Finding Hypoxylon Fuscum

Day 149: I have often remarked to friends that I have no need or even particular desire to travel to foreign lands because there is so much to see right here in the Pacific Northwest. Almost every time I go out, I stumble across something new or odd, whether it's a species I haven't previously observed or a morph/sport/aberration of something common and familiar. My "score" from yesterday's four-mile walk was Hypoxylon fuscum, and for that identification, I have to thank a slime mold expert who set me straight on its fungal nature. I'd hoped for a new slime. Nope, it's a fungus.

Hypoxylon is a pioneer, one of the first fungi to colonize the decaying wood of its chosen host. It disappears rather rapidly once it has invaded the cell structure and broken it down into a form more readily used by other fungi like the Tremellaceae which are frequently associated with it. Unlike most other fungi which are basidiomycetes, i.e., their spores are formed externally, it is an ascomycete, i.e., its spores are contained in internal capsules called asci (singular, ascus) like those in most lichens. Just as a sidebar here, it should be noted that there are a few lichen genera which are basidiomycetes (Lichenomphalia for one), exhibiting a mushroom-like fruit which sheds spores from its gills. Likewise, there are other fungi which are ascomycetes. Confused yet? Please remember that lichens are a symbiosis between fungus, algae and yeast. Hypoxylon is purely fungal. This species (Hypoxylon fuscum) is one of two known from Washington, hosted by Red Alder (Alnus rubra).