About SLWhite

Dabbling in many, too many, things.

Searching for Jelly Lichens

Spring is brief in Colorado, making it very important to play hooky this time of year! This post records an adventure from back in May 2009, a wetter spring than Colorado has had in recent years. That made it a perfect time to visit Lair o’ the Bear Park with a friend to see jelly lichens.  

I hadn’t visited for a while, so had to check every cliff to find the right one, way out at the west end of the creekside trail that was once the main road from Morrison to Evergreen, shortly before it enters adjacent Corwina Park.

Eventually we reached the proper cliff, where we could see not only the sought-after jelly lichens, but the wonderful Sticta, and verdant masses of spikemoss, Selaginella. The jelly lichens were soft and slimy from recent rains and lingering rivulets in the cracks and crevices of the cliff. In this photo, a large Umbilicaria (lichen, not a jelly one) is under the ring, with dark Selaginella to its right, and lighter-colored masses of true mosses surrounding.

Properly called gelatinous lichens, these lichens are so named because they lack the firm texture of more typical foliose lichens and have a characteristic translucence when wet. (They remind me of the “tree ears” we sometimes encounter in Chinese restaurant dishes, but those are actual fungi.) Gelatinous lichens are unstratified or only partially so, lacking the distinct algal layer, and sometimes the firm lower and/or upper cortex found in the “typical” lichen (if there is such a thing). The primary phycobiont species is a cyanobacterium, generally Nostoc.

They look so different when they’re dry! This one is, I believe, a species of Leptogium, with a white tomentum visible on the lower surface. Perhaps L. saturninum, but confirmation will have to await another trip. With a hand lens. For those who prefer common names, LoNA* calls this one bearded jellyskin.** (Ugh!)

By the way, you can sometimes find free-living forms of terrestrial Nostoc in Colorado (more commonly here in NY). We’ve seen them on Lyons Sandstone near Red Rocks Park.

* LoNA is Lichens of North America, the coffee table book of lichens, by Brodo, Sharnoff, and Sharnoff. Highly recommended! You can see Sharnoff’s species photos from the book at Sharnoff Lichen pages.

** Jellyskin is the name used here for the entire genus of Leptogium, as opposed to the name “jelly lichen” given only, in that book, to species of Collema, another common jelly lichen. This is the only book I know that assigns common names to lichens; few lichens have true common names.

Welcome, 2022!

Changes are afoot here at Colorado Lichens. After long dormancy, we’ve relocated and cleaned up a bit, and the transition is mostly complete as of March 17. After five years’ absence from Colorado, I don’t know that I have much more to say about the lichens of that lovely state, and will actively seek an interested party to assume this domain and perhaps some of its content.

It looks as though everything is working properly, although you may stumble across missing images. If that happens, please let me know— I’ll have a contact form up soon for reporting issues and general comments.

Iceland “moss,” Cetraria islandica

Cetraria islandica, a true lichen known as Icelandic moss, captured as an ingredient in “Icelandic schnapps.”

An unexpected encounter last week reminds me to talk about one of my favorite lichens! Cetraria islandica is not entirely rare in Colorado, but I would guess it’s rarely seen by most of us. For one thing, it occurs at higher elevations, above, say, 8000 ft. (~2440 m) It’s also cryptically colored, blending in with the forest floor, where it can be confused with other small plants, mosses, and lichens carpeting the soil.

Steeped in alcohol, "Iceland moss" becomes Icelandic schnapps—definitely an acquired taste.

Steeped in alcohol, “Iceland moss” becomes Icelandic schnapps—definitely an acquired taste.

But the lichen I encountered last week, at a friend’s house, was in a bottle, lending flavor and perhaps substance to a concoction called Icelandic schnapps. Of course, I had to taste it, and he was kind enough to oblige. Knowing he had laboriously carried it home from a visit to Iceland, I did not ask for a second glass.

Cetraria islandica is one of a few species of this genus known to occur in Colorado, although they will be more common at higher altitudes (or latitudes!). All are fruticose, after a fashion, and more or less brownish in color. (Clarity is helped here by the fact that the yellowish species are now in a separate genus: Flavocetraria.)

According to CNALH: “Cetraria ericetorum is distinguished from C. islandica … by having a consistently P- medulla, and by the pseudocyphellae being strictly marginal and sometimes indistinct or absent. Cetraria ericetorum ssp. reticulata belongs within the C. ericetorum complex comprising three mainly geographical races. Subspecies. reticulata basically comprises the subspecies occurring in North America.”

A third species, Cetraria aculeata is more truly tangled and shrubby, its branches more rounded than flattened. It was once in a separate genus, called Cornicularia.

ID Tips for Lichen Newcomers

How do you start figuring out lichens if you’re a novice, especially if you have no keys? With 85% of my books, including lichen ID materials, still in storage (long story), I’m thrown on the resources of the internet. Here are a few suggestions for exploring lichen basics (off-site links open in a new window):

Guide to British Lichens on Twigs, with picture key! Click to go to site.

Guide to British Lichens on Twigs, with picture key! Click to go to site.

There is an online lichen key from the UK for 60 British lichens on twigs (from the Natural History Museum at South Kensington); they also have a glossary of terms. To get started, choose whether the lichen is fruticose, foliose, or crustose. (See descriptions at our Shapes and Sizes page if you’re not sure.) You eventually get to a color photo of the lichen. If you get one or more results, don’t assume the species is right, but it might at least point you to a genus to check out. (I got a lot of “no results” on my searches, but I was just making up characters.)

You might try checking photos at Ways of Enlichenment, which does a good job of showing many species in each genus.

Steve Sharnoff offers some lichen basics at his website. He also has lots of photos available that may also be helpful, but this site is focused on North America. Some species, however, are widespread, and many genera are.

If you narrow it down to a few species, you can check whether they occur in your area at this database maintained by the Consortium of North American Lichen Herbaria (CNALH). Their records include specimens from all over the world. If you go to their dynamic map and click on your area (and specify a radius to search), they will generate a checklist that you can also use as an interactive key. Very nice!!

Only the lichen portal at CNALH will give you a detailed description of important characters, but at least the others provide visual references.

Note: Also posted this on iNaturalist as a journal entry.

The Latest Lichen News

Yes, we’re back, and there’s news in the world of lichens. Please forgive the long “dormancy,” of which more is explained below. But right now, things are popping in the world of lichens, and we thought we’d better attempt to update ourselves just a tad.

The Overlooked Organisms That Keep Challenging Our Assumptions About Life, at The Atlantic. As they say, “Gorgeous and weird, lichens have pushed the boundaries of our understanding of nature—and our way of studying it.” (by Ed Yong Jan 17, 2019)

[Or maybe not so “latest” after all. Here’s an earlier article about the researcher who put this idea together, Toby Spribille, also by Ed Yong, in the Atlantic in 2016.]

We’ve talked before about the fact that some lichens contain multitudes—specifically, representatives of not just two but THREE kingdoms within their symbiosis. Now, researchers are demonstrating that the situation for some lichens may be even more complex.

Hooray for lichens—the organisms that continually surprise us!

Lichen-forming fungi [all*] belong to a group called the ascomycetes. But in 2016, Spribille and his colleague Veera Tuovinen, of Uppsala University, found that the largest and most species-rich group of lichens harbored a second fungus, from a very different group called Cyphobasidium. (For simplicity, I’ll call the two fungi ascos and cyphos).

Bright green Letharia vulpina outshines pale Usnea in this photo from C. Tom Hash (https://www.inaturalist.org/users/7893, used by permission).

Bright green wolf lichen (Letharia vulpina) outshines pale Usnea (beard lichens) in this photo from C. Tom Hash (https://www.inaturalist.org/users/7893, used by permission).

Look on the bark of conifers in the Pacific Northwest, and you will quickly spot wolf lichens—tennis-ball green and highly branched, like some discarded alien nervous system. When Tuovinen looked at these under a microscope, she found a group of fungal cells that were neither ascos nor cyphos. The lichens’ DNA told a similar story: There were fungal genes that didn’t belong to either of the two expected groups. Wolf lichens, it turns out, contain yet another fungus, known as Tremella. —Ed Yong

* There are, as I understand it, a few lichen-forming Basidiomycetes as well. But for practical purposes… ascomycetes.



Tremella is commonly known to us ordinary mortals as “witches’ butter” and is a parasitic jelly fungus that seems to be fairly distinctive. I posted this photo on iNaturalist, however, and haven’t had anyone confirm its identity to date.

Tremella fungi had been reported from wolf lichens previously, but were thought to be “secondary” to the main symbiotic relationship. The “news” here is that these extra fungi may, in fact, be quite central to the concept we call lichens. At least in the genus Letharia. We’ll be staying tuned to new developments!

Yes, I’ve recently been getting active on iNaturalist (@slwhiteco), and am especially intrigued by checking out the lichens there. Unfortunately for me, lichen taxonomy has changed significantly since I studied them back in the Darkish Ages. Apparently the advent of DNA analysis has stimulated, or required, major revisions in groups, and I’m still trying to untangle the implications. Perhaps we’ll explore a few of them in a future post.

My other complicating factor is that I’m no longer in Colorado. The move, and preparations for it, were a significant distraction from this website, but we’ll hope to bring you more lichen material in the future. Sadly, other than several Cladonia and some corticolous species, I’ve not found good lichen-hunting in this part of upstate New York yet.

California gets a State Lichen!

This month, California became the first state to designate an official State Lichen. Based on the efforts of the California Lichen Society, the state legislature approved the lichen last summer and the law was signed by Governor Jerry Brown in July, but didn’t take effect until January 1, 2016.

Ramalina menziesii, lace lichen. Photo courtesy Greg Howe.

Meet Ramalina menziesii,
the Lace Lichen

finRmenziesiiAlthough one of several lichens that drape themselves in trees in long graceful strands, the Lace Lichen is distinctive and instantly recognizable. Unfortunately for the rest of us, this beautiful lichen occurs only along the west coast of North America. However, this makes it a perfect candidate for California’s state lichen: it is common along the coast and as much as 130 miles inland. No other lichen has the lacey or netted branches, although some species of Usnea or Alectoria appear similar from a distance.

Learn more about Lace Lichen and its designation at the California Lichen Society webpage. But remember, it’s a lichen, not to be confused with “Spanish moss” (which is not a moss either)!

Lichens by Haeckel 1904

Lichenes illustration by Ernst Haeckel, labeled to match the key below. Via Wikipedia, public domain.

Lichenes illustration by Ernst Haeckel, labeled to match the key below. Via Wikipedia, public domain.

Via Wikipedia, this great illustration of “Lichenes,” drawn by Ernst Haeckel to emphasize his ideas of symmetry in his Artforms of Nature, published in 1904. Click to enlarge.

Haeckel’s stylized drawings convey these lichens in their most basic forms, with much of their random meandering growth reduced to precision, as evidenced in the strict circles of #8 and #9, the ovals of #10 and #11. Despite the fact that, in the field, these are apt to appear far less uniform in shape, Haeckel has captured the “personality,” if you will, of each species, making them reasonably recognizable.

Just for fun, in the key below, we’ve linked some of the species names to a current photo from other websites for comparison. Links open in a new window; use your browser’s back button to return here.

Tafel_083_schema_300Here’s the key to these drawings, by number, with some synonymy of a more recent day added, apparently by the annotator for Wikipedia.
1. Cladonia retipora (Floerke) = Cladia retipora (Labill.) Nyl. (an Australian species, but here’s a photo from Pinterest)
2. Cladonia perfoliata (Hooker) = Cladonia perfoliata
3. Cladonia verticillata (Achard) = Cladonia cervicornis ssp. verticillata (Hoffm.) Ahti
4. Cladonia squamosa (Hoffmann) = Cladonia squamosa (Scop.) Hoffm.
5. Cladonia fimbriata (Fries) = Cladonia fimbriata (L.) Fr.
6. Cladonia cornucopiae (Fries) = Cladoniaceae sp.?
7. Sticta pulmonaria (Achard) = Lobaria pulmonaria (L.) Hoffm.
8. Parmelia stellaris (Fries) (non (L.) Ach.: preoccupied) = Physcia stellaris or Physcia aipolia (Ehrh. ex Humb.) Fürnr.
9. Parmelia olivacea (Achard) = Melanohalea olivacea (L.) Essl.
10. Parmelia caperata (Achard) = Flavoparmelia caperata (L.) Hale
11. Hagenia crinalis (Schleicher) = Anaptychia crinalis (Schleich.) Vězda

If you appreciate the elegance of nature, as Haeckel clearly did, you should look at this entire book. Browsing through the illustrations was like an instant review of invertebrate zoology and paleontology courses from college. Many of his drawings feature protozoans, medusoids, and other familiar lifeforms in those textbooks (if not in life); these would have enhanced some of those courses! Explore more at:

Kunstformen der Natur, Haeckel, Ernst, 1834-1919, Bibliographisches Institut Leipzig. Contributed to Biodiversity Heritage Library by University of Illinois Urbana Champaign.

Stereocaulon, Easy to Spot

This genus is readily recognizable, but a challenge to identify to species without a microscope or chemical tests. Stereocaulon is very unusual in structure, even for a lichen. It is generally considered a fruticose lichen, but “it’s complicated.” They have been given the common name “foam lichens,” which certainly seems fitting.

Stereocaulon sp., by Jack R. Darnell. On soil, Pike National Forest near Staunton State Park.

Stereocaulon sp., by Jack R. Darnell. On soil, Pike National Forest near Staunton State Park.

These fluffy, feathery fruticose-looking lichens actually consist of a crustose primary thallus that develops a secondary thallus of branched stalks, sometimes called pseudopodetia. In most species, the crustose part of the thallus disappears, leaving no clue that this critter is anything but fruticose.

To identify species, you also need to master a specialized vocabulary. Growing on the branches of Stereocaulon are granules or squamules called phyllocladia. The phyllocladia, whether flat or coral-shaped, contain Trebouxia, a green alga commonly found as a lichen photobiont. Nestled among them we may often find structures called cephalodia (you may recall we saw these in Peltigera as well). The cephalodia contain cyanobacteria, often Nostoc.

Closer view of Stereocaulon from previous photo by Jack R. Darnell.

Closer view of Stereocaulon from previous photo by Jack R. Darnell.

In this closer view, no apothecia are seen. I wouldn’t call this “mat-forming, without main stems,” so that kinda rules out S. rivulorum. Options (in LoNA key) for phyllocladia are “granular to squamulose, rarely coralloid” versus “warty, sometimes lobed.” What do you think? If I had to make a wild guess, I’d say Stereocaulon glareosum, which has been reported from the area.

I’d also say we need a dissecting microscope. This is why we like to talk about genera more than species! (And why we’ll maybe tackle an easier species next time!)

According to my search of collections at Lichen Portal (CNALH), in Colorado we have 15 taxa in 11 species of Stereocaulon, with some specimens not identified to species. Most of these collections are at elevations above 2400 m (8,000 ft). Our species are:

  • Stereocaulon albicans
  • Stereocaulon alpinum
  • Stereocaulon dactylophyllum
  • Stereocaulon glareosum (retains primary thallus; cephalodia brown)
  • Stereocaulon glareosum var. brachyphylloides
  • Stereocaulon incrustatum
  • Stereocaulon microscopicum
  • Stereocaulon myriocarpum
  • Stereocaulon myriocarpum var. orizabae
  • Stereocaulon paschale
  • Stereocaulon paschale var. alpinum
  • Stereocaulon rivulorum (arctic-alpine, no apothecia)
  • Stereocaulon subalbicans
  • Stereocaulon tomentosum (thallus erect, not matted; tomentose; apothecia common, brown and terminal; cephalodia blue-black)
  • Stereocaulon tomentosum var. compactum

Of the 11 species (357 specimens identified to species), most commonly collected here are S. tomentosum (129), S. glareosum (85), S. rivulorum (69), and S. alpinum (45). Chances are this specimen is one of these four. If just going by these photos, I’d love to say it’s S. rivulorum!

Stereocaulon alpinum photo at Sharnoff Photos
Stereocaulon rivulorum photo at Sharnoff Photos
Stereocaulon tomentosum photo at Sharnoff Photos

Data summarized from:
Consortium of North American Lichen Herbaria (CNALH). 2014. http//:lichenportal.org/portal/index.php. Accessed on December 27.

Lichens and Rocks

saxicol0090Lichens that grow on rocks are called saxicolous, and a great many species fall into this category. These are the bright splashes we see when out hiking or just enjoying the scenery. But did you know that some of them have distinct preferences in the types of rocks they grow on? Their occurrence is not haphazard; they need to find the correct substrate, and knowing the preference for a particular species can help you locate it!

Substrate Specificity

The preference of lichens for a particular rock type can be based on chemistry: is the rock basic or acidic? Limestones, which are relatively sparse in our area, often support lichens that may not be seen elsewhere. Other species will be found on sandstones or the granitic or metamorphic rocks of our mountain areas. The cement of sandstones can be either calcareous (basic) or siliceous (acidic), which determines which lichens it will support.

For example, Xanthoparmelia species will generally be found on siliceous rock types, and thus are common in the granitic or metamorphic substrates so abundant in the Rocky Mountains and other places where igneous or metamorphic rocks dominate.

Bright orange Xanthoria elegans responds to environments high in nitrogen, and can often be seen in broad swaths below bird or rodent perches.

Bright orange Xanthoria (probably X. elegans) grows in channels where nutrients are washed down from animal perches. Fountain Sandstone, S.L. White.

Bright orange Xanthoria (probably X. elegans) grows in channels where nutrients are washed down from animal perches. Fountain Sandstone, S.L. White.

The same species seem to occupy both cement and granitic stone in this wall. S.L. White.

The same species seem to occupy both cement and granitic stone in this wall. S.L. White.

Lecanora muralis, a cosmopolitan species across the U.S., occurs on various rock types, also likes nitrogen, and often colonizes cement and mortar because of their high calcareous content. Because it appears on manmade surfaces, it has been called “stonewall” lichen (in fact, muralis is Latin for “of the wall.”) On the stone wall in my backyard, however, it appears equally happy on the granite cobbles as on the adjacent cement.

Lichens and Weathering

On this boulder of Fountain Sandstone, lichens are assisting in the weathering of the rock by exfoliation, or spalling. Photo by S.L. White.

On this boulder of Fountain Sandstone, lichens are assisting in the weathering of the rock by exfoliation, or spalling. Photo by S.L. White.

Lichens also help break down rock, as we learned when we were young. Their chemical and physical interaction with the substrate on which they grow can be significant. Crustose lichens, in particular, closely interact with their substrate and are so abundant they play a significant role in weathering processes.

Direct penetration of rhizines, in the case of foliose lichens, or medullary hyphae in crustose lichens may physically fracture rock surfaces. Once imbedded within a rock, expansion and contraction of lichen thalli with changes in temperature and hydration status will contribute to the pressures that result in surface disintegration of rocks.  —Nash et al., page 153

Umbilicaria, or Rock Tripe

Umbame1882Umbilicaria americana, FROSTED ROCK TRIPE
This species and its relatives are known as “rock tripe” and said to be edible, though perhaps only in dire situations. For example, the related species Umbilicaria mammulata reportedly fed George Washington and his starving troops during the harsh winter of 1777 at Valley Forge. A distinctive and abundant lichen on moist, vertical cliff faces in the Front Range, it lacks apothecia and has a sooty black underside covered with rhizines, creating a velvety appearance.

umbil2346smThalli are leathery (and green!) when wet, and are “umbilicate” (attached only at one central point); they can be 15 cm across. Largest and most notable of our umbilicate species, this often grows in huge colonies.

Another large species of Umbilicaria, this brownish one with abundant black apothecia and a more wrinkled upper cortex. Perhaps U. hyperborea.

Fun fact: Some species of Umbilicaria have intriguing black “gyrose” apothecia with concentric fissures. This species, however, is rarely seen with apothecia.

Don’t be fooled: Umbilicaria vellea is similar, but usually smaller and generally found at higher elevations or latitudes. Details of the rhizines distinguish the two.

A monotypic colony of Umbilicaria on metamorphic rock cliffs in Bear Creek Canyon, Jefferson Co., Colorado.

A monotypic colony of Umbilicaria on metamorphic rock cliffs in Bear Creek Canyon, Jefferson Co., Colorado.