Hikin’ with Lichen

There are times to go fast and times to go slow.  Recently I headed off for the Catskills with the goal of bagging a few more peaks for my record of barefoot ascents.  It had rained earlier in the morning and was still cloudy, but the rain had let up, the winds had calmed, and the temperature hovered in the mid-50s — conditions which encourage a person to relax, move at a more leisurely pace, and take in the sights.  In no particular hurry, I was sauntering up the gravel road that leads to the saddle between Bearpen and Vly mountains, looking down at the ground to avoid stepping on sharp rocks, when I noticed a small green ball of puff lying on the ground.

Upon closer inspection, the ball of puff turned out to be a form of Usnea lichen (best guess being Usnea Mutabilis), also know as beard lichen or tree moss, which commonly grows on bark or twigs.  Presumably this lichen had fallen from a nearby tree, but as I scanned the branches above, there were no signs of friends or neighbors.  Its origin was a small mystery.  It might have fallen from the sky.

I continued along the trail, enjoying the mild temperature, and finding the rocks not quite as painful as the last time I had been out this way.  A little while later a bit of green speckle caught my eye.  Bending over, I found a piece of bark covered with a foliose lichen (foliose refers to the leaf-like lobes).

What’s interesting about lichen is that the closer you look, the more you see.  Enlarging this photo, the lichen’s green-gray color results from a series of olive-green ridges and dots that rise above a milky background.  I think it might be hammered shield lichen (Parmelia sulcata).

I kept walking, and now there was a small branch lying in the path, radiating pale green.  With just a glance, I knew this was Flavoparmelia carperata, or common greenshield lichen, which is indeed very common in the Catskills, where many of the trees are wrapped head to foot in ghastly green shrouds.  That’s actually a good thing.  Lichens don’t do well in polluted environments, which is why you don’t see many in the cities, so when they’re abundant, you can breath deeply, because the air is clean and pure.  This specimen seemed exceptionally healthy, with thick lobes spreading luxuriously in all directions, glowing white and green.

With every few steps, I encountered another piece of lichen lying on the trail.  It felt like it was raining lichen.  Or put differently, these lichens were on the move.  Every time a branch or piece of bark breaks off a tree, it’s a chance for the lichens to go along for the ride and hopefully find a new habitat where they can continue to grow and spread.  Lichens can also reproduce via spores, but this is an iffy proposition, because lichens consist of fungi and algae combined in a symbiotic relationship.  For the fungal spore to produce a new lichen, it must encounter its algae partner at just the right moment.  Much easier, it would seem, to spread through bits and pieces cast adrift.

After a little while, I reached the saddle on the ridge and began scouting for the route to Vly.  It wasn’t hard to find.  The route is an unofficial, but very obvious footpath, which follows a series of blazed trees that mark the boundary between state and private land.  As the path headed up the steep slope toward the summit, I found myself stepping over some large rocks, many of which were splotched a dull gray-green.  From afar, these splotches didn’t seem remarkable, but my phone has a 5x magnifier app, and the magnification revealed small black disks, which are called apothecia and contain spores, and which allowed me to identify this lichen as concentric boulder lichen (Porpidia crustulata).

Soon another rock came into view, this one cloaked in moss and lichen.  Two puffy-looking lichens caught my eye, one green and the other white.  They were stiff and prickly to the touch.  I would have identified these as reindeer moss (which is actually a lichen) or perhaps antler lichen, but under magnification they have little leaf-like structures called “squamules” that aren’t characteristic of those species.   It would appear this is “Many Branched Cladonia” (Cladonia furcata).

The next day I would discover enormous quantities of the puffy, prickly green variety while hiking Fir Mountain.  It was especially thick on the northern slope of the mountain, growing on the ground in great clumps and also at the base of birch and beech trees, in some cases mixed together with mosses, including cascades of splendid feather moss, creating patterns of subtle contrast in color and texture.


Around the next bend in the path, another lichen was waiting for me, splashed like white paint across a large sandstone boulder.  This is called a “crustose” lichen, as it grows in the form of a crust.  Close up you can see that the lichen is cracked (this is called “areolate”)  and covered in some places with clusters of little bumps that might be reproductive bodies.  I’d like to call it “whitewash lichen,” and indeed there is a species with that name, although it is typically described as growing on trees.  The best guess is Porpidia tuberculosa, but regardless, if you’re hiking in the Catskills at night, you’ll find that this lichen practically glows in the dark.


And then there was another flash of white, although this time a bit smaller and with a faint blue tinge.  A close look revealed a pattern of light blue-colored apothecia, those small disks containing spores, which identifies this as “Smoky-eyed Boulder Lichen” (Porpidia albocaerulescens).

When I finally reached the summit of Vly, I vowed to stop taking pictures of lichen.  If I stopped dawdling, there’d be time to make it back down Vly and then over to Halcott Mountain, only a few miles down the road — but only if I moved with a sense of purpose.  And so I put away the phone, at least for a little while.  But a couple of hours later, as I approached the summit of Halcott, I discovered smooth rock tripe lichen (Umbilicata mammulata) covering a boulder, but this time in green, instead of the chocolate brown I’m used to seeing in the Shawangunks.  My friend John Franklin explained to me that lichen contain alga or cyanobacteria inside the fungus that creates food for both the alga and the fungus through photosynthesis. Photosynthesis cannot take place in the lichen without water present so when lichens are dry, the upper fungal surface is in “protection mode” creating a dark and durable UV resistant sun-screen barrier to protect the fragile alga hidden within the lichen. It can stay this way for very long periods of time.  When lichens get wet and photosynthesis becomes possible, the upper “fungal” surface of the lichen changes from “protection mode” to “transmission mode”. It specifically becomes more transparent to allow the sunlight to pass through to the green chlorophyll hidden inside. When the sun comes out, photosynthesis occurs and the lichen makes food again. This is why lichens are green when wet or damp: you actually see the chlorophyll. 

The rock tripe lichens consist of disks of flapping skin, which attach to the rock face at a single point.  They cluster on the rocks in large numbers, looking a little bit like colonies of bats hanging from the wall of a cave.  During my hikes in the Gunks and Catskills, I’ve also encountered plated rock tripe lichen, which is covered in dimples, frosted rock tripe lichen, which has a crystalline white center, and a cousin called common toadskin lichen, which has similar leafy folds but is covered in a mixture of knobby-looking bumps and small black disks.

Smooth Rock Tripe Lichen (Umbilicaria mammulata)
Smooth Rock Tripe Lichen in green
Common Toadskin Lichen (Lasallia papulosa)

Bushwhacking through the forests is a slow endeavor, especially barefoot, and since you’re watching every step, there’s a tendency to be looking downwards.  A whole new world comes into focus, full of creatures that dwell along the ground — lichen, moss, club moss, ferns, grasses, flowers — and the more you look, the more you see and learn.  As for myself, noticing new patterns in these wild mountain forests makes me feel more at home, and I think this will help when the time comes to pick up the pace again.

Thank you to John Franklin, amateur lichenologist, for help in identifying the species

Hikin’ with Lichen

3 thoughts on “Hikin’ with Lichen

  1. Irwin Brodo says:

    That’s a great story, with excellent photographs and pretty accurate IDs. Congratulations! A hike up a mountain (or anywhere), barefoot or well-booted, is always so much more fun when you slow down enough to see the small stuff, especially lichens. I’m glad to see you using the vernacular names from “Lichens of North America.” Cheers, Irwin (Ernie) Brodo

    Liked by 1 person

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