Friday, January 10, 2020

Physcia Adscendens


Day 89: Well, I can't count this one as a life-list species because I was introduced to it on a field trip with Katherine Glew, but it was the first specimen of Physcia adscendens I've found on my own. It's recognizable by helmet-shaped lobe tips as well as having "eyelashes," and although you can't tell from the photo, it is quite small. The lobes are under half a millimeter wide, and the whole lichen does not exceed two centimeters in diameter. How did I find it? When I am out shopping as I was today, I always try to park next to a tree so I can find my car again. Cars are so hard to identify! Most of them are silver-grey in colour, and 99% of them have four black tires, white lights in the front and red ones in the back. I do not have a Field Guide to Common Vehicles, and since I don't usually carry my GPS when I go in town, I frequently spend an inordinate amount of time studying license plates in the hopes of coming across the distinguishing feature which sets mine apart from the others. And yes, I have tried to get into one belonging to someone else. Fortunately, there were no consequences attached to that event. On the other hand, a tree is something I will recognize, even from a distance. I pulled up to a small ornamental which was lavishly covered in green and gold lichens. "Xanthoria!" I said, "But what's the grey-green stuff? That's not a Parmelia." I took the main photo in the composite above and then broke off two small pieces in different stages of development. I sat for a few minutes in the car examining them before driving away just in case I needed a larger sample, and that was when I discovered the "eyelashes." Thinking back on recent finds, I assumed Parmotrema, but when I got home and put the specimens under magnification, I realized I was off base. Eventually, having gone forward and backward through several dichotomous keys in both Brodo and McCune, I narrowed it down to two choices: Physcia adscendens or P. tenella. The shape of the soredia-bearing lobe tips and absence of apothecia clinched it: adscendens, predictably the more common of the two. I'll never forget that tree now, even if I can't remember where I put my car or if the person I just spoke to had a moustache or wore glasses. Priorities. You just gotta keep 'em straight.

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