Chrysothrix granulosa

Chrysothrix granulosa, the coastal gold dust lichen, is a brilliant yellow, powdery (leprose) lichen that grows in irregular patches mostly on bark (sometimes wood and rock) in shaded dry areas of coastal western North America and western South America.[1]^: 253–4[2]

Coastal gold dust lichen
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Ascomycota
Class:	Arthoniomycetes
Order:	Arthoniales
Family:	Chrysotrichaceae
Genus:	Chrysothrix
Species:	C. granulosa
Binomial name
Chrysothrix granulosa G.Thor (1988)

In North America it is found from Mexico to as far north as British Columbia.[1] It can be found in coastal areas of California[1] near Santa Barbara County,[2] and coastal areas of the Sonoran Desert, mostly islands off Baja California.[2] In South America it is found from Chile to Peru.[2] It is found at elevations from sea-level to 400 metres (1,300 ft).[2]

The mostly structureless body (thallus) forms powdery cushions of lichen granules (soredia) over a fluffy middle layer (medulla).[1] The upper medulla is yellow fading to yellow-white in the lower part.[2] It lacks fruiting bodies (apothecia).[1] Fruiting bodies (apothecia are absent in populations in California and the Sonoran Desert, and elsewhere have a constricted base with 0.2 to 1 mm diameter brownish orange flat to convex discs.[2]

Lichen spot tests are K+ orange, C-, KC-, and P+ orange, with UV+ a dullish dark orange.[1] Secondary metabolites include calycin acid and diffractaic acid.[1]