|Common Greenshield - Flavoparmelia caperata|
I'm fairly confident of my identification. It's based on the following features:
- the overall shape, texture, color and size matches the pictures in my books.
- it grows on bark
- under a dissecting scope I saw numerous grainy-looking warts ("coarsely granular soredia from pustules").
- the underside is black with the edges brown.
- there are a few small, black unbranched rhizines (rooting structures) on the underside.
- the chemical tests matched, mostly . . .
Whatever the results, it's an enjoyable process. You might wonder why I find it enjoyable, it seems like an odd pastime I suppose (though if you're reading this blog you can probably see how). For me it's like doing a puzzle and it's the joy of learning. And there is the occasional insight or new perspective on the world; another small piece of the puzzle falls into place making the picture clearer.