Yes and sunspots could effect the greening as well? You may actually have another Xanthoria or a Caloplaca:
Parietin
Parietin - Wikipedia
What wiki does not say is that parietin is an anthraquinone, so one may compare other structures of anthraquinones, and that parietin occurs externally on the lichen:
'Apothecia lecanorine, sessile or short stipitate; disk concave to becoming convex, yellowish orange or orange or orange reddish; hypothecium hyaline to pale brown; hymenium hyaline below, with anthraquinone crystals above; paraphyses capitate, sometimes containing oil droplets; spores 8, ellipsoidal to cylindrical, 2-celled, polariocular. Pycnidia immersed; condia short cylindrical or ellipsoid.'
(Thomson, Lichens of Wisconsin)
The parietin study, of course, used pure parietin, separated from its naturally-occurring context. Outer crystals would mean that rain could wash the parietin into a drinking basin for animals. When considering the entire lichen, one cannot be sure of the effects or anti-effects of the other constituents. It would be interesting to know abgouot the oil.
Parietin
Parietin - Wikipedia
What wiki does not say is that parietin is an anthraquinone, so one may compare other structures of anthraquinones, and that parietin occurs externally on the lichen:
'Apothecia lecanorine, sessile or short stipitate; disk concave to becoming convex, yellowish orange or orange or orange reddish; hypothecium hyaline to pale brown; hymenium hyaline below, with anthraquinone crystals above; paraphyses capitate, sometimes containing oil droplets; spores 8, ellipsoidal to cylindrical, 2-celled, polariocular. Pycnidia immersed; condia short cylindrical or ellipsoid.'
(Thomson, Lichens of Wisconsin)
The parietin study, of course, used pure parietin, separated from its naturally-occurring context. Outer crystals would mean that rain could wash the parietin into a drinking basin for animals. When considering the entire lichen, one cannot be sure of the effects or anti-effects of the other constituents. It would be interesting to know abgouot the oil.