Observation 13044: Rhizocarpon geographicum (L.) DC.

Notes:
crust lichen, on granite
THALLUS: lemon yellow, rimose-areolate, smooth to powdery surface, convex, up to 1 mm thick, cortex thick
MEDULLA: white, K-, P+y
ALGAE: green
APOTHECIA: immersed, black; hymenium to 200 µm, hyaline; epihymenium brownish, 25-35 µm; hypotheicum black-brown, very thick; paraphyses matted together
SPORE: 8 per ascus, muriform, 8-12 cells?, football-shaped, ~30 × 15 µm, grey becoming dark brown

Images

Just a thumbnail.
Apothecia, at 30×.
Thallus cross-section, at 30×.
Apothecial section, in water, at 100×.

Proposed Names

87% (1)
Used references: Nash’s Sonoran Flora
Based on microscopic features: medulla PD+ yellow
Based on chemical features: muriform brown spores

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= Observer’s choice
= Current consensus

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Created: 2008-10-23 14:17:06 PDT (-0700)
Last modified: 2008-10-23 14:17:06 PDT (-0700)
Viewed: 33 times, last viewed: 2019-01-23 12:40:41 PST (-0800)