Hypoxylon Fuscum

Day 110: When I first encountered Hypoxylon fuscum, I mistook it for a slime mold, an understandable error when you consider its appearance. However, it is fungal, specifically a saprobic "decomposer" which feeds on decaying wood. Its preference for Corylus as a substrate led to the common name of "Hazel Woodwart," but it can affect other hardwoods, and in this instance was growing on Red Alder (Alnus rubra). Its fruiting bodies form clumps which, when fully mature, resemble black raspberries in both size and configuration, but may be white or tan when young. Individual stromata are 2-5 mm. in diameter and 0.5-2 mm in height.

Let's step into the other room for a moment to talk about words. As with most scientific disciplines, botany has its own vocabulary which breaks into even smaller subsets with each specialty. Technical terms can be daunting ("stromata," "saprobic"), but the heavy use of Latin is a stumbling block many people find it difficult to surmount. As I have mentioned before, it becomes easier when you can relate a Latin name to an English word, so let's break "Hypoxylon fuscum" into its component parts.

First of all, there is "hypo-." It means "under" or "beneath." You know what a "hypodermic" does. It puts a medicine under ("hypo-") your skin ("-dermic," from "dermis," i.e., "skin"). "Xylon" also provides an English word, although it's botanical: the xylem layer of a tree contributes to wood formation, "xylon" meaning "wood." As for "fuscum," the root word brings us "obfuscate" which, while it may not be in your everyday vocabulary, you know means to cloud or obscure an issue. "Fuscare" means "to darken," hence "fuscus" means "darkened" or "blackish." And now that we have all that sorted out, I'll leave you to think about what you've learned today.

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).