Today's Puzzle - Marchantia Polymorpha, A Liverwort

Day 299: While I love to be able to track down the identity of a species in my field guides, I am equally pleased and dismayed when I cannot do so. I'm sure you'll understand why I'd be frustrated, but you might not immediately catch on to the logic involved in the enjoyment of defeat. "Why would anyone be happy they failed?" you wonder. Because, my dear readers, that failure affords an opportunity to learn.

I don't know what this lichen is. Several rosettes of it are growing in my north flowerbed, almost entirely shadowed by Hosta leaves. It hugs the ground closely. Its apothecial disks are open and some contain teeny-tiny spores or spore capsules reminiscent of those found in the Bird's-nest fungi (Nidulariales). Nothing, and I repeat, nothing in Brodo's 40-pound "Lichens of North America" resembles it, to the extent that I am at a loss to even place it in a family.

When I spotted it, my first thought was, "I've got to get a picture of that." Down on my elbows, I was able to get a better look, and noted its field characteristics before consulting Brodo for the first time. When I came up empty-handed, I resorted to stronger methods, i.e., I took a sample, cleaned it, photographed it under controlled conditions and examined it under a magnifier. With it enlarged on the computer screen, I again consulted Brodo. Nada. Not even close.

The final chapter in this story is waiting on a professional opinion. That was the next step: refer it to an expert. Maybe I missed something in that weighty field guide; maybe not. One way or another, I will learn from the experience and will be richer, not only for discovering the identity of this lichen, but for being shown points of identification I may or may not have overlooked.

Update: The mysterious "lichen" isn't a lichen at all. It's a thalloid liverwort, Marchantia polymorpha. I am grateful to Dr. Irwin Brodo, author of the 40-pound field guide to "Lichens of North America" for his personal response to my request for an identification.

What I mistook for apothecial disks are gemma cups. The "spore capsules" are gemmae, asexual propagules of the plant.