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Do lichens harm plants - is Fellhanera bouteillei a case in point?

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  • 27 Mar 2017 10:28 AM
    Message # 4693620

    Seems to be a common misconception that lichens are generally harmful to vascular plants, e.g. implied by the their abundance on dead and dying trees, although more likely these lichens are just taking advantage of increasing available light. However, it would appear salal and other evergreen plants around here are harmed when their leaves are completely covered by Fellhanera bouteillei. That may be debatable; see these interesting pages (also see p. 85 Robert Lücking Foliicolous Lichenized Fungi. 2008):

    Particularly interesting to me - “In another study undertaken in Costa Rica two researchers carefully removed liverworts and lichens from randomly selected leaves of grapefruit (Citrus paradisi) and an understorey cyclanth (Cyclanthus bipartitus). They found that the denuded leaves suffered 2 to 3 times more damage by leafcutter ants (“one of the most destructive herbivores in neotropical rainforests”) than was the case with the covered leaves. Presumably the chemicals produced by the liverworts or lichens are harmful either directly to the ants or to the ants’ fungus gardens.”

    addition from Field Museum Flickr site

    "However, not all so-called epiphytes are harmless. Some, especially in the family Loranthaceae, are hemi-parasites, since they get nutrients from the phloem of the host tree whereas they maintain their own photosynthesis. Also, a few lichens are hemi-parasites. These belong in the genus Strigula, depicted here in the lower right corner, a genus of lichens growing mostly on living leaves. Strigula associates with the alga Cephaleuros, which is a widespread hemi-parasite especially on coffee, tea, mango, avocado, and Citrus leaves (also known as red dust), taking nutrients very similar to Loranthaceae while remaining photosynthetic. Often it can be observed that Strigula thalli cause leaf damage, even small holes."

    Posting some photos in the gallery. F. bouteillei is quite abundant in some places around here, particularly up around Deception Pass, e.g. one may come across it 6 or 8 times comes along a quarter mile of trail, (although the relative number of plants affected and the number of leaves severely affected is very small).


    Last modified: 27 May 2021 3:31 PM | Richard Droker
  • 21 May 2021 7:25 AM
    Reply # 10529744 on 4693620

    ""We always tell that lichens are harmless to the trees. But some are actually not harmless. Especially most species of Astrothelium (a huge genus of 250 species) are causing most trees to make gall-like callus swellings at least, and often the bark is fissured. Remember this when next you te asked if lichens are harmless." - André Aptroot -

  • 23 May 2021 5:03 PM
    Reply # 10541589 on 4693620
    Bruce McCune (Administrator)

    Two points -- First, it seems safe to answer the question with "They are almost always harmless." The misconceptions are so common on this that the basic message bears repeating.

    Second, I think one could answer the Fellhanera question with a simple little experiment -- mark 40 leaves that have lots of Fellhanera, choose half at random and clean those with a soft cloth and water, then come back a year later and see how many of the leaves are still connected. Depending on the situation you might need to revisit annually for a few years. Another good excuse for a little hike. 

  • 27 May 2021 4:35 PM
    Reply # 10565610 on 4693620

    Particularly low tides motivate Sharon and I to head up to Fidalgo Island (a favorite place with great lichens which I recommend anyone to visit)  tomorrow, and we will begin the experiment you suggest.

    Coincidentally yesterday we encountered what might have been an unfortunate consequence of harmful lichen misconception. On a lichen oriented walk organized by Katherine Glew through Lincoln Park in West Seattle she asked to see the Flavoparmelia caperata I had noticed a month earlier on an ornamental cherry tree along an affluent street south of the park. It was gone. The row of cherry trees had been pruned and looked as if they had been cleansed of lichens.

    Last modified: 27 May 2021 4:38 PM | Richard Droker
  • 28 May 2021 7:36 AM
    Reply # 10569016 on 4693620
    Bruce McCune (Administrator)

    It will be interesting to hear what you find!

    About the Flavoparmelia caperata -- that is a very unusual find, only the second case I know of for that species in the Pacific NW. Was that occurrence documented in some way? Perhaps a photo could be added to the UW herbarium, along with regular label data.

  • 31 May 2021 6:31 AM
    Reply # 10577370 on 4693620

    Sorry to say I couldn’t find leaves with nearly as much Fellhanera as the previously posted photos which were taken four years ago. I have seen similar amounts of Fellhanera covering leaves in other places and expect to do so again, at which time I will try experimenting.

    All I have is 2 photos (hand-held on a neighborhood walk) of the Flavoparmelia in Seattle. I’ll try to have high resolution versions of them added to to the Burke (WTU) collections database. It includes 4 collections of F. caperata which I presume are doubtful (when next there I’ll look at them), from 2 places in the vicinity of Deception Pass. (I wonder if the cherry tree could have originated somewhere where F. caperata is more common, although clearly it had been established on that street quite a long time ago.)

    Regarding the Flavoparmelia photo I posted in the Photo Gallery, I was going to add something about iNaturalist of which one frequently hear pros and cons. It can be very useful when used with care. Seeing Flavoparmelia caperata in Seattle had roused me to check out iNaturalist observations, see I looked at quite a few observation photos, none of which were Flavoparmelia (most were Parmelia). My feeling is that observations seen on a portion of a map that is well out of the known range of a species is often a way of selecting for incorrect identifications. Using iNaturalist to demonstrate ranges of species as was done in several recent Washington Native Plant Society presentations might not be a good idea.

    Possibly of interest is that iNaturalist was useful in finding photos of Acaraspora schleicheri parasitizing Diploschistes muscorum. Of 75 iNaturalist observations one did show them closely associated - ( (As far as I could tell more than 30 were wrongly identified, mostly as other yellow Acarospora species). As I like to mention, when looking for one thing other interesting things are often unnoticed. Recently someone gave me a copy of “A Field Guide to Biological Soil Crusts of Western U.S. Drylands; Common Lichens and Bryophytes” by Rosentreter et al. 2007, which mentioned Acarospora schleicheri parasitizing Diploschistes muscorum, probably often seen but I had never noticed. Looked at my old photos and soon came across some with just that, and one had Acacarospora parasitizing Diploschistes muscorum which was itself parasitizing Cladonia (which seemed some kind of justice), see Besides trying not to miss the inconspicuous another lesson for me was that is worthwhile to read through descriptions even of easily identified species.

    Apologies for going on so long if you have got this far.

    Last modified: 31 May 2021 9:11 AM | Richard Droker
  • 01 Jun 2021 7:55 AM
    Reply # 10580304 on 4693620
    Bruce McCune (Administrator)

    Excellent photo of the Flavoparmelia caperata, which looks happy and healthy.

    That is a spectacular example of iJunk on iNaturalist! I just looked at a handful, all of which were clearly something else (Parmotrema, Parmelia, Melanelixia, etc.). 

    Interesting to compare the iNaturalist with CNALH. Makes the latter look pretty darn good (though most lichen people know you can't use that uncritically either).

  • 03 Jun 2021 4:29 PM
    Reply # 10589110 on 4693620

    Richard, wonderful that you could see those layers of parasitism happening on the desert species Cladonia spp., Diploschistes muscorum and Acarospora schleicheri. Heather Root tuned me into them. I use them as a rough timeline when trying to figure how long a place has been undisturbed by grazing (since most of my desert work has been on BLM grazing leases). I figure Cladonia can show up about 5 years after a soil-scouring event. Diploschistes maybe takes another 5-10 and then using something like 1mm per year radial growth, you can guess how old the Dip is. And I have sort of guessed that the Acarospora gets there at least 25 years after colonization by the Clad. It would be super if someone started a watching experiment now, so we could have a better idea in 20 years!

  • 06 Jun 2021 5:23 PM
    Reply # 10598886 on 4693620

    Wow - that's really interesting. I would have thought that Diploschistes was a faster growing lichen. I'm a little old for long term experiments, but I'l keep an eye out for good prospects.

    Also interesting is D. muscorum switching from Trebouxia irregularis taken from Cladonia to T. showmannii, and probably more scenarios known to you.

    Last modified: 06 Jun 2021 5:23 PM | Richard Droker
  • 07 Jun 2021 8:03 AM
    Reply # 10601286 on 4693620

    So Daph, the Lava Beds has been free of grazing for about 60 years. I have Diploschistes that are 2 inches or more and Acarospora schleicheri near the same size. How old would guess these are? I have a measurement project there now for the next 5 years (assuming I make it, I’m 70 now), I could add a Dip into my playtime. 

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