I find some gray lichens

Update: these are not Phaeophyscia hirsuta.

Some time ago the local park had been specially redesigned for the recent California water conservation program; earlier this month I went there and saw a sign mentioning that the vegetation and sidewalks were carefully arranged to neutralize the "heat island" effect of cities. I saw several lichens during my walk; these were mainly yellow and orange dots on some areas of aboveground concrete/roots and tons of gray foliose thalli on tree trunks (especially the bases).  I was quite thrilled to see further evidence of the "lichen sparsity in urbanized southern CA is caused mainly by heatstroke" hypothesis.



I captured some of the ubiquitous gray thalli (all others were in positions which could easily have been contaminated with vertebrate secretions) and was informed that they were probably Phaeophyscia hirsuta in a mostly hairless phase. Researchgate and JSTOR informed me that P. hirsuta was:

- a facultative nitrophile (it voraciously eats nutrients from car exhaust)
- adapted to xerothermic environments
- apparently an obligate shade-loving species
- also capable of growing on mosses (this probably means that captive specimens can colonize glass/plastic)
- calcium-preferring (fortunately all my water is hard water)

Based on my field observations, it probably makes its xerothermic adaptations compatible with its sunburn intolerance by growing in shaded places with hot air (lawn sprinklers were often nearby, though; one website I visited did say that it was capable of facultatively colonizing mesic areas).



Perhaps even stranger than its fear of sunscorch, however, is its conservation status. Currently it is listed as "globally vulnerable" on iNaturalist. I was initially quite alarmed at this, having taken precautions to only collect hyperabundant weedy species. However, the iNat status seems to be erroneous; all recently published P. hirsuta literature I found agreed that it was common/widespread in CA (phew!) To complicate matters, it is apparently in severe Canadian danger though: https://www.pnwfungi.org/index.php/pnwfungi/article/view/1266



I am keeping my samples in a manner consistent with the above-listed ecological preferences, with a hydration schedule of 12 hrs every two days, and have propped them up on a boiled stick to increase ventilation. Unfortunately the thallus surface is quite hydrophobic and thus has been constantly causing scheduling errors. Hydrophobicity in a lichen implies that the species in question may be vulnerable to excessive water absorption, which interferes with the physics of carbon dioxide capture and thus photosynthesis; however, in captivity the water repellence makes it difficult to water the thalli without violently soaking them. I really need to get a non-moldy mist bottle so I can stop using the tap!

Here are some pics (click to zoom, as always); it took me large amounts of effort to make the photographed colors accurate, and I even ruined several (not shown) samples by accident in the process.

dry (beautiful ivory colors!)

freshly soaked (it greens instantly!)

Unfortunately, more testing is needed. The specimens shown have not visibly grown yet, and I have not fertilized them yet (normal liquid fertilizers are probably a suitable replacement for noxious car gases, though). I have also discovered several dark maculations on some of the thalli, which might be parasitic fungi; they may be scientifically interesting and/or dangerous to the culture. Stay tuned for further updates!













Postscript: bonus research papers

https://link.springer.com/article/10.1007/BF00333715 (Pure acetone can also be used for disinfecting dry lichens non-fatally, which is useful; however it may wash away antibiotics created by the lichen. Fortunately P. hirsuta has no known secondary metabolites)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2710189/ (Hydrophobicity and pollution tolerance are linked)