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.