Since I recently did a post about lichens that grow on trees I thought I’d do one on lichens that grow on stone. Though there are lichens that can grow on wood or stone most of the ones I know seem to prefer one or the other. In fact the ones I know seem very fussy about where they grow, even down to the species of tree or stone. The lichen in this first photo is not that fussy though, so it will even grow on sidewalks, and that’s how the name sidewalk firedot lichen (Caloplaca feracissima) came about. Though I’ve seen it on concrete once or twice in the past I almost always see it on lime rich stones. It’s a pretty orange color and it can get quite big. This one is as big as a car tire.
Another lichen that can get quite big is the peppered rock shield lichen (Xanthoparmelia conspersa) but this example must have just gotten started because it was quite small and had few apothecia. This lichen likes to grow on stone in full sun and I find a lot of them on stone walls. They’re a good introduction to lichen study because their brown apothecia, where their spores are produced, are large and easy to see without aid.
Lichens are made up of a symbiotic relationship between fungi and algae or cyanobacteria. Technically apothecia are “fungal reproductive structures, in which the fungus reproduces itself through the production of spores” This is not the only way that lichens reproduce, but it is common and the apothecia are often beautiful and well worth watching for. The beautiful brown ones in the photo above belong to the peppered rock shield.
Some lichens are very easy to identify because there aren’t many others that look like them, and the toadskin lichen (Lasallia papulosa) is one of those. Toadskin lichens show color changes when they dry out like many other lichens. When wet it is pliable and pea green and when dry it becomes crisp and ash gray like the above example. Toadskin lichens get their common name from their many “warts.” They attach themselves to stone at a single point that looks like a belly button, and that makes them umbilicate lichens.
This is the very same toadskin lichen as the one in the previous photo. You can easily see the dramatic color change between this day when it was wet and when it was dry in the previous shot.
Rock tripe lichen (Umbilicaria mammulata) is a relative of the toadskin lichen but it doesn’t turn gray when it dries out. Instead it gets brownish and curls up. It is very pliable and rubbery when it’s moist, but once it dries out it becomes crisp like a potato chip. The Umbilicaria part of the scientific name comes from the Latin umbilicus, meaning navel. This is where another common name, navel lichen, comes from and points to how, like the toadskin lichens, they attach themselves to stone with a single attachment point that looks like a navel. It sticks itself to stone by way of this single, navel like attachment point and the rest of the lichen hangs from this central point, much like a rag hanging from a peg.
Here is what rock tripe lichens look like dry. You can see the back of it, which is black and pebble textured. Rock tripe is edible and eating it has saved the lives of people who were lost and starving in the past. Though I imagine they must taste like old rubber, these lichens were a source of emergency food for Native Americans and saved the lives of many an early settler. Even George Washington’s troops are said to have eaten rock tripe to survive the brutal winter at Valley Forge in 1777.
Rock greenshield lichens (Flavoparmelia baltimorensis.) Look like melted candle wax to me. They are very common in this area and are another of those bits of nature that you see so often they no longer register, but when you take the time to look closer you find that they are quite pretty.
If you happen to see a stone that looks like it has sprouted gray hairs you might want to take a closer look, because there’s a good chance you’re seeing a Cladonia lichen.
There are many Cladonia lichens including the well-known pixie cups, but I think these were peg lichens (Cladonia sobolescens.) Peg lichens are also a large group, with split pegs, thatched pegs, powdery pegs, etc., but these seem to fit the description of what the book Lichens of North America calls simply peg lichens. The “peg” is called a podetium and it is topped by brown apothecia.
Here is a closer look at the tiny tan / brown apothecia that sit atop the pegs. These are where the lichen’s spores are produced. They are so small that I wasn’t able to see them but luckily the camera could.
This peg lichen is a squamulose lichen, which means it is scaly, but it is also foliose, or leafy. Squamules are the small leafy, lobed growths that are at the base of the tiny peg shaped podetia. A podetium is an upright secondary thallus in Cladonia lichens. It is a hollow stalk extending from the primary thallus. Podetia can be pointed, club like, cupped, or branched in shape and may or may not contain the ascocarp, which is the fruiting body of the lichen. If the asocarp is bowl shaped it is an apothecium. In this peg lichen the podetia are not branched and the leafy squamules are rounded and grayish green to brown, with white undersides. The quality of these photos isn’t great but the various parts of this lichen are very small. I think they do show enough to make a fairly good identification but if I’m wrong I hope someone will let me know.
Scattered rock posy lichens (Rhizoplaca subdiscrepans) can be quite small and difficult to see without magnification, but it’s worth looking for them because they almost always have their bright orange apothecia showing. They like to grow on stone, especially granite, in full sun. They don’t seem to change their color when they dry out like many other lichens do. I’ve seen this pretty lichen even on mountain tops.
Here is a closer look at those pretty rock posy apothecia. The ones I’ve seen are never shiny. They always have a kind of matte finish.
Common goldspeck lichens (Candelariella vitellina) are uncommonly beautiful. Look for this bright yellow crustose lichen on stone. especially slate. I see it on older gravestones quite often. It shouldn’t come as a great surprise that, at high magnification, the body of the common goldspeck lichen looks like it’s made up of tiny golden specks. The book Lichens of North America describes the body of this lichen as “little cushions of flattened granules.” This lichen is sometimes sterile, with no fruiting bodies present, but this one had a few. Crustose lichens form crusts that tightly adhere to the substrate that they grow on and usually can’t be removed without damaging it.
The golden moonglow lichens (Dimelaena oreina) that I see are usually about an inch across but they can get much bigger. They grow in full sun on granite and don’t seem to change color when they dry out like many other lichens do. The one in the photo was producing spores and that’s something I don’t see this lichen do very often. If you spend much time in cemeteries you have probably seen this pretty lichen, because it seems to like growing on smooth, polished stone, especially granite. It is a crustose lichen, so removing it from a gravestone would be a challenge. When lichens grow on glass the acids in them can actually etch the glass and this is a problem in the big European cathedrals, especially. I would think the same would be true for polished stone.
Another lichen common to stone walls is the sulfur dust lichen (Chrysothrix chlorina.) It’s a very soft, pale yellow and hides under overhangs so it doesn’t get rained on. At least I think that’s why I always find it tucked away like this, but this is odd behavior for a lichen because they usually like a lot of rain and sunshine.
Dog lichens (Peltigera) are good example of lichens that will grow on soil, rotting wood, or stone as this one was. Dog lichens are associated with mossy areas because the mosses help provide the moisture that they need. It is very thin and pliable. It is also a foliose lichen because it is lobed, or leaf like. The upper part of the body (Thallus) is undulating or veined on this example. This lichen is large and easy to see. It is also probably quite old.
Here is another look at the dog lichen. They’re much bigger than most other lichens. I’d guess this one is about the size of a 45 RPM record, if anyone can remember those.
The underside of a dog lichen is often bright white as this one was. They also have small hairs called rhizines which help them cling to whatever they’re growing on.
Smokey eye boulder lichen is a favorite lichen of mine. The blue color seen in the above photo is caused by the way light reflects off a waxy coating on the fruiting bodies, which is very similar to the “bloom” found on plums, blueberries, and grapes. In addition to blue it can also appear black or gray depending on which direction the light happens to be coming from. The greenish-gold background color is the color of the body (thallus) of this crustose lichen. It’s a very beautiful thing and I hope you’ll take the time to look for it and all of the other beautiful lichens out there.
There is no absolute scale of size in nature, and the small may be as important, or more so than the great. ~Oliver Heaviside
Thanks for coming by.
I’ve caught up with you now, Allen, and I have enjoyed all the photos, especially these fine lichens. Winter still has a good grip in your area! We are finally experiencing winter here in my part of western Oregon, although we do not get the kind of snow I remember from back east, and nothing has lasted more than a day.
Thank you Lavinia, I appreciate the effort.
The winter here has been very strange, with most storms starting with snow and ending with sleet and freezing rain, so you probably wouldn’t recognize them.
What odd little life forms. They have an extraterrestrial vibe about them.
They’ve sent some into space and they came back and grew on like they’d never left the earth.
Fascinating as your posts always are. I’m always amazed at the extreme weather conditions that they can tolerate.
Thanks Montucky! Yes, they’ve even sent lichens into space and they’ve come back and grown like nothing happened. That’s tough!
How beautiful these lichens are! I am constantly amazed at the detailed photographs you take of them.
Thank you Clare. Sometimes I have to try several times before I get a useable shot. They’re very small!
I would love to see that Smokey Eye Boulder lichen. It is very striking.
It is a beautiful thing!
HUH, what an informative post. OUr master gardener director said it’s her favorite nature’s plant. Did you take all these pictures yourself? What a variety of lichens you have, just amazing.
Thank you yes, I did take these photos, but you need a good macro lens to do it!
As for variety, I’ve hardly scratched the surface. There are many hundreds that I don’t know.
Wow. Amazing to me
Thanks!
Wow! What a great catalog of rock lichens! A friend has a huge rock covered with Umbilicaria mammulata, which can be used to produce a beautiful purple dye on natural materials. Where my father used to live in Colorado, they would use local lichen-covered rocks for foundations, fireplaces, etc. They were generically referred to as “moss rock” and homeowners were advised to occasionally spray them with water to keep the “moss” alive. Someone out there said the different colors were partially attributed to which animal peed on them. Not sure if that’s true or not!
Thank you Pat. I’ve read about that dye and I’d like to see it on wool some day.
Lichens will live for many years without moisture but since moisture helps them keep their natural colors you father’s experience makes sense. What colorful building they must have had!
I’ve noticed that certain lichens seem drawn to where dogs and birds relieve themselves so I think itis true. Bright yellow lichens grow on the rocks along coastlines where many birds roost.
Your knowledge is extensive, your generosity in sharing is appreciated. Your beautiful photos help brighten my day. Thank you. 🙂
Thank you Ben. I don’t really know as much about lichens as I’d like to but I’m learning slowly.
Glad you liked the photos!
Always. 🙂
Wow, if there were a vocabulary test on lichen terminology right now, I’d be in serious trouble 😕. Fascinating little worlds. I especially like the beautiful symmetrical aspect of the Moonglow, which reminds me of the center of a gerbera daisy. C’mon SPRING! Interesting, as always. Thanks!
Thank you Ginny. It has taken me years to understand the little I know about these interesting bits of nature.
You’re right about the golden moonglow. It’s very symmetrical compared to most other lichens.
I like lichens and often stop to admire them on my summer walks. Thank you for giving me names and details so I’ll look at them with a more educated eye in future.
Thank you Virginia. It’s always good to know there are other lichen lovers out there!
They’re beautiful! I must make a point of looking more closely at them when I resume my walks in springtime.
Thank you Lee. You won’t have to look too hard because lichens are everywhere.
Their own little kingdoms.
Yes!
Amazing collection, and I do remember 45’s. 🙂
Thank you Judy, I wasn’t sure anyone would!
Loved the quote and all the colours, shapes and patterns of the lichens.
Thank you Susan. They’re colorful and interesting!