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Rhizocarpaceae 
 Haugania oederi (Rhizocarpon oederi) Growth type crustose Chemical results negative. Epithecium olive to dark green Usually an upland species on exposed, iron-rich rocks, often associated with mines or quarries. Patches of areolate or rimose orange or rusty-red thallus with black umbonate or gyrose apothecia. The spores are colourless, 3-septate. Microscope photographs below. Similar: Tremolechia atrata and Lecidea lithophila  | 
	
 
Microscope photographs
Haugania oederi (Rhizocarpon oederi)
On ironstone. Studland Heath, Dorset. May 2015