Around eight years ago, on a day off from work and school, I remember strolling around the Buffalo Science Museum. Looking at all of the cool exhibits, I had found a section presenting a subset of the native flora and fauna of North America both extinct and extant. Behind a glass display, I saw a huge dried polypore fungus. I remember struggling to read its scientific name, Bondarzewia berkeleyi.
This is near the time when I was just really getting into mycology, so you can imagine how excited I was. Thinking back on this experience, it now makes perfect sense why this fungus was on display. First off, there is the shock factor in its large size. When it comes to museums, size matters. The everyday passerby would probably pass this huge polypore, making a b-line for the truly massive dinosaur exhibit. But me, no way! Comparatively, these polypores dwarf most other forest floor inhabitants. The display specimen alone was nearly two feet wide! Secondly, like many other long-lived polypores, they preserve really well. Once properly dried, their woody tissue can last for decades to come.
My second encounter was of a living specimen, nearly 6 years later, while doing field work in Southern Appalachia. Again, I was floored by its robustness. You can find this species at the base of a handful of hardwoods, but it has a strong preference for oaks. I happened to find this particular specimen at the base of a large, dead oak, a position in which I could fathom its evolved ecology. This fungus is actually a parasite, penetrating the root structures of suitable hardwoods. Once hyphae penetrate to its host’s roots, it secretes enzymes that start breaking down the inner heartwood.
The enzymatic potential of this species is quite powerful too. Natural selection has favored individuals that can quickly colonize hardwood root substrates and rapidly break down lignin into more simple sugars. Remember, those who eat compete! With its chemical competence, Bondarzewia berkeleyi doesn’t just stop at being a parasite. Already dead suitable hardwoods can be colonized by this hefty polypore, making this species a saprotroph as well as a parasite.
I see this trend in species with a generally narrow niche width. The smaller area of suitable habitat, the more spores that need to be produced for genes to successfully pass onto the next generation. For example, much of the time, tree wound parasites have long-lasting perennial fruiting bodies that produce several billion spores over the course of its lifetime. Another example is the largest gilled mushroom on the planet, Termitomyces titanicus, that makes termite mounds its home. Again, with its narrow niche of appropriate habitat it needs to produce a ton of potential offspring. Fungi with narrow ecological niches tend to have larger spore producing structures.
I have fond memories of this cool fungus that started back when the foundation for my mycological obsession was being set. What was even better than finding it in my local museum was when I got to see this fungus in action, breaking down the roots of a gigantic, dead oak in Southern Appalachia.