When: 2017-04-30

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

Who: Judi T. (AvidAmateur)

No specimen available

On mature live Pin Oak in suburban residential area.


Copyright © 2017 Judi Thomas
Copyright © 2017 Judi Thomas
Copyright © 2017 Judi Thomas

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Yes, side-by-side is a great way to learn
By: Jason Hollinger (jason)
2017-05-03 11:12:14 CDT (-0400)

these subtle characters. It’s the way with lots of characters, not just in fungi and lichens. You pretty much have to see all the species in the key once before the couplets all make sense. Once you see the thing it’s “oh! that’s what they mean! that’s totally different”.

Stick with it. One of these days, trust me, you’ll get it and you won’t be able to remember why it was ever so difficult. :)

Shame on me. I made the exact same mistake on
By: Judi T. (AvidAmateur)
2017-05-03 11:03:25 CDT (-0400)

the identification of my Ob. # 265706 and you corrected me then, Jason. I’m still having trouble telling these two apart. Think I’ll have to see the two side by side before I can “get it.” THNX!

Probably too green because wet
By: Jason Hollinger (jason)
2017-05-03 10:54:56 CDT (-0400)

The things you want to pay attention to in this case are the texture of the upper surface especially (very finely reticulately cracked) and the soralia (powdery poofs on tiny “teeth” along the margins). Only Parmotrema has soralia like that. And the reticulum puts it in the old genus Rimelia particularly (P. reticulatum, P. subisidiosum and their rare chemotypes in your area).

You should also be paying attention to the color and rhizines on the underside. This one will be dark brown to black — which Flavoparmelia and several others are, too. But also it has especially long, occasionally irregularly forking rhizines, with a variably wide margin bare of rhizines. This bare margin will eventually help you diagnose Parmotrema in general, although the Rimelia aren’t a good place to start, since they often have rhizines going up very close to the margin. And Flavoparmelia will also often grow fast enough that it has a narrow bare margin. So ambiguous in this case. But there is a gestalt difference, and you will only acquire that by starting to pay attention to the character every time, even if it doesn’t help at first.

Created: 2017-05-03 10:00:05 CDT (-0400)
Last modified: 2017-05-03 10:46:43 CDT (-0400)
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