Obs. # 268349, 268350, and 268353 for the other parts of this mixed collection.

knowledge down on paper, it would be an encyclopedia. Thanks for sharing it:)

That’s a typical member of concrete retaining wall community. :)

As for C. citrina versus C. flavocitrina — Some would say there is no difference, and only recognize C. citrina. James Lendemer separates the two like this: (note, if this were on granite, say, only C. flavocitrina would be an option according to him)

13a. Thallus +/- squamulose-areolate; soralia marginal; ascospores 10-12 μm long . . . C. flavocitrina

13b. Thallus areolate, often dissolved almost completely into soredia; soralia irregular, spreading to dissolve the areoles; ascospores 11-14 μm long . . . C. citrina

posts. You identified image # 4164 as Caloplaca sp. Originally, I was thinking of Caloplaca crenulatella for that one. Would you buy that? Also, as you’ll note from the caption on image # 4090, I considered Caloplaca citrina. You offered two ID’s for that one. What is the difference between C. citrina and flavocitrina? Can they be told apart without microscopy? THNX

They are much more responsive to small-scale conditions (“microclimate”) than plants or other life forms one typically notices in the field. Not only that, many are also astonishingly consistent and reliable. It gets so once you know an area, you can spot a concrete retaining wall like this with a hint of yellow on it from a distance and know exactly what to expect. All your “old friends” pop up in the same sorts of places time and time again. And it doesn’t hurt that these interesting habitats are often odd and highly-specific things like “underneath a leaning pine, near the ground, with northern exposure, not too far from a stream or in a low spot on the sagebrush steppe which will keep lingering wisps of mist longer than the rest of the landscape”. That’s where you’ll find Mycocalicium subtile and Lecidea holopolia in eastern Washington, for example. I was tasked with locating fresh material of the latter last fall for a study some guys in Graz were doing, and sure enough, it worked > 50% of the time! Good fun.

the Canus lupus familiaris. That’s one I know for sure:)

into individual obs. Seems like lichen love to “share” a good substrate when they find one:) Thanks for lending your eagle-eye, Jason.

I see Candelaria concolor (first photo, yellowest), Xanthomendoza weberi (4th photo, oranger, narrow delicate lobes), Caloplaca sp. (7th photo, orange apothecia), Caloplaca flavocitrina or C. citrina (5, 9-11 are best photos). Oh and Canis lupus.