While walking down the path the other day, I came across a lichen that had fallen out of a tree. It looked like a small piece of coral from the ocean with its aquamarine color and tubular, branching lobes.
I picked it up to take a look and it was papery dry and light as a feather. It seemed quite delicate, and I felt I had to handle it with care to keep from crushing it. There was a small breeze and I slightly cradled it to keep it from blowing out of my hand. The tips of the tubular lobes develop into a nodule-like head called the soralia where the powdery soredia are produced, hence the common name powder-headed tube lichen. Soredia are asexual reproductive structures that contain both the photobiont (algae or cyanobacteria) and the mycobiont (fungus). The soredia will disperse and grow into a new lichen if they land in a suitable habitat.
Rhizines are fungal filaments that function to attach and hold many lichens to their substrate and don’t have vascular capabilities like the roots in plants. The Latin name of Powder-headed Tube Lichen is Hypogymnia tubulosa. Its genus is derived from the Greek words hupó, meaning “under” and gumnós, meaning “naked.” If you look on the underside of Hypogymnia tubulosa it has a blackened, wrinkled surface that lacks rhizines which is probably what this is referring to. So far in my research, I haven’t found a description of how its underside attaches itself to a substrate like tree bark.
I found a bare spot on a tree limb and nestled it between some other lichens to hold it in place. I wanted to see if it would reattach and continue to grow.
Nature is an inexhaustible source of wonder. I look forward to seeing you out there.
Sources
“Hypogymnia.” Wikipedia, 22 Nov. 2024. Wikipedia, https://en.wikipedia.org/w/index.php?title=Hypogymnia&oldid=1259003117.
Jackson, August. “Lichens of Mount Pisgah: A Field Guide to Select Species.” Nov. 2022, https://mountpisgaharboretum.org/wp-content/uploads/Lichen-Field-Guide.pdf.
Lichen Biology. https://www.fs.usda.gov/wildflowers/beauty/lichens/biology.shtml. Accessed 21 Oct. 2025.
