The Ugliest of Mushrooms
by Elio
Figure 1. Fruit body of the hypogeous fungus Pisolithus arrhizus (Scop.) Rauschert. Specimen photographed in Central Goldfields, Victoria, Australia. Source. Frontispiece: Pisolithus arhizus (Scop.) Rauschert (1959) (side view) — Perdebal (Afrikaans) — Nature's Valley, South Africa. Source
If beauty is in the eyes of the beholder, then, faith and begorra as the Irishmen may say, so does ugliness. It is widely stated in the mycophile literature that the ugliest of mushrooms is one called Pisolithus arhizus (once tinctorius, for reasons I'll explain soon). This is an often-misshapen puffball, if a rather unusual one. What characterizes it is that its interior, which in other puffballs becomes a single mass of spores, is divided up into little sacs called "peridioles." Each sac is made at the base of the mushroom, slowly to mature and to be pushed upward. If you slice a Pisolithus vertically, you will see a progression of spore-carrying sacs, from immature at the bottom to mature at the top. This arrangement makes easy to identify a specimen. Eventually, the whole sac of the specimen breaks up, allowing the spores to be released.
Figure 2. Pisolithus arhizus growing in Yellowstone National Park. P. arhizus creates an energy-rich island refugium habitat in a thermal soil desert that harbors microbial community that is distinct from parent soils and includes deeply diverging novel lineages. Source
Members of the genus Pisolithus are usually found in dry hot areas, including deserts. A recent study describes the microbiome of P. arhizus fruiting bodies growing in geothermal areas of Yellowstone National Park. This fungus concentrates a number of metal ions, such as copper, manganese, nickel, and zinc, and produces a zone rich in oxygen. The microbiome of this environment is richer and more diverse than that of the soils nearby. Included in the vicinity of the fruiting bodies are bacterial members of the Proteobacteria (mainly Burkholderia), Gemmatimonadetes, Bacteroidetes, Verrucomicrobia, Nitrospirae, Elusimicrobia, and Latescibacteria. In the words of the authors, "Our data demonstrate that the P. arhizus system is unique to those of previous studies in several ways. Not only is P. arhizus a basidiomycete with a closed fruiting body which houses steep oxygen transitions, but the fruiting bodies also contain two additional energy sources not considered in systems studied previously. Namely, the rich hydrocarbon slurry that is present in the P. arhizus environment, and the enrichment in several elements... This unique combination of conditions and energy sources could provide insight into factors that influence microbiome community structure and dynamics and also into strategies both genomic and functional that a community of symbionts could employ to adjust to different selection pressures."
Back to the name. The older species term, "tinctorius," refers to the usage of this fungus for dyeing cloth. It can be used for making brown and golden colors. All you need to do is to boil the fungus pieces and soak the cloth in the liquid. Ugly no more!
