Observation 91764: Physcia aipolia (Ehrh. ex Humb.) Fürnr.

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Recognized by sight: Pertusaria? on deciduous wood

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Need to look at totally different things for lichens
By: Jason Hollinger (jason)
2012-04-04 20:26:26 -03 (-0300)

Yeah, it’s a pain at first. It’s all about getting a feel for which things are just random environmental variation, and which are consistent characters useful for identification. But it goes quickly because there are relatively few macrolichens. (At least compared to fungi in the larger sense!)

By: Gerhard Koller (Gerhard)
2012-04-04 20:15:51 -03 (-0300)

I’ll learn but it is irksome :)

Foliose lichens
By: Jason Hollinger (jason)
2012-04-04 20:02:31 -03 (-0300)

Pertusaria is a crustose genus, meaning it cannot be removed from the substrate without damaging it or the substrate. These specimens are all foliose, so they have a lower cortex separating them from the substrate. You should be able to pry them away from the bark using a knife with minimal damage to either the lichen or the bark.

In this case, I think the first two photos are probably Physcia aipolia or P. stellaris; and the third photo is probably Parmelia sulcata. There are a few differences to look for: Physcia has smaller lobes (< ~3 mm wide), the surface is pale, dull, minutely-mottled gray; Parmelia has broader lobes (many exceeding 3 mm in width), the surface is a darker, more bluish, shiny gray with (and this is critical) a network of coarse cracks in the surface. You would also see differences on the lower surface: Physcia is almost always white below with short, white, unbranched rhizines; Parmelia will be black with tangled, black, often branched or squarrose rhizines. Chemistry also differs: both react K+ yellow on the surface, but Physcia is K+/- yellow in the cottony white medulla inside, while for Parmelia the medulla is often K+ yellow turning bright, deep red within a few seconds.

Physcia stellaris?
By: zaca
2012-04-04 19:54:55 -03 (-0300)

Created: 2012-04-04 19:33:43 -03 (-0300)
Last modified: 2012-04-04 20:03:17 -03 (-0300)
Viewed: 49 times, last viewed: 2017-06-12 22:49:26 -03 (-0300)
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