Vexations with Lichens - a year later! The case of Lepraria pacifica

In August of 2017, I wrote a journal entry about some of the difficulties for me, as a beginner, with the study of lichens. I have made some progress since then, for sure, but I am not yet utterly humiliated by my complaints back then. Here's a link to that entry -

My primary complaint today is a simpler, more specific one. I spend a lot of my hiking and lichen-ing time in the Redwood (and mixed Redwood) forests of San Mateo county. The Coast Redwood (Sequoia semperviren) often has a greenish dust lichen on its trunk, near the base. Sharnoff says that Lepraria pacifica is one of the only lichens that will grow on the base of S. sempervirens, and this is attested, too, in the article about this species from Wikipedia by Lendemer (used in the species account here on iNaturalist -

So here are my vexatious questions

  1. IF there are other species of dust lichens that can tolerate growing on S. sempervirens, what are they?
  2. IF these other species exist, what is the relative percentage/likelihood of their occurring in San Mateo county or coastal California? Lepraria is not the most heavily populated among lichen Genus, with less than fifty worldwide ( Bordo lists twelve North American species, though that book adds that the genus has not been studied systematically in North America.
  3. CAN L. pacifica be told from L. finkii visually in the field? AND do we know if L. finkii can and does grow on Sequoia sempervirens?
  4. RELATED to that, what other crustose/squamulose lichens (either Lepraria or any look-alikes) DO adopt Sequoia sempervirens' bark as substrate?

I ask because my statistically justifiable but audacious naming of this green dust lichen on the base of a redwood tree in the midst of unrelieved redwood forest as Lepraria pacifica would constitute the FIRST San Mateo County record in iNaturalist. Since that seems an unlikely occurrence given what is written about L. pacifica's habitat preferences, I have to assume that everyone but me knows the answers to the questions above, OR knows they can't be answered, OR is afraid that there are crypto-species or unknown species out there that could throw this whole thing into doubt.

Thanks for listening! I'll tag some likely suspects in the comments section.

THANKS TO ALL who are generously sharing your lichen knowledge and cautions with me, a rank beginner 😊🌲(somewhere on this tree, there is lichen. You know it, and I know it. We await the day when there is an emoji for lichen, other than 🤯)

Publicado el octubre 28, 2018 05:29 TARDE por gyrrlfalcon gyrrlfalcon


Fotos / Sonidos




Octubre 27, 2018 a las 02:52 TARDE PDT


On Coast Redwood


I feel your pain

Publicado por dpom hace más de 5 años

I feel it even more painfully than you.

Publicado por leslie_flint hace más de 5 años

I used to truly think I could identify what I was looking at - not crustose lichens, though... I never really had any skill there, if I am honest. Professional lichenologists have politely sniggered all these years, but they never made me feel bad.

Recently, I collected a lichen in my par of MN that I believe is Vulpicida juniperina. Maps show this species to grow in alpine/arctic conditions in the west and Yukon. Could it be here?! I sent a collection to one of those polite and honest lichenologists. She warned me - in these exact words - "Whatever you've found is a morphological anomaly/ecotype, a strange disjunct, or, who knows, something new." She is going to help. "I'll try to get that DNA extracted and amplified in the first week or two of November."

So you see, I suspect that what you are asking requires more. Until that point, I suggest you should keep on keepin' on!! Explore, find cool things, post them, make bold predictions, then show humility when those who know more correct you. The power of iNaturalist doesn't lie in identifying things exactly. The power lies in locating those possibilities that could lead others to deeper discoveries. We provide the eyes in the woods and the feet on the ground.

I don't mind being wrong 1000 times if one other time I ignorantly stumble across an amazing discovery that means something to a "real" scientist... whoever she may be.

Publicado por jwalewski hace más de 5 años

Sigh. I get it, and by asking about lichens on the bases of redwoods, you have inadvertently placed us both on the same level of understanding. By sheer luck and the capriciousness of fate I happen to know a fair number of canopy researchers who have spent a lot of time in the tops of redwoods. Since I have a terror of heights I have never joined them, and the lichen flora they tell me about excites me no end. So off I go to the redwood forest, where disappointment awaits me. I don't spend much time on these genera: Usnea, Cladonia, or Lepraria unless I must, because I find them difficult. Of course, the two genera most common on the trunks of redwoods are Lepraria and Cladonia. Numerous species, or just a couple? I don't know.

As for Lepraria pacifica vs.L. finkii, Lendemer's key published in the Lichenologist splits the species this way:

1b. Thallus not both K- and KC+ gold-yellow...........................8
8a. Thallus UV+ blue-white.................................................9
9a. Western N. America....................................... L. pacifica

Thallus not UV+ blue-white
leads eventually (another 6 key steps) to L. finkii, ubiquitous in eastern N. America, but involves additional spot tests and TLC.

So you have options: 1) do your statistical thing & call it L pacifica; 2) do the chem test, which increases your stats thing; 3) get a UV lamp & do the test. At this point, if the spot tests agree and the UV test agrees, it's L. pacifica. If any tests differ, then down the rabbit hole you go. As for the 50 spp worldwide, it's not enough - here are some species (just within N. America) that are not in iNat: aurescens, barbatica, cryophila, disjuncta, finkii, harrisiana, hodkinsoniana, knudsenii, moroziana, neglecta, nothocaesiella, oxybapha, terricola, textum, xanthonica.

The trouble with the whole "statistical" thing brings on my fairly constant tirade about the 1000:1 ratio of knowledgeable lichen folk vs. knowledgeable bird/plant/mammal folk. Bird biogeography is pretty well known, so if you are at such-and-such a place and you see this that and the other, you can be pretty sure of the name you put on it. With lichens, maybe no one has ever stood where you are standing, and your questions 1, 2 and 4 are being asked by someone accustomed to a discipline that already has a really well-developed "flora". With lichens, it's a whole new world and nobody knows these answers.

Publicado por tom_carlberg hace más de 5 años

Thanks so much, Tom, for your comments. I figured it was an answer of this sort, but it is helpful to know it from you! As to that 1000:1 ratio of knowledge, my friend and VT iNat-ter @charlie , gave me the phrasing I use about that. He said, somewhat sheepishly but also with pride, "Jennifer, I'm not saying that birds are overstudied...but compared to birds, everything else is under-studied." This statement by Charlie is one of the motivating factors that led me to care about lichens.

Publicado por gyrrlfalcon hace más de 5 años

that's awesome!

Publicado por charlie hace más de 5 años

You're welcome, for all that it helps you. I wonder if I'm still underestimating? 10,000:1?

Publicado por tom_carlberg hace más de 5 años

Googling L. pacifica brought me to this page and to a lovely photo of the lichen in Yosemite along with a chatty article by the PhD student who named it. His statement [pg 3] that "contrary to popular belief, there [are] discrete micro­morphological differences between Lepraria species" does not seem very encouraging. MICRO-morphological. Right.
Nonetheless, you might enjoy the article if you haven't yet read it.

Publicado por nancyasquith hace alrededor de 4 años

sounds like another group that needs subgenus sections

Publicado por charlie hace alrededor de 4 años

Ah! The Church of the Subgenus!

Publicado por gyrrlfalcon hace alrededor de 4 años

Thanks @nancyasquith - I'll be at the CALS meeting this coming weekend!

Publicado por gyrrlfalcon hace alrededor de 4 años

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