Paul Nordberg
My activities & loves
Paul Nordberg
My activities & loves
The records and illustrations here cover some of the more common lichens of Ipswich and the surrounding North Shore of Massachusetts. The list does not pretend to be comprehensive or authoritative. Rather, it reflects the ongoing efforts of an amateur to learn about an intriguing form of life, pervasive but very different from our own.
I continually revise earlier entries as I discover the need for corrections and clarifications. I am sure that I will uncover further needs as my knowledge grows.
I welcome comments and questions.
Rock whitewash lichen (Phlyctis petraea) was first provisionally named in 2005 and formally delimited in 2017, though it has been collected and studied for a century by now. The introduction to the key study is worth quoting:
Sterile crusts still present a taxonomic quandary as they frequently lack, and in some cases never possess, many of the common diagnostic characters present in sexually reproducing lichens ( e.g., ascospores and apothecia). Historically, familial and generic placement was limited to finding a rare sexually reproducing individual, or informed by gross morphology, chemistry, photobiont type, distribution, or habitat.
P. petraea is often found "in dark, moist overhangs" of stone, as is the case with the specimen pictured here. The description in the paper, "rimose with conspicuous schizidia (Fig. 4C)," is quite technical but directly on target. I certainly have learned that lichens that look like blotches of white paint on boulders are far from easy, as the article notes, but feel that this identification is a reasonable one. I spent some time going over the details, including Figure 4C, learning in the process.
I will make a tentative identification of this specimen as whitewash lichen (Phylictis argena), pending results of chemical testing. Its morphology, substrate and frequency are a very good match for authoritative technical descriptions and images, but I want to be careful since there are so many similar-looking white lichens.
Wikipedia notes, "Phlyctis argena has a thin crustose thallus that is white, greyish or green-grey in colour. The identification can be confirmed with the spot test application a drop of potassium hydroxide (K-test) to the thallus, which will turn yellow and then red."
I am learning: first, that it is useful to go beyond my initial short list of the most common lichens in this area; and second, that an inexpensive container of KOH would help me answer specific questions, not just be a piece of lichenology paraphrenalia that I wouldn't actually use.
Beard lichens are one of the first varieties many people may pay attention to, including me. If they're not warm and fuzzy, they're at least fuzzy.
The specimens here are growing on the bark of a young linden tree, a cultivar planted at Appleton Farms. Like their host, the these growths are young and small. There are other lichens in the picture as well.
I have found this group of species confusing and have changed my mind a few times about which thing is which, and I may again. My current best belief is that this specimen is Usnea mutabilis, commonly called bloody beard lichen.
Wikipedia reports that U. mutabilis "is a grayish-yellowish pale green, unequally branching, shrubby… commonly anchored on holdfasts on trees, mostly in eastern North America … The thick axis and medulla are dull red." You can see red tints in the microscopic enlargement of a bit of the growth.
The stalkless cladonia – or stalkless cup – lichen (Cladonia apodocarpa) looks much like several other members of its genus, including the common powderhorn lichen – but without the powderhorns. The second part of its scientific name is formed after the Greek άποδος (footless) + καρπός (wrist). Its bodies are small, looking at a casual glance something like a fuzz or powder. But on closer look, they are of leaflike ("foliose") form, not flat ("crustose").
Perhaps because it is so unassuming, the name of C. apodocarpa does not appear on some local lists that I use. It is, however, quite common. This taxon is unusual among the Cladonia in colonizing hard stone.
The appearance of this specimen is a good visual match for the common button lichen (Buellia erubescens). As the English name indicates, B. erubescens is common and reliably recorded as present in the Town of Hamilton, less than a mile away.
Unfortunately, I was careless in my record-keeping and my photographs do not resolve the key question of what this sample was growing on. My recollection is that it was on an ancient beech, but I am not sure of that. Also, given the number of look-alike species, it would be appropriate to test it with potassium hydroxide. (This would be like a good occasion for me to splurge and purchase a container. It's inexpensive.) Pending results from these follow-up tasks, I will call this identification reasonable but tentative.
The Consortium of Lichen Herbaria notes, "Xanthoria candelaria [now redirected to Polycauliona candelaria] is a very variable taxon occurring on a wide variety of substrates, and it is in need of taxonomic revision throughout its distribution area." The specimen shown here clearly fits into the range of phenotypes shown by COLH.
In autobiographical mode, I will note that my lichenology skills are slowly but definitely improving. I was readily able to recognize this smallish orange growth on the edge of Appleton Farms as something that I had not looked at before, and in followup to identify its classifiation with modest effort. Unfortunately, the autofocus mode of my recently acquired pocket camera is unable to cope with closeups in bright sunlight, and manual focus is impractical because the viewfinder image is not visible in that situation. Fortunately, I had managed to secure a sample of this colony and brought it home, where I was able to take pictures including the one you see here, using the same camera.
Rough speckled shield lichen (Punctelia rudecta) is a medium-size lichen with leaf-like lobes. It is common on trees and mossy stones in this area. The individual lobes are about the size a finger-tip, but join each other in clusters that may be of some size.
The shapes seem like much smaller versions of common shield lichens. Especially at the beginning of this pursuit, I would often look at a small growth and wonder, is this a baby state of something I already know, or something else entirely? I am slowly getting better at figuring it out. The lichen texts I have found, curiously, are silent on early and end of life phases.
There is much that's unsettled and unclear about the genus Lepraria, commonly called dust lichens, and similar species. Their members are very small and do not reproduce sexually, leaving them unamenable to common approaches of lichenologists. It's not even agreed whether key taxa are present in North America.
After spending a while looking at the situation, I am withdrawing a previous post, at least for the time being, not necessarily because it was wrong, but because it does not reflect a current consensus. That consensus does not exist. This was about the zoned dust lichen, L. neglecta. I have left in place the post for Fink's dust lichen, L. finkii, which seems a key and fit placeholder about its topic until the dust settles, so to speak.
This brings us to Lepraria incana. On the one hand, the Council of Lichen Herbaria, whose lead I generally follow, is silent on the topic. Fools rush in where angels fear to tread! On the other hand, there is an highly common and widespread powdery white lichen that had been known, at least until recently, as L. incana, the last part of the name meaning "hoary" or "gray."
So, I am including L. incana because it at least gives a presence to an extemely common lichen, whatever its future name(s).
Chrysothrix candelaris is one of the genus of gold dust lichens. The appearance matches the name. This image tends more toward the green than the small sample I brought home with me. I could "correct" the picture by shifting it to a more yellow color balance, but I am careful to avoid such practices. (I have made the image a bit brighter, which seems reasonable because the growth was in rather deep shade.)
This specimen is at the Bald Hill Conservation Area in Boxford. I have not found specific records of this taxon in Essex County, but it is widespread throughout the region.
Pertusaria pustulata is not as common as dandelions or crabgrass, but it does have a documented presence in Essex County in a habitat like the one where I found this specimen. Its appearance closely matches authoritative illustrations for this taxon.
I am not 100% sure about this call. I am leaning toward adding a small bottle of postassium hydroxide to my test chemicals, now limited to household bleach. That would cost me $16.95 plus sales tax. It would not definitively resolve this question, or others, but it could provide corroborative evidence for, or nearly conclusive evidence against, this particular identification. – Such things start to make more sense as I learn more and am able to identify specific questions and distinctions.
Leimonis erratica, even more than most lichens, is variable in its appearance. Here, there are concentric whorls of black bodies in an eye-catching pattern, with a background in some places greenish tan, in other smoky in hue.
Olive Cladonia (Cladonia strepsilis) has shapes like the lumpy sponges from the sea once commonly used in household cleaning, but smaller.
Since lichens grow very slowly – people often cite the figure of 1 mm per year, though of course there is great variability – usually they make their homes on things that are going to be around for a while, such as large stones and trees. Many members of the Cladonia family are exceptions to this rule, taking as their habitat soil and decaying organic material. They certainly have figured out how to thrive in their niche.
The first thing that caught my eye at the Tompson Street Reservation was the bushy – "fruticose" in the language of lichenologists – growths on the very large granite boulders at the entry. I am used to seeing this growth form on trees and twigs, and on the ground in "reindeer" lichens, but had never before seen it directly and firmly attached ("umbilicate") to stone.
I believe that it is Ramalina intermedia. On the one hand, there is no documentation of the presence of this species closer than Weston, 35 miles away. On the other, there is no other rock-dwelling ("saxicolous") lichen of similar character in local records that I can find, and the morphology of this specimen corresponds closely with that of R. intermedia.
Very exciting!
Mealy rim lichen (Lecanora strobilina) is variable in its color. In the image shown here, it is yellow-green, with the centers of its discs the same. The growth you see is next to a version of the what seems exactly the same, except colored light gray. Because there seems to be some kind of mixed area of transition, I am guessing that it is one thing of different hues rather than two demonstrably different things. But I am not sure, so I will not show the light gray version here.
This specimen comes from a shaded hill on the Tompson Street Reservation.
Plated rock tripe lichen (Umbilicaria muhlenbergii) is notable for it shaggy edges, frequent perforations, and black spots. These features distinguish it from smooth rock tripe and the common toadskin lichen.
These growths were near the entry to Tompson Street Reservation of Gloucester. The small parking area near the kiosk there is surrounded by a riot of stone-dwelling lichens of all sorts, climbing and crawling over each other toward the sunlight.
Wikipedia notes, "Cladonia boryi, also commonly known as fishnet cladonia or fishnet lichen, is a species of lichen. It is distinctive in the genus Cladonia because the stalks (podetia) are very wide, seemingly hollow, and often perforated, hence the colloquial name - the fishnet lichen. It is also known as Bory's cup lichen." Evidently it was named after the botanist who first identified it, Jean-Baptiste Bory de Saint-Vincent.
The substrate of this one, bits of leaf mould and moss amid castoffs in an old granite quarry, is a bit unusual. It closely resembles the reindeer lichens of Crane Beach in Ipswich.
Physcia adscendens is easy to pass by, given its small size and inconspicuous color. On top of that, it closely resembles its near cousin P. tenella.
The British Lichen Society notes, "Physcia adscendens is similar but has lobes which are hooded and burst to expose an internal mass of cream coloured soredia." The Council of Lichen Herbaria comments, "The species is easy to recognize by the cilia on the lobe margin and the helmet shaped soralia." So far, so good… except then COLH continues, "Physcia adscendens differs from P. tenellula in several aspects. The latter is much smaller and has a different type of soralia and hairs on the upper surface."
So far so good, mostly, except the part about size isn't quite fitting my experience and other traits reported here. Well, the life of an amateur lichenologist is not always easy, and the paths are not always straight or well-marked. I will keep my eyes open for other specimens on wood, which is reported to be the favored habitat of P. adscendens.
I am generally hesitant with flat, dark, colorless lichens, but I am reasonably happy with the identification of this specimen as Rhizocarpon grande. There is a related species, R. disporum, which looks very similar but lacks a strong record of presence in this area.
Like the references, this observation has a black/gray/white warty body with a black margin. The species is clearly present in its area. The rock it is growing on is evidently siliceous – a fancy word for "silicon-based" – as is apparent from its hard, rough surface, unworn by millenia of weathering.
I am hopeful that I have added a new possibility to my range of routine options for lichens of this general character.
The highest of the eponymous granite blocks of The Monoliths reservation must have at least a dozen different kinds of lichens growing over them.
This small growth of Rhizoplaca subdiscrepans caught my eye first because its pale orange color stood out from the surrounding grays, and then because its subunits form an unusual crowded pattern.
Cladonia furcata is occasionally called "many-forked cup lichen" – furcata is Latin for "forked" – and is sometimes spoken of as a "False Reindeermoss." It does resemble the "true" reindeer lichens and is in fact their cousin.
The specimen here is a more shy and smaller version of the reindeer lichen that spreads exuberantly in the sunshine of untold acres of sand dunes at Crane Beach. C. furcata most often makes its home in a cluster of moss, and so tends toward shady areas. I've noticed that the Cladonia of the sand dunes are often near moss. It is clear that this taxon is present among the other varieties there, but I want to go over things again before I say that there are four kinds of "reindeer" lichen in that location.
A park in Manchester-by-the-Sea, formerly Agassiz Rock, is now known as The Monoliths. The new name is apt for the awe-inspiring size both of the granite boulders there, and of the growths on and around them. If smooth rock tripe lichen (Umbilicaria mammulata) grows a millimeter a year, many of the examples must be close to a century old, like the trees above them.
I have found many questions and views about whether humans can eat smooth rock tripe. When times have been hard, sometimes people have, and a few still do (after boiling it to remove the bitter taste). As far as I can learn, it is not harmful but of doubtful nutritional value, and not particularly tasty.
According to the British Lichen Society, the fringed rosette lichen (Physcia tenella) is "common on trees and twigs but rare on stonework/rocks except where overhung by tree branches." That was the situation of this specimen in the Hamilton Cemetery. I suspect its growth was facilitated by mosses and other lichens that have built up deposits of organic material on the headstone.
This lichen is notable for the presence of hair-like growths on the ends of its lobes, a trait it shares with the near look-alike P. adscendens. There are a handful of reliable reports of its presence in Essex County.
In a visit to the Hamiliton Cemetery yesterday, an overcast afternoon following twelve hours of rain, I was immediately struck by the reddish cast of lichenous growth on the surface of some of the tombstones. As I wandered about, I gradually realized and confirmed that the color occurred only on the limestone headstones, never on the granite or slate markers. It was the mealy firedot lichen (Flavoplaca citrina, earlier Caloplaca citrina), I established after some confusion in follow-up research.
Remarks on Wikipedia are spot-on:
Flavoplaca citrina, the mealy firedot lichen, is a species of saxicolous (rock-dwelling), crustose [thin] lichen … It is a common species…
Throughout its taxonomic history, the species has accumulated numerous synonyms due to multiple redescriptions and reclassifications, including various designations as varieties or forms of other species.
Flavoplaca citrina is commonly found on calcareous (chalky) or nutrient-rich substrates, such as limestone, concrete, mortar, bone, and asbestos cement. It especially thrives on walls in sunny locations…
(I realize now that a puzzling orange growth on a fire hydrant close to me is F. citrina. Iron oxide tends toward the alkaline, matching the nature of the calcium oxide of limestone.)
Expert consensus seems to be that what is called Verrucaria nigrescens in fact an umbrella term that includes a number of undefined groups of organisms. That said, the specimen here seems to fit somewhere in the picture.
The Consortium of Lichen Herbaria comments, "Many samples filed under that name belong to other species or are not clarified yet." The website Marine, maritime, oceanic and similar lichens notes, "Verrucaria nigrescens s.l. is highly variable and probably encompasses several taxa."
There is consensus that the range of V. nigrescens is wide. Perhaps because there is little certainty about what the lichen is, there is even less certainty about where its range begins and ends. – For the present, to my eye the range includes Newbury and other towns of Essex County.
Having learned that what I was considering as one, was actually at least two species of reindeer lichen logically raised the question: more than two?
Yes.
Star-tipped reindeer lichen (Cladonia stellaris) is of a much more gray hue than the others I noted earlier. This is not a matter like changing color of hair in aging humans, as I had naively told myself, but a sign that we have distinct varieties of things from their start.
A microscopic close-up reveals that the tips of the specimen are star-shaped, as the common and scientific names both indicate. The one shadow of doubt I am left with is that the points are of a dark color, which I don't find mentioned in the literature.
More than three kinds?
I noted earlier that both Lecanora pulicaris and L. hypocarpa are documented as present in this area, but that experts advise that they cannot be told apart outside of the laboratory.
That said, I will note that the specimen shown here is different in habitat and appearance from those associated with the earlier observation for L. pulicaris. The locations are some six miles apart. The one here is in densely shaded wood, the early observation in an open, sunny location. This observation is not close to others like it, the other is in the middle of almost universally colonized trees. This one is on a mature tree with rough bark, the others on younger trees with smooth surfaces. This one has a greenish tint and is heavily populated with tiny reproductive disks, the others more white and less densely covered – but with markedly larger discs. This one is roundish with irregular edges, the others nearly always form well-differentiated bands.
Perhaps the two are part of the same taxon, perhaps not. It is worth bearing in mind that traditional definitions of species may be trying to put a round peg in a square hole in this situation.
At any rate, this specimen is much like one shown in the Consortium of Lichen Herbaria portal for L. hybocarpa, also on a fallen tree.
Brown cobblestone lichen (Acarospora fuscata) is one of the better-behaved lichens I have studied. It is brown (mostly, sometimes running quite dark or light), looks rather like small cobblestones, and is a single recognized species rather than a mire of confusion and hotbed of controversy.
And it mingles and gets along well with all kinds of other lichens, as is shown in the image here, from the Burying Ground of the First Settlers in Newbury.
I find identifying white (or black) lichens on rock challenging. If the color of lichens is highly variable, at least having some color offers a clue. Stones of any size are usually not clean or easy to lug home for closer study, and the growths on them most often are fixed tightly to the surface, like paint, without any obvious display of reproductive bodies. Altogether, there's not much to work with.
I believe that this sample is mostly likely Trapelia placodioides.
On the one hand, there is not broad documentation of the presence of the species in this area, and its firm identification requires professional analysis.
On the other hand, T. placodioides clearly does have a world-wide distribution, with two or three credible reports of its presence around my area. Lichens of North America comments, "It is a fairly common, shade-tolerant lichen on forest boulders in the Northeast," which exactly fits the location of this sample. Its appearance matches neatly with a description, reported habitat and images from Leicestershire, farther away.
I very deliberately decided against setting up lab facilities at the outset of this pursuit, but I read that this species presents a red color with the standard calcium test – using ordinary household bleach. I managed to come by a small dropper bottle and put a couple of spoonsful of bleach into it. On a return visit to the site, I found that spot tests of growths like it readily and consistently produced red stains. (One might have guessed that bleach would remove red colorations!)
All in all, it seems like a reasonable fit to me.
This lichen certainly merits its characterization as "tiny button." Amandinea punctata is also called Buellia punctata. Its appearance is characterized by the dark spots of its reproductive disks on a light, often cracked background.
The Consortium of Lichen Herbaria notes observe that studies "suggest that corticolous [bark] material in North America may belong to more than one taxon… The identity of the type of B. punctata is currently not resolved."
The presence of the species in this area is well-documented, whatever it is (or they are).
Common toadskin lichen (Umbilicaria papulosa, in older records Lasallia papulosa or Gyrophora papulosa) is dense throughout the Bow Ridge Conservation Area of Lynnfield. This area is hilly, thick with granite. It was formerly the site of the Kallenberg Quarry. The lichen is frequent throughout this site and neighboring Saugus Quarry area.
A smaller growth of another, unidentified species is also present in the picture shown here.
I walked by and glanced at this lichen on my patio many times in the past few months without taking a very close look. Mortar rim lichen (Myriolecis dispersa, earlier Lecanora dispersa) is tiny. The discs (reproductive bodies) shown in the image are a few tenths of a millimeter in diameter.
As Lichens of North America notes, the "thallus [body is] usually growing between the rock crystals and absent from view." On casual observation, this colony seemed only one of a series of dark, dirty smudges. The stone itself is slate, covered with some kind of protective coating associated with commercial use. I don't know what the coating is, but lichens seem to like it, since a variety have settled on it. It is in full sun.
The lichen shown here is evidently of the genus Lepraria. There are a number of closely related species within that genus, with uncertain distinctions. At a venture, I am calling it Fink's dust lichen (sometimes named "fluffy dust," Lepraria finkii). On the one hand, there are not recorded occurrences of the species in this immediate area. On the other hand, there is documentation of close cousins within the area, and the appearance of this specimen is closest to that of L. finkii. It is growing on a fallen pine, a favored habitat for its close family. A few inches away were growths of another species favoring that habitat, lipstick powderhorn lichen (Cladonia macilenta).
By appearance, this specimen could fit either as common powderhorn lichen (Cladonia coniocraea) or as smooth-footed powderhorn (C. ochrocholora). The distinction between the two species is apparently confused; the Consortium of Lichen Herbaria (COLH) notes, "The nomenclatural status of the names C. coniocraea and C. ochrochlora is open."
I will list it as "common" just because it is that, and my policy is to steer in that direction. One could argue for the alternative because the COLH description does not include stone in its recognized substrata for C. coniocraea, while for C. ochrocholora it reports, "also on moss covered rocks, particularly at damp sites," which is precisely the situation here – but it immediately adds, "see discussion under C. conicraea."
There are bits of another, lighter-colored lichen at the top of the image here.
This growth of peppered rock-shield (Xanthoparmelia conspersa) readily established itself on a granite step at my home, placed twenty years ago. It was not at all fazed by the heavy soot left from the coal-burning age. While the species has large variations in appearance, this one matches well with published images.
I have observed specimens like the one shown in a number of places. This one is from the Hunsley Hills Conservation Area in Rowley. The growths in the picture are visibly wet from early morning mist. The dark area of the specimen discussed here is growing over another light-colored lichen, possibly of the smokey-eyed boulder variety, with bits of moss around.
After considering a number of possibilities and changing my mind, I believe that the most likely scenario is that it is smooth map lichen (Rhizocarpon hochstetteri). It is also possible that it is dusky map lichen (R. obscuratum). Appearance, notably of the dark rim, supports the former. Previous reports mostly support the latter. There is recognized confusion and debate about these species among experts.
I had earlier reported it to be Leimonis erratica, which is not impossible but seemingly unlikely.
Mapledust lichen (Verseghya thysanophora) has a light green body over a white underbody. As its name suggests and is the case here, it often grows on maple bark, but is found on other trees as well.
"It is a common lichen in eastern North America," an article in The Bryologist reports. It is cited less often than some other species in my usual sources for this area, but has been reliably reported along the Ipswich River and in Boxford, both only a few miles away.
Reindeer lichen (Cladonia rangiferina, sometimes incorrectly called "reindeer moss") is broadly known in this area and in others. Here, it is spread over vast areas of the dunes surrounding Crane Beach, being one of the few organisms that can thrive in the nutrient-poor sand and salt spray.
Yes, reindeer do eat it, in places where there are reindeer. (And yes, humans can eat it, but it requires a while to prepare.) There is quite a bit of interesting natural history for those who are interested in such things; a Google search will turn up an amazing number of narratives.
It took me a long time to realize that what I was glibly considering "reindeer lichen" actually includes at least two distinct species. The picture above shows the two growing side by side. The image is the same as for Dixie reindeer (C. subtenuis), below, but cropped to focus here on C. rangifera, on the right.
"Dixie reindeer" is a curious name. I can't figure out where it came from. Perhaps it is tongue-in-cheek? I note that the species (the lichen, not the reindeer) is common in North Carolina.
In any event, Cladonia subtenuis looks much like its cousin, C. rangifera, the "true" reindeer lichen of Arctic regions. On close inspection, the branching of the former is much more intricate than that of the latter, and the color is more grayish green, less yellow-green.
In my area, the two grow side by side, as in the image above. Here, it is cropped to focus on C. subtenuis, on the left.
I found patches like these on the same tree, a few inches from each other. Their morphology is very similar, even on magnification, but with different colors: light gray and yellow-green. There was no shade in between or piebald specimen. This raises questions that are unlikely to be resolved definitively without detailed laboratory study.
My best guess at this point is that both are fused rim lichen (Lecanora symmicta). These were growing close to the Ipswich River, a location where the species has been reported before.
Lichens often change color when they are wet, as the underlying green of the algae shows more through their thin fungal coat. After a recent rainy spell, I noticed some patches of unfamiliar lime green in a very familiar expanse of pale green and gray growths. Looking more closely, I found cups of light brown, with whitish rims. The well-known adjacent species do not have such structures.
There are many views on the classification of bottlebrush shield lichen (Parmelia squarrosa), and any number of look-alike species. P. squarrosa is very common and widespread, with reliable documentation of its presence in this area. The specimen shown here has size, morphology, color and habitat matching those documented for P. squarrosa. The light brown discs in particular fit well. Basic microscopic comparison has been corroborative as well.
I am relaxing my practice somewhat, naming this species even though it is not documented as present in the immediate area where I found it, according to a couple of the references I normally use as guidance. Partly, this is a matter of many other reports up and down the coast of Massachusetts and inland. Partly, my inclusion reflects my growing comfort with lichen anatomy and its special language. Partly, credit is due to a wonderful pen-and-ink illustration that accompanies the careful description I relied on.
I found this specimen of Parmeliopsis hyperopta on the bark of a pine tree, a favored habitat, in Bradley Palmer State Park.
The pedigree of this species and its territory and kin have been under discussion for over a century. It has a cousin, P. ambigua, whose name is an apt commentary on the situation.
I will tentatively identify this specimen as orange-cored shadow lichen (Phaeophyscia rubropulchra) on the basis of gross morphology and of couple of credible citations of its presence locally. Curiously, this growth and a few of the published images of the proposed species show dark areas surrounding the lichen.
That evidence is less than desirable, to be sure. In particular, it would be due diligence to verify the orange-red interior of its medulla. That is more easily said than done, especially in the case of a growth on stone, which makes it hard to break off a reasonable sample to take away for closer study. Perhaps another day I will return and find a way to prise off a fingernail-sized piece from a low-visibility location.
Roger Tory Peterson's seminal Field Guide to the Birds did not include the pigeon. That obviously wasn't an oversight. I don't know if he had an active dislike of pigeons, or simply felt there was no call to discuss such common and banal creatures. Or perhaps he was a purist; early American settlers brought the first pigeons from Europe.
My omission here of rock greenshield lichen was simply a matter of neglect. I will rectify that now. Rock greenshield lichen (Flavoparmelia baltimorensis) is as common as pigeons are. It generally was and often still is lumped together with common greenshield lichens. Experts now distinguish the two. One grows on rocks, the other on trees.
In shadier, damper locations the color tends to run more toward a yellowish green.
The Burying Ground of the First Settlers in Newbury, Massachusetts dates back to 1638. Although the earliest burials generally lacked headstones, the field has an amazing profusion of lichens, growing around and through and on top of each other, over the memorials that remain.
The one shown here, Star rosette lichen (Physcia stellaris), is common throughout this area of the country.
I looked around the burial area at the rough fencing and other unworked stone but found almost no lichen growth. This echoes my experience at the few other cemeteries I have visited. The pattern leaves me wondering if there is something about the human process of working the rock that creates microscopic fissures that facilitate the attachment of the lichens, or perhaps removes a coating of something that deters them.
Monk's-hood lichen (Hypogymnia physodes) is common in this area.
Because it is light gray, its presence is unobtrusive amid the vast spread of common greenshield lichen. It took me a long time to recognize the distinction. The overall sizes and shapes of the lobes are quite different, though, once you stop to look at them. The ability to enlarge images proves to be vey helpful in this field of study.
Unlike some other labels here, the name of the Common script lichen (Graphis scripta) is easily understood, since it (1) is widespread, (2) has lines that look like some foreign handwriting, possibly from some exotic ancient culture, and (3) is a lichen. "Common script lichen" may be a conflation of a few species.
"Powder-tipped shadow lichen?" – Whoever thinks up the common names for lichens is as fanciful as the branding department of an interior paint manufacturer or the marketing division of a dietary supplement maker. The scientific name Phaeophyscia adiastola is unapproachable, even for those who, like me, studied Latin and Greek for years.
Whatever you call it, its pale green color fits unobtrusively into the vast scatter of common greenshield lichen around it. I passed by it countless times until yesterday I first noticed the clusters of rimmed dark disks.
Lipstick powderhorn lichen (Cladonia macilenta) has red caps on its stalks, like its cousin British soldier lichen. These are very small, only a few mm high, so one needs to look very closely to see the tips.
The species has the confusing preference of growing on dead wood, as it is here. That is a very unlichen-like proclivity. Mosses and fungi need organic matter to feed on, but lichens provide for themselves in this regard. It took me quite a while to pick out this group, though I pass it nearly every day.
The name "smokey-eye" is curious, because this lichen has striking discs of blue – "eyes" – on a smokey background. Well, some might say the discs were bluish-gray with dark rims. (I recommend enlarging the thumbnail image shown here.)
P. albocaerulescens is a common lichen. I found this example along the Ipswich River, where it has been reported before.
I found this sulfur dust lichen (Chrysothrix chlorina) close to the Ipswich River. It has been reported before along that river, and pictures of it are common enough that I recognized it immediately when I saw it.
In moist and shady locations, its color can be quite green.
"A very common lichen, Physcia millegrana has been described as the most pollution-tolerant macrolichen in eastern North America."
Here, it is widespread over a variety of stones across the Old South Cemetery, which dates from the Colonial era.
It is possible that the species is not P. millegrana, which is generally reported to grow on trees, but one of its close cousins.
Wikipedia notes, "Members of the [Lecanora lichen] genus have roughly circular fruiting discs (apothecia) with rims."
If you enlarge the image shown here from its thumbnail size, you will see that the disks have reddish brown cores. The picture matches closely with one by Stephen Sarnoff, included in the listing by the Consortium of Lichen Herbaria. Other specimens have areas with similar dark reddish brown cores, next to areas where the cores have only faint tinges of coloration.
Similar bands are pervasive in this area. Nearly all young and other smooth-barked trees have tiger coats with stripes from white to light gray. Most often, dark discs aren't evident on the growths, but that is only what one would expect in a reproductive phase. (What proportion of the humans of the planet are visibly pregnant at any given moment?) At this time, my impression is that all of these are variants of a single species. However, I will continue to explore other possibilities. The genus has many species very similar to each other. Lecanora hybocarpa, bumpy rim lichen, is also common in this area, and not distinguishable from L. pulicaris without chemical tests.
Pixie cup lichen (Cladonia pyxidata) is tiny. The "cups" in the picture could not hold as much as a drop of water apiece.
I must confess that not long ago I collected another sample but discarded it, thinking, This is a moss, not a lichen. I am learning, little by little!
In the specimen shown here, the cupped stalks of the apothecia – reproductive bodies – are about 3 mm high. It came from a shaded, low-lying and silted area of sand dunes. The particles in the lower part of the image are grains of sand. Not far away, other examples are growing up the bottoms of pines.
Moonglow lichen (sometimes "Golden moonglow") (Dimelaena oreina) grows "on steeply inclined surfaces of hard siliceous rocks", the Consort of Lichen Herbaria reports. Another source notes that it occurs "on rocks and tombstones in exposed areas." It is common hereabouts.
In a new and confusing area of study, I have found this example to follow the script exactly and look just like the pictures in the books.
The name moonglow is evidently derived from the radiating appearance, called "areolate" and "radiate-plicate" in the language of lichenology. The form reminds me a bit more of the rays and halos shown in old paintings around the heads of holy persons and angels.
The cinder lichen (Aspicilia cinerea) is aptly named.
In the image here, the large gray shapes are cinder lichen, with smaller moonglow lichens and perhaps bits of coal dust lichen around them.
After some head-scratching, I will report a couple of specimens on slate as seemingly belonging to this genus, if not species. Both of the slate-based growths are surrounded by striking halos of olive green, which possibly fits with some some printed references but no images that I can find. In the example shown here, there are bits of other lichens scattered around.
One possibility is that the green comes from some interaction between the lichen and the chlorite-containing slate. Wikipedia notes,
The name chlorite is from the Greek chloros (χλωρός), meaning "green", in reference to its color.
There are various technical tests that could be made, beginning with simple chemical assays. I am holding off on moving to that level, however. I am feeling like a beginning bird-watcher who has learned to tell a crow from a robin from a turkey, but doubts that that his abilities are quite up to a top-line set of binoculars. More likely, a firmer grasp of lichen anatomy would be the best next step.
"Coal dust lichen" is a common term for a common lichen, aptly named. Beyond that, there is considerable variation and evolution in the story.
Acarospora privigna is also called Polysporina simplex. The Consortium of Lichen Herbaria reports that it is found "on acidic [i.e. siliceous] or carbonaceous rocks, in sunny, open sites." Lichens of North America reports that "Polysporina urceolata is a related species on limestone." That is a neat fit for the substrate shown here, but I have not been able to find a geographical range described for urceolata. Simplex is widely reported to be found in this area.
Though its bushy appearance resembles that of Usnea subfloridana, noted below, this lichen caught my eye with its differing texture and tree-trunk location – I have only seen the former on twigs. Initially, my impression was that it was Usnea hirta. After microscopic examination and further research, I believe now that it is more likely Boreal oakmoss lichen (Evernia mesomorpha). Both are present in this area.
At the top of the image, there are a few lobes of Hypogymnia physodes, the common monks-hood lichen.
As the Consortium of Lichen Herbaria notes, "Candelariella vitellina is a common and widespread species."
The example shown here – the light green growth – is one of a number on granite and other hard stones in the center of Ipswich. Their age might be measured in decades, certainly not in centuries.
The smaller, lighter-colored growths are apparently moonglow lichens, the dark green an unidentified moss.
Melanelixia subaurifera was formerly assigned to the genus Melanelia The genus cited here, Melanelixia, is a relatively recent one, the subject of ongoing research by specialists. Initially, I had identified the species as M. glaburata. In any case, that would not be not far off.
The surrounding pale green blotches in the image are common greenshield lichens.
My discovery of new lichens seems to be proceeding apace, facilitated by breaking weather, learning what to look for, and encouragement from a bit of recent success.
Xanthoria parietina was first described by Carl Linnaeus in 1753. In North America, it shows a strong preference for coastal habitats, rarely appearing further inland.
As always with things lichen, my beginner's state of knowledge is very modest, in an area where experts may be unsure or disagree. I am relying in my identification on the fact that Xanthoria is well known, and multiple reports that it is common along the seashore of New England.
A few weeks later, I found extensive, even overwhelming growths of X. parietina in headstones in Old South Cemetery, some four miles away. The removed presence of this one on a hardwood trunk is curious.
Now that the stubborn ice of the last months has melted, I have been looking again for lichens during my daily run through the dunes of Crane Beach. There are two that are extremely widespread, common greenshield lichen and reindeer lichen. I had nearly decided that that was it: the sandy soil is almost devoid of nutrients, and whatever grows needs to be salt-tolerant. It is a very specialized ecosystem of a small number of species. Better look in a different place if I want to find something different!
But I was mistaken. Today I came across a new one. I have learned that appearances may be deceiving, but the looks of this one fits classic lichen characteristics very well, on the surface of things. Lichens are made mostly of a fungus, of filamentary composition and usually very light in color, and a lesser bulk of an alga, usually green or less often blue. This growth is a thready, light-green structure.
It is clearly of the genus Usnea, most likely of the species subfloridana (I decided subsequently).
I am excited.
In passing: scrub oak (Quercus ilicifolia) is a long-lived species that has large taproots upon which several generations of above-ground parts may appear. This makes it a good place for a slow-growing twig lichen to be. Why twigs? – I don't know, but I have observed broken-off oak twigs with beard lichens far from any established clusters. It may be that wind-blown twigs are a good vehicle for the lichen to widen its propagation.
Though early January morning weather has been offering a wind chill factor of 0° F, it turns out that there have been good opportunities for field observation, prompted by my new lichen book.
The growth here is a common greenshield lichen, one of the most prevalent varieties globally and locally. It is a symbiotic combination of a fungus (Parmelia sulcata) and a green microalga (Trebouxia).
The microalga component has the capability of photosynthesis, deriving nutrient energy from the air and sunlight. It is notable here that the lichen displays a greenish tint even in mid-winter, in contrast to most of the deciduous plant life around it, now dead, brown and yellow.
The cells of the fungus are filamentary. As my reference notes, these threadlike structures weave into and around the alga, providing a firm base and skin. The durability of the composite is evident in the photograph. The lichen is still present and evidently alive, hanging loosely around the branch, long after the tree itself has died, the bark has dropped, and the wood itself is in marked decay.
Alphabetical by scientific name
© 2025 Paul Nordberg
