Day 106: Just as I was about to start celebrating a second location for a different Hypogymnia ("tube lichen"), I said to myself, "Hang on a mo'...the medullary ceiling was dark, not white. That means it's..." (I grabbed the 40-pound field guide) "...it's inactiva." The narrow-lobed Hypogymnias are easy to confuse without that crucial datum, so I was glad I'd checked. No, I honestly don't have all the information committed to memory. I rely on books and other resources almost on a daily basis, whether it's for lichens or vascular plants. That said, there are different things to check for between genera in the field, e.g., presence and type of fruiting bodies, branching, base colour, whether a podetium (stalk) is hollow or solid, and those are the things I keep in mind when examining a specimen. Even then, it's all too often that I won't be able to differentiate species simply from macroscopic characteristics. If I can get "close enough for gov'mint work," I'm happy. With Hypogymnias, one of the most helpful field identification points is the colour of the medullary ceiling, so when I found this one, I pinched off one small lobe and peeled it apart. Hypogymnias are called "tube lichens" for a good reason. Their lobes are hollow, like balloon animals. Separate the blue-green top from the black lower surface, and the telling point will be what colour is on the inside of the top layer. If anyone had been close by, they would have heard me apologize, "Sorry, sorry. I can't tell who you are without doing this. Sorry!" as I nipped off an inch with my thumbnail. Yes, seriously.
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