Common Name: Artist’s Conk, Giant Shelf Fungus, Tree Tongue, White Mottled Rot Fungus, Kofukitake (Japan), Flacher lackporling (Germany), Трутовик плоский (Russia – pronounced Trutovik ploskiy) – The white pore surface stains brown when compressed according to the applied pressure creating an image that persists in perpetuity; it is a natural artist’s canvas. Conk is a term for any fungus that is attached to a tree like a bracket – an architectural shelf support.
Scientific Name: Ganoderma applanatum – The generic name is a combination of the Greek words gano which means ‘brightness’ and derma meaning ‘skin.’ G. lucidum, which has a shiny upper surface, is the type or characteristic species for the genus. The name applanatum is derived from the Latin planum meaning ‘plane’ to describe the flat, bracket configuration of the fungus.
Potpourri: The Artist’s Conk is a global species that subsists on both hardwood and coniferous trees as a parasite when they are alive, sometimes killing them, and as a saprophyte when they are dead. It is a white rot fungus, consuming both the structural cellulose and the binding lignin of the wood (the alternative brown rot fungi degrade only the cellulose, leaving brown, block-like chunks). The plurality of common names is evidence of their presence on every continent except Antarctica – which, among other things, has no trees. It is readily recognizable for its ceramic-smooth, white-pored underside and for the wrinkled brown cap surface – like the furrowed brow of Tolkien’s Treebeard; it is nearly as old. The perennial G. applanatum can live for over fifty years.
The notoriety of G. Applanatum is due in no small measure to its canvas-like pore surface, an artist’s easel that needs no paint. As is the case with many of the fungi, the application of pressure causes a color change, in this case from white to brown (known as ‘staining brown’ in the lexicon of mycology). What is unusual about the Artist’s Conk is that the delicate application of pressure with a blunted stylus results in gradations of brown that can produce the chiaroscuro effects of portraiture – so much so, that, according to In the Company of Mushrooms by Elio Schaechter, “A church in the Mexican state of Puebla, Nuestra Señora del Honguito, is dedicated to a fragment of Ganoderma showing what is believed to be the image of Christ on the cross.” While religious pareidolia is not uncommon, this may be its only manifestation with a fungus, presumably invoking Mother Nature as the artist. Remarkably detailed scenes can be created with a modicum of effort and a little imagination – it is indeed the Artist’s Conk.
The almost vitreous smoothness of the pore surface is due to the miniscule size of the pores, which are impossible to visibly discern without magnification; their 200 micron diameter is about twice the width of a human hair. The large collective pore surface area combined with the small individual pore size results in many pores – which produce a barrage of spores. According to David Aurora in Mushrooms Demystified, a large Artist’s Conk “liberates 30 billion spores a day for 6 months of every year, or more than 5,000,000,000,000 (5 trillion) spores annually.” The astronomical spore count relative to the paucity of mature conk fruiting bodies is ample evidence of the infinitesimal probability of a single spore succeeding in reproduction. The billions of brown spores permeate the air around the fungus as they are carried by the wind in all directions, including up. The envelopment of brown spores results in the cap surface becoming haggard with age, an ‘old-man-of-the-woods’ in both age and appearance. Stobilomyces floccopus is called the old-man-of-the-woods due to its shaggy, scaled and venerable looking cap surface but it is an ephemeral, bolete-type pored mushroom that rises from the ground only on occasion and has longevity of weeks, not years.
Ganoderma applanatum is a polypore (literally many pores), which is a general term that refers to the presence of pores (instead of gills) on the underside of the cap in a bracket or shelf presentation (boletes have pores but have the cap and stem mushroom configuration). Polypores have traditionally been placed in the order Polyporales, the family Polyporaceae and the singular genus Polyporus. However, the systematics of the polypores has been subject to significant revision to the extent that there are now about 50 genera of ‘polypores’; those that remain in the genus Polyporus are, according to Gary Lincoff in the Audubon Field Guide to Mushrooms, “annual and stalked, with pale-colored flesh and cylindrical, colorless spores.” The confused taxonomy of polypores is evident in the variety of scientific names that have been used for the Artist’s Conk. In addition to Ganoderma applanatum, Polyporus applanatus, Boletus applanatus, Fomes applanatus, Fomes vegetus and Elfvingia applanatus have been used and are still found in some references.
The types of hyphae are one of the key taxonomic determinants to the new genus assignments for the once predominant Polyporus. The hypha is the essence of a fungus; it grows from the originating spore and extends in a filamentous tendril in search of nutrients much like the roots of a plant. As hyphae that are “sexually compatible” meet, they combine their nuclei in a double-nucleus cell called a dikaryon and separate into segments as they grow; a configuration that is called septate. The plexus of the many hyphae form the epigeal body of the fungus which is called the mycelium. Polypores are made up of three types of hyphae: generative, skeletal and binding. Generative hyphae are as described above in that they grow in the assimilation of nutrients. Skeletal hyphae are thick-walled and are not separated into segments (non-septate); they provide rigidity to the -polypore. Binding hyphae are also non-septate, but are thin-walled to intertwine with just the generative hyphae, or with both the generative and the skeletal hyphae. Polypores can therefore be monomitic, dimitic or trimitic. Monomitic fungi that have just generative hyphae are relatively soft and pliable, such as the White Cheese Polypore (Tyromyces chioneus). Dimitic polypores that consist of both generative and binding hyphae are also pliable and soft, but they can be broken into segments readily, such as the Chicken-of-the-Woods or Sulfur Shelf (Laetiporus sulphureus). Dimitic polypores that consist of generative and skeletal hyphae are very hard and tough – The Artist’s Conk is a prime example. Trimitic polypores in which all three types are present have some pliability when they are young but grow stiff and rigid with age such as the Turkey Tail (Trametes versicolor).
Ganoderma Applanatum is not considered an edible fungus, as its dimitic skeletal hyphae make it too tough for human consumption. This is apparently not the case for our fellow primates. In the book Gorillas in the Mist, Diane Fossey offers the observation: “Still another special food (for the gorillas) is bracket fungus (Ganoderma applanatum)… The shelf-like projection is difficult to break free, so younger animals often have to wrap their arms and legs awkwardly around a trunk and content themselves by only gnawing at the delicacy. Older animals who succeed in breaking the fungus loose have been observed carrying it several hundred feet from its source, all the while guarding it possessively from more dominant individuals attempts to take it away. Both the scarcity of the fungus and the gorillas’ liking of it cause many intragroup squabbles, a number of which are settled by the silverback, who simply takes the item of contention for himself.” As the behavior of animals in the wild is governed by the successful adaptations that have withstood the test of time, the observed attraction of the impenetrable conk to the gorillas must be based on its taste or aroma. These sensory perceptions did not transfer to the Homo sapiens branch of the primate tree, as the Artist’s Conk is rock-hard and, when ground up and made into a tea, has a taste that is at best a bitter taste described as earthy. Or perhaps there is another reason – to promote gorilla health. This is not as far-fetched as it sounds.
The fungi of the genus Ganoderma are noted for their historical use by the various peoples of Asia. Ganoderma lucidum is known in China as either Ling Zhi or Ling Chi; the word ‘Ling’ in Chinese translates with some license to ‘spiritual, miraculous, and/or divine,’ intending to convey its efficacy and provenance. In Japan, G. lucidum is called Reishi, which means something like ‘auspicious plant’ or ‘immortality plant,’ and also Mannentake, which translates to ’10,000 year mushroom.’ This latter term is a metaphor for increasing the life of the person and not to the life of the fungal fruiting body, which lasts for just one season in one year. This is not the case with Ganoderma applanatum, which is sometimes called the ancient Reishi due to its near sexagenarian longevity. There is no indication that the Artist’s Conk was historically used for medicinal purposes by ancient peoples (gorillas don’t count); however, relatively recent research has revealed that this was a matter of omission and not commission. The ancient Reishi has been shown experimentally to have potential as an antibiotic to deter bacterial infections, as an agent to inhibit the growth of tumors, as an antioxidant, and as a treatment for diabetes.
The increasing virulence of drug resistant bacteria coupled with the dearth of antibiotic research and development is one of the existential concerns of modern society, a pandemic in the making. Fungi in general and Ganoderma applanatum in particular offer some hope in this regard. An article in the Journal of Biomedicine and Biotechnology in 2014 found that an exopolysaccharide preparation from G. applanatum (called GpEPS) resulted in 82.8% cell damage to the bacterium Vibrio fisheri (associated with seafood poisoning) and “showed antibacterial properties against the S. aureus strains”. Staphylococcus aureus is one of the primary concerns of the U. S. Centers for Disease Control (CDC) due to its ubiquity and due to its history of becoming increasingly drug resistant. Staph infections were originally treated with penicillin after the “miracle drug” (which is also a fungus) was discovered in 1943; now 98% of S. aureus is resistant. Newer antibiotics, first methicillin, then glycopeptides and now Vancomycin have all been compromised by bacterial mutations that result in antibiotic resistance. Further fungal research is clearly warranted in the interest of epidemiology.
The so-called War on Cancer that began auspiciously with the National Cancer Act of 1971 has become a synonym for bureaucratic hubris; Forty years later it is still the primary cause of death for people of middle age and older. Coincidentally, the seminal paper “Antitumor polysaccharides from some Polyporaceae, Ganoderma Applanatum” appeared in the Chemical and Pharmacological Bulletin that same year. Polysaccharides are long chains of hydrocarbon molecules that are the primary constituents of the chitin that forms the cell walls of fungi (another polysaccharide forms the cellulose of plants). In the case of G. applanatum, the polysaccharide β-glucans has been shown to stimulate macrophages which kill the tumor cells, and, probably more importantly, inhibiting the formation of new blood vessels (called angiogenesis) which the tumor requires for growth. The gorillas probably already knew this.
Hiker's Notebook 