I would appreciate confirmation of my inference that X. fulva only occurs west of the Rockies in North America. My sole information is that in Lindblom’s paper (The Bryologist 109(1): 1-8. 2006) all of the specimens she sites for X. fulva are from Alberta, Montana, Wyoming, Colorado and westward. And she says that her new concept of X. fulva s. str. corresponds to the “western morph” as described in her 1997 paper (which I don’t have access to). Nowhere does she explicitly say that all eastern material has to be X. weberi.

I’ve never heard of X.weberi, but it helps to peg some specimen. The most frustrating part is when you have a range of specimen and it looks like you’re dealing with half a dozen species, but supposedly there are only couple species in the area that you can choose from. I’m still concerned, though. While this observation looks like (some parts of) observation 88906, I don’t see much resemblance with observation 88901. And where does it leave observation 88899 and observation 88900? I wish X.fulva wasn’t “banished” from the region. My brain hurts too.

Now I do see some prominant orange pycnidia in the top photo. Oh hell, I give up.

Now, seeing the full set of your observations, it is less clear that this is fulva/weberi. Compare this to observation 88900 and observation 88901. This is too broad-lobed. I’m beginning to think this is just a particularly well-developed specimen in which the central lobes are being crowded into a semi-erect position. Compare the lobe width on these to those in observation 88901. Also, note what the prominant pycnidia look like in that observation. There are none of those anywhere in any of these photos. Granted, I don’t know where the rhizines are hiding in these photos, either… As for the soredia, I think again, I wonder if these are just very well-developed in the center, causing the initially marginal soredia to coallesce into long soralia all the way around the tips of central lobes.

These thalli are damp, right? I see some orange spots near the tips of some lobes. I thought they were necrotic zones at first, but maybe they are pycnidia?

In any case, the semi-erect lobes with soredia under the tips (not just under the margins) seems to clearly indicate this is X. fulva.

Note the difference between X. fulva and X. weberi… (See Bryologist 109(1): 1-8)

X. fulva – orange to dark orange, irregular branching, strictly western?
X. weberi – yellow to orange, branching distinctly dichotomous, strictly eastern

I think this means X. fulva s. str. is not present in Great Lakes region. Note that there was something called X. wetmorei in Wisconsin but Knudsen et al. 2011 synonymized that recently with weberi.

Brodo et al. in Lichens of North America 2001:

X. ulophyllodes – rhizines abundant, pycnidia inconspicuous
X. fulva – rhizines absent or sparse, pycnidia conspicuous (orange “pimples”)

Hinds & Hinds in New England Flora 2007:

X. ulophyllodes – lobes 0.4-1.7 mm wide, flatter and wider, soredia marginal to submarginal
X. weberi (recent segregate from fulva) – lobes 0.2-0.6 mm, narrow, soredia underneath hoods at apices of semi-erect lobes

British Flora 2009 (2nd edition):

X. ulophyllodes – lobes horizontal, appressed, 5-8 mm long, blastidia marginal, often sparse
X. fulva – lobes mosty ascending, 1-2 mm long, blastidia covering entire lower surface, visible when viewed from above

[note: they claim both have rhizines]

Lindblom in Sonoran Flora, vol. II, 2004:

X. ulophyllodes – rhizines abundant, rosette-like
X. fulva – rhizines absent or sparse, forming colonies

[note: also mentions that fulva has narrower lobes in the notes]

Harris in Ozarks Flora 2005:

X. ulophyllodes – lobes prevailing > 0.6 mm broad, soralia primarily labriform and marginal and > 0.5 mm long
X. fulva – lobes < 0.5 mm broad and prevailingly ~0.2 mm broad, soralia marginal and terminal and < 0.4 mm long

A bit hard to summarize, because there are apparently some disagreements, but creative interpretation allows them to be reconciled, e.g., rhizines must be present in both, just sparse in fulva.

X. ulophyllodes – lobes broader and appressed, rosette-forming, rhizines common, soralia marginal, pycnidia inconspicuous
X. fulva – lobes narrower and semi-erect, colony-forming, rhizines sparse, soralia covering lower surface near tips, pycnidia conspicuous like orange pimples

[EDIT: It’s worth noting that the same analysis applies for oregana as well. The differences between oregana and ulophyllodes are very subtle, and require a comment of their own. But oregana is not present in the Great Lakes region.]

I really don’t know the difference between X.ulophyllodes and X.fulva, until someone points it out to me. Wrong or right, I believe most of my photos of “furry” Xanthomendoza with lobes standing up (almost) and rosettes coalescing, are X.fulva, but the ones with more defined flattish rosettes are X.ulophyllodes.

(X. oregana not in your area.)

I’d always thought of X. fulva as a much smaller species which grows in diffuse colonies, instead of well-defined rosettes like this is trying to do. But this really does look like Sharnoff’s photos of X. fulva.