When: 2017-02-14

Collection location: West St. Louis Co., Missouri, USA [Click for map]

Who: Judi T. (AvidAmateur)

No specimen available

On live, mature Honey Locust tree on residential common ground.


Copyright © 2017 Judi Thomas
Copyright © 2017 Judi Thomas
Copyright © 2017 Judi Thomas
Copyright © 2017 Judi Thomas
Copyright © 2017 Judi Thomas
Magenta bar indicates where bright yellow medulla is exposed.

Proposed Names

1% (2)
Recognized by sight
31% (2)
Recognized by sight
56% (1)
Recognized by sight

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= Observer’s choice
= Current consensus


Add Comment
I know
By: Jason Hollinger (jason)
2017-02-17 09:34:57 JST (+0900)

That’s why I suggested both the scratch and UV tests — they never get old. Haha! It’s always a rush to find that “heart of gold”. Or to flick on the UV lamp and see it spring to life. Endlessly amusing. :)

Cool! I just got excited at the idea of scraping off
By: Judi T. (AvidAmateur)
2017-02-17 09:27:11 JST (+0900)

the cortex to see what color the medulla is. My knowledge is still so basic that I get cheap thrills:) Whenever you mention something I can’t wait to try it or check it out. Thanks for all the tips.

Yellow medulla is in both, I think(?)
By: Jason Hollinger (jason)
2017-02-17 08:52:53 JST (+0900)

You’re looking for the cortex to fluoresce in UV. It’s got lichexanthone instead of the usual atranorin in it. I don’t have a photo of this species fluorescing, but I do have a photo of Hypotrachyna osseoalba doing it. It has the same pigment in its cortex. This is what you should see if it were P. subcinerea. Not subtle! :) Especially in a dark room or at night.

Went back to the Locust tree this afternoon and
By: Judi T. (AvidAmateur)
2017-02-17 08:18:42 JST (+0900)

broke off a piece of bark to bring home for more study. Scratched off the surface of the lobe with an awl (thanks for the tip) and exposed a bright yellow medulla. Added image # 4899 which was taken under a “cheap-o” LED flashlight. Does this mean we have P. subcineria instead of sorediata here?

Might be worth carrying a UV light at first, too!
By: Jason Hollinger (jason)
2017-02-17 04:45:28 JST (+0900)

The UV+y is pretty obvious, even with a cheap-o LED flashlight, just shade the subject as much as possible (or go for a walk at night!) P. subcinerea is the UV+ yellow one. Just wander around the woods around your house at night shining the LED light at the trees and it’ll pop right out. :)

Anyway, that might be a good way to confirm your interpretation of the pruina until you “get it down”.

The orange-pink… “mustard”, that’s a better description… it is hidden in the medulla. You’ll have to scratch the cortex off or damage it in some way.

P.S. Does that orange-pink color show
By: Judi T. (AvidAmateur)
2017-02-17 04:37:19 JST (+0900)

itself with chemicals? Which ones would bring it out, or is UV needed?

Well, that’s creepy. While cruising through
By: Judi T. (AvidAmateur)
2017-02-17 04:29:40 JST (+0900)

the photos on your web site I decided my ob must be either sorediata or subcineria. I couldn’t determine the difference. Now I see it! Thank you SO much for teaching me that. Next time I encounter Pyxine I hope I have my hand lens with me. Last time I was just walking the dog … camera only.

And it’s a beautiful salmon-orange-pink color inside!
By: Jason Hollinger (jason)
2017-02-17 04:03:22 JST (+0900)

Take another look, if you would, at photos of P. sorediata and P. subcinerea, side-by-side if possible. Pay close attention to the pattern of pruina on those adorable lobe tips. It is actually possible (thanks to Malcolm Hodges for pointing this out to me!) to distinguish the two in the field without a UV lamp. For you, P. sorediata may be more common. But I bet you have both.


Thanks, fellas. After your suggested genus, Zaca, I went
By: Judi T. (AvidAmateur)
2017-02-17 03:41:25 JST (+0900)

on your Ways of Enlichenment web site, Jason, to familiarize myself with all the species of Pyxine when you narrowed it down for me. Those little spoon shaped thalli are adorably distinctive. This is a new one for me. Thank you both for your help.