Lichenomphalia Umbellifera

Day 169: Lichenomphalia umbellifera fruits largely on decaying wood, inclining the casual lichenophile to dismiss it as an LBM ("little brown mushroom"), and although its finely grained, thin thallus is frequently concealed beneath mosses or other lichens as in the photo on the left, its dark pea-green colour is a clue to this species' true identity (immediately behind the fungus in the righthand image). It is one of very few lichens which exhibits a "mushroom" when it is in fruit, i.e., it is a basidiomycete as opposed to an ascomycete.

"There she goes again," you say, "using those big words. They scare me." Okay, let's break this down. Both fungi and lichens produce spores in specialized structures. Fungal spores are contained in basidia (singular, basidium). On the other hand, most lichen spores come from a similar structure known as an ascus (plural, asci). In the case of Lichenomphalia umbellifera, it reproduces like a fungus, but in its greater aspect, it has all the earmarks of being a lichen.

The fungal body emerges as a warm tan umbrella-shaped cap on a slender stipe. These age to white quite quickly, and turn up at the edges, the better to disperse the spores. They are fairly common in the Pacific Northwest.

Lichenomphalia Umbellifera

Day 151: Yesterday, we talked about an ascomycetic fungus (i.e., a fungus which reproduces like a lichen), so today, we'll switch it around and talk about a basidiomycetic lichen (i.e., a lichen which reproduces like a mushroom). I told you this was a confusing field. Now you should have a better grasp of what I meant.

Now as you know, lichens are a symbiosis of fungus, algae and yeast. The algae come in two forms: green algae and cyanobacteria ("blue-green algae"). They are the photosynthetic partner in the ménage à trois. One type or the other is always present in a lichen, and is generally obvious in the colour even though some orange and yellow lichens might make you doubt my word. This is germane to the discussion, as you'll see shortly.

You're walking down the trail, looking for cool things, and your eye is caught by a cute little creamy white or tan mushroom growing out of an old stump. It looks like a little umbrella. You can see that it has gills if you look at the underside of the cap, so your immediate assumption is that it is a fungus. You're only partly right. Lichenomphalia umbellifera produces a fruiting body which resembles a mushroom in more ways than just visually. Its spores are produced externally by basidia, specialized cells on the margins of its gills, as opposed to most other lichens whose spores are produced in internal asci.

Now you're asking, "But what makes this a lichen? It looks like a mushroom to me." That's because you're not looking at the whole picture. The thallus (the main body) of Lichenomphalia is that pea-green and eminently algal substance coating the wood from which the "mushroom" grows. Fruiting body and thallus are parts of the same whole: a basidiomycetic lichen found fairly commonly on decaying stumps in the Pacific Northwest.

Things are not always what they seem to be at first glance.

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).