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Lichen Substrate Host-specificity- Trees with photosynthetic bark

  • 09 Apr 2017 12:45 PM
    Message # 4738430

    Does anyone here know of any lichen species (preferably in California but this being the page for lichenologists of the Northwest, I'll take the exceptions) that ONLY grow on the bark of trees that have photosynthetic bark? Irwin Brodo's book mentions 3 species that are endemic to trees with photosynthetic bark, but the distribution maps showed that their range is limited to the east coast Florida area. I'm hoping we have our own western counterparts. The trees I can think of off the top of my head that have photosynthetic bark are Quaking Aspens (Populus tremeloides) and Palo Verde (Parkinsonia florida/ Parkinsonia microphylla), but there must be more. So I guess this post poses two questions: what trees with photosynthetic bark do you know of, and do you know of any lichen species that grow only on those trees? Thanks! 

  • 10 Apr 2017 1:13 PM
    Reply # 4740110 on 4738430

    That's really interesting that some lichens only grow on photosynthetic bark!

    Pacific Madrone (Arbutus menzuesii) has green bark which turns red and peels off to reveal more green, e.g., more extreme than usual but Mark (Castilleja authority) says its not enhanced. Seems to discourage lichens but would be interesting to note which ones do grow on it.

    Last modified: 10 Apr 2017 1:13 PM | Richard Droker
  • 11 Apr 2017 7:38 AM
    Reply # 4746259 on 4738430
    Bruce McCune (Administrator)

    I believe that most woody plants have photosynthetic bark when the stems are young, but that they vary a lot in how quickly this is lost. I just went outside and scratched twigs of Viburnum, Rhamnus, and Cornus with a fingernail -- all bright green.

  • 11 Apr 2017 5:08 PM
    Reply # 4747225 on 4738430

    Don't forget Acer circinatum! Not many spp on it, but I think I see a very thin, whitish thallus that has a nice white prothallus. Haven't ID'ed that, though.

  • 12 Apr 2017 12:01 PM
    Reply # 4748855 on 4738430

    By my reading, the bark is photosynthetic in virtually any woody plant with smooth bark. A contrary example would be interesting.

    The benefits of recycling: how photosynthetic bark can increase drought tolerance

    [quote]In this issue of New Phytologist, Vandegehuchte et al. (pp. 998–1002) bring this process into the spotlight, and provide a compelling argument for why we should take more notice of that often-hidden, green layer of tissue that is ubiquitous beneath the smooth-bark surfaces of woody plants (Scott, 1907; Pfanz et al., 2002; Dima et al., 2006; Rosell et al., 2015).


    The far more common stem photosynthetic syndrome is one in which chlorophyllous cells in the bark cortex refix a portion of the CO2 respired by the underlying tissues or carried into the stem segment by the transpiration stream as it diffuses from inside the stem to the atmosphere. This kind of stem photosynthetic activity likely takes place in all shrub and tree species that have smooth bark surfaces. In some of these species, smooth bark will be found on only the youngest stems, whereas in others (e.g. some Eucalyptus species) smooth bark will be maintained as the stems age and increase in diameter through successive shedding of dead bark layers (Pfanz et al., 2002; Cernusak & Hutley, 2011). [/quote]


    In the case of Madrone that Richard mentions, the shedding of the bark may be sufficient to discourage lichens. ? I have seen lichens growing on dead branches of Madrone at Limestone Kiln Lighthouse on San Juan Is. 


    Adding 'scratch through bark' to my remember-to-do-in-the-field list. :) 


    Last modified: 12 Apr 2017 12:36 PM | Roger George
  • 17 Apr 2017 5:25 PM
    Reply # 4757681 on 4738430

    Noticed 2 understory trees/shrubs with photosynthetic bark that seem to be devoid of any Macrolichens; Oemleria cerasiformis , and Lonicera involucrate. Detail images in Gallery.

  • 19 Apr 2017 2:48 PM
    Reply # 4764180 on 4738430

    Roger, on the understory trees/shrubs, is there enough sunlight filtering through that lichens would even want to grow there?

  • 19 Apr 2017 5:04 PM
    Reply # 4764378 on 4764180
    Steve Sheehy wrote:

    Roger, on the understory trees/shrubs, is there enough sunlight filtering through that lichens would even want to grow there?

    The particular Indian Plum I sampled is on the edge of a Garry Oak grove and has a southern exposure to grassy prairie. The particular Twinberry is nearby & more shaded, being a bit further from the edge but still with southern exposure.


    There are several types of forest on the preserve and I'll be keeping an eye out for more particulars throughout. We also have Hawthorns and these often are covered in lichens even in shaded conditions. Other understory trees/shrubs on site that I haven't check include Cascara, Vine Maple, Oval-leaved Viburnum, Pacific Ninebark, Red Elderberry, and Saskatoon.

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