Laricifomes officinalis

Laricifomes officinalis, also known as agarikon, eburiko, or the quinine conk, is a wood-decay fungus that causes brown heart rot on conifers native to Europe, Asia, and North America, as well as Morocco. This fungus is the only member of the genus Laricifomes, in the order Polyporales. The fruiting bodies grow in large conks on the trunks of trees.

There has been a history of human use of the fungus, from textiles, to ritualistic masks, and medicinal use; the name "quinine conk" is given due to its bitter taste. There is recent scientific evidence of it having potency against several viruses.

Description
These distinctive conks can be found growing out the side of or hanging off the branches of the host tree as high as 65 ft off the ground. These conks grow in a columnar or hoof-like shape, sometimes exceeding 65 cm in length and nearly 40 cm in girth, and can weigh up to 20 lb. The young fruiting bodies are soft and yellow-white, soon hardening and becoming chalky throughout. As they age, they begin to exhibit red, brown, or gray developments in coloration, cracking cubically with thick white felts visible in larger cracks. The spores are white and ellipsoidal, being released through the bottom of the fruit during warmer months. The taste of both conks and felts is bitter and distinct.

Similar species
It can resemble members of Phellinus which are blacker and prefer hardwood. Fomitopsis mounceae and its relatives may be similar, in addition to Ganoderma brownii.

Taxonomy
This mushroom is also known as Fomitopsis officinalis. DNA analyses showed that this species has genetical distance from Fomitopsis, and the name Laricifomes officinalis is favored.

The species epithet "officinalis" denotes an organism associated with herbalism or medicine.

Distribution and ecology
Lariciformes officinalis resides predominantly in old-growth forests, growing in Europe, Asia, and North America, as well as Morocco. It commonly prefers various Larix species, however it has been observed on certain species of coniferous trees in genus Pinus and Cedrus, for example.

A single "conk" usually indicates the complete infection of the tree, which can become a habitat for snag-nesting organisms.

Conservation
Because wild Agarikon is found mainly in old-growth forests, which have been subject to diseases, invasive species, and deforestation, there has been a sharp decline in habitable space for the fungus. Due to major habitat loss, as well as unregulated harvesting, L. officinalis populations are decreasing. While the fungus is particularly difficult to cultivate, there has been some promising research with inoculating larch branches. It is necessary to preserve the forests to prevent the extinction of Agarikon; though there have been suggestions of researching ex situ cultivation for the purpose of preserving the species, few locations actually protect the forests from logging, and there are conservation laws have been put in place for the fungus only in Germany, Lithuania, Poland and Slovenia.

Ethnomycology
Laricifomes officinalis, referred to as “bread of the ghosts” in local languages, was important both medicinally and spiritually to indigenous peoples of the Pacific Northwest Coast of North America, such as the Tlingit, Haida, and Tsimshian. The fruiting bodies were carved into masks, most likely with ritualistic purposes, and frequently marked the graves of tribal shamans. In addition, there is evidence that the mycelium growing in the rotting wood was being processed into textiles within these same peoples, creating a material similar in texture to leather.

Medicinal use
L. officinalis was used by the Ancient Greeks to treat consumption (tuberculosis) according to the writings of Pedanius Dioscorides in 65 AD, and by some indigenous people to treat smallpox. Later on, the conks were collected extensively for production of medicinal quinine, hence the name "quinine conk", which they were thought to contain because of the bitter taste of the powdered conk, however they do not contain quinine, nor do they possess anti-malarial properties.

Mycologist Paul Stamets has performed numerous investigations of the biological activities of Agarikon; its extracts have demonstrated antiviral activity against a range of viruses in vitro. This activity has been specifically observed against pox family viruses, HSV-1 and HSV-2, Influenza A, Influenza B, and Mycobacterium tuberculosis in vitro.

Other researchers have identified novel chlorinated coumarins in the organism which demonstrated notably low minimum inhibitory concentrations against the Mycobacterium tuberculosis complex.