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Observation 97656: Psora

Substrate: soil.

Habitat: Basaltic Mima Mounds, short grass prairie.

Environmental conditions: semi-arid, totally exposed to sun and wind.

Frequency: only small community (3×5cm) found at site, so far seems rare to uncommon in this particular location, which is may be due to recent grazing history at the refuge..

Thallus squamulose (2-5mm across); Upper cortex: smooth, flat, orangish-reddish-brown; Lower cortex, whitish brown — hard to tell presence, presence of lower cortex was determined using compound scope.
Apothecia black, convex little black balls; on margins of squamules. No soredia or isidia. Seems to be 8 spores per ascus, larger spores up to 18µm, single celled, hyaline.

“A Revision of Psora (Lecideaceae) in North America” by Einar Timdal. The Bryologist, Vol. 89, No. 4 (Winter, 1986), pp. 253-275.
Lichens of British Columbia: Squamulose by Trevor Goward.
Scutari, N. and M. Bertiller, A. Carrera. Soil-associated lichens in rangelands of north-eastern Patagonia: Lichen groups and species with potential as bioindicators of grazing disturbance The Lichenologist 36(6): 405–412 (2004)  2004 The British Lichen Society DOI: 10.1017/S0024282904014008.

Herbarium specimen stored at Eastern Washington University Herbarium.


second photo, the singular one, shows the K+red stain on the epihymenium.
second photo, the singular one, shows the K+red stain on the epihymenium.

Proposed Names

-2% (2)
Used references: Timdal (1986)
Goward (1994)
Based on microscopic features: Epihymenium K+
Based on chemical features: Medulla/cortex: K-, KC ambiguous, C-
45% (2)
Recognized by sight

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= Observer’s choice
= Current consensus


Add Comment
I don’t think this is pink enough to be P. decipiens
By: Jason Hollinger (jason)
2012-06-20 09:26:24 CEST (+0200)

I know the apothecia look marginal, but I think you should consider P. tuckermanii anyway. The K+r epihymenium turns out to be unhelpful — they all do that!