Parmotrema Eyelashes

Day 32: Wishing I had brought a hand lens, I was bent over with my nose to a wooden hand rail at Billy Frank National Wildlife Refuge analyzing what I thought might be two different species of Parmelia growing side-by-side when the broader, flatter lobes of a third lichen caught at the corner of my eye. A closer look revealed black "eyelashes" (cilia) along the margins. Eyelashes! I'd found my first Parmotrema (never mind that I've walked past it dozens of times over the last several years). I carefully lifted a small piece and laid it on the back of a maple leaf to provide contrast for the inset photo. When I got home, I discovered to my dismay that I was not going to be able to obtain an identification from my sample without a UV light. Parmotrema chinense does not fluoresce, but P. arnoldii does. Otherwise, the two are morphologically identical righ down to the broad tan margin on the back of the lobes, and the two species' ranges overlap in coastal/maritime riparian forest.

Scientific method precludes the tossing of a coin, so I resigned myself to filing it under "Parmotrema sp." In fact, I had begun writing this post before I remembered that my best hand lens (the one I never take into the field) is in fact equipped with a UV light. I pulled my sample out of the wastepaper bin on my desk. Hurrah! It fluoresces like a a hippie's interior decorating. I present to you herewith a confirmation of ID: Parmotrema arnoldii.