Observation 193466: Peltigera rufescens (Weiss) Humb.

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Yes… when wet
By: Jason Hollinger (jason)
2014-12-21 10:58:21 PST (-0800)

P. canina s. str. will usually be very pale hoary whitish-brownish-gray when dry (just like rufescens).

Notice the undulating texture in the upper surface, too. P. canina s. str. has thinner lobes (relative to breadth at least) so it usually wrinkles up like this. (P. membranaceum wrinkles up like this even more, perhaps because it has the thinnest thallus among the canina group.)

Here’s another useful character, in my opinion: P. rufescens tends to grow in drier places, often directly on soil, and it forms a dense but relatively short woolly mass of rhizines. So it tends to be very difficult to clean off the underside. Very frustrating at first, but then once I figured this out, I started using this very thing as confirmation! Its veins are supposed to turn black toward the center, but this is usually difficult to verify given how messy the underside is with all the dirt and tiny bits of debris all tightly tangled up in the tomentum. P. canina, P. praetextata, P. membranaceum, etc., on the other hand, should grow more loosely, usually attached to nice “clean” substrates like leaves, moss, twigs.

Thanks for the tutorial!
By: Andrew Khitsun (Andrew)
2014-12-21 06:46:40 PST (-0800)

That last photo shows very great flattish-looking specimen, and because of the flatness of it the lobe tips stand out even from afar. I understand from your comments below this is how P.canina is expected to look.
P.S. And I just added a photo of the underside (bottom photo).

This is a great example…
By: Jason Hollinger (jason)
2014-12-21 01:43:21 PST (-0800)

…of how difficult it is to rigorously define what’s meant by “lobe tips down-turned”. This photo shows lobe tips clearly turned-down:

But then this one shows all the margins and tips vertical and not down-turned at all:

This, on the other hand is what is really meant by “lobe tips down-turned”:

I find that if I think about it too much it all goes to pieces! :)

I struggled to determine whether the lobe tips are upturned or downturned.
By: Andrew Khitsun (Andrew)
2014-12-20 19:28:55 PST (-0800)

To me it looked like the lobe itself is facing up, but the very tip is facing down. I don’t have too many P.canina observations (plenty of P.praetextata though), so don’t know that species well enough. As far as underside goes – so far I didn’t master taking good photos of it in the field. I think the lobe tips underneath are not very representative: the rhizines are different than those towards center of thallus, color is usually lighter, you can’t see those pits and veins well etc. So I’ll try taking photo of the lower side of this specimen in a staged situation – when “in captivity”.

By: Jason Hollinger (jason)
2014-12-20 13:12:26 PST (-0800)

True P. canina (rufescens used to be a subspecies of canina) is broader, thinner, turns down at margins (not erect like this), and usually has an undulating texture. Don’t forget to get photos of the underside of this genus! A good habitat to get into is turning over one lobe of every specimen you see. It doesn’t necessarily have to damage the specimen, even. The more you see, the more the characters of the veins and rhizines will begin to make sense.

Light tomentum present,
By: Andrew Khitsun (Andrew)
2014-12-14 10:12:44 PST (-0800)

lower surface all white, even towards the center. Rhizines spaced-out and long, splitting into several sometimes intertwining cords.

Created: 2014-12-14 09:40:59 PST (-0800)
Last modified: 2014-12-21 07:36:36 PST (-0800)
Viewed: 56 times, last viewed: 2017-06-19 12:52:42 PDT (-0700)
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