deadly-russula/; https://en.wikipedia.org/wiki/Russula_densifolia;

https://en.wikipedia.org/wiki/Russula_nigricans)

Another example is the Paxillus involutus, whose flesh turns dark brown after being cut. The book "Identification of Poisonous Mushrooms and Prevention of Poisoning" believes that it contains chronic toxins, although it has been reported as edible in some areas.

Paxillus sp., the flesh of the mushroom turns brown after being cut, and is not recommended for consumption (Photo source: Mushroom Journal)

As the saying goes, "If you don't eat mushrooms properly, the whole village will come to eat them." As summer approaches, mushroom lovers will face a "life or death" moment when eating mushrooms. In order to extend the time for individuals to enjoy the world's delicacies, it is recommended that you purchase wild mushrooms through formal channels and enjoy the gift of nature safely.

References:

[1] Baumann C, Bröckelmann M, Fugmann B, et al. Haematopodin, an Unusual Pyrroloquinoline Derivative Isolated from the Fungus Mycena haematopus, Agaricales[J]. Angewandte Chemie International Edition in English, 1993, 32(7): 1087–1089.

[2] Dai Yucheng, Zhou Liwei, Yang Zhuliang, et al. List of edible fungi in China[J]. Journal of Mycology, 2010, 29(01): 1–21.

[3] Chen Zuohong, Yang Zhuliang, Tuligul, et al. Identification of poisonous mushrooms and prevention of poisoning[M]. Science Press, 2016.

[4] Wikipedia https://en.wikipedia.org/wiki/Mycena_haematopus#cite_note-Baumann1993-34

[5] Mushroom Expert https://www.mushroomexpert.com/mycena_haematopus.html