Observation 87563: Leptogium platynum (Tuck.) Herre
When: 2012-02-08
Who: Byrain
No herbarium specimen

Notes: Growing on moss on a river bank, this part of the river is usually full of water, but not this year.

Proposed Names

28% (1)
Recognized by sight
61% (2)
Eye3 Eyes3
Recognized by sight: lobules on surface and margins
56% (1)
Recognized by sight: lobules on margin and surface (see comments)

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Eye3 = Observer’s choice
Eyes3 = Current consensus

Comments

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Description of L. polycarpum
By: Jason Hollinger (jason)
2012-02-11 03:11:46 CST (-0500)

From Lichens of N. Amer. (Brodo et al 2001): “This is a rather rare, western American endemic, much like L. gelatinosum but the asci consistently contain only 4 spores and the apothecia remain halk-sunken at maturity. It also resembles L. californicum, but in that species, the apothecia are not as crowded, and they are not sunken; their asci contain 8 spores. L. californicum grows mainly on mossy rocks and soil. See also L. platynum… [L. polycarpum grows] on the bark of deciduous trees in coastal forests.”

L. gelatinosum
By: Byrain
2012-02-10 23:17:08 CST (-0500)

Compare this – http://www.sharnoffphotos.com/...
With this – http://www.sharnoffphotos.com/... & http://www.irishlichens.ie/pages-lichen/l-221.html & http://www.lichens.lastdragon.org/Leptogium_gelatinosum.html.

I would think L. gelatinosum looks a bit less robust as CNALH says.

And I found the picture of L. polycarpum, what I was unable to find is a description.

Sharnoff should have one
By: Jason Hollinger (jason)
2012-02-09 13:54:49 CST (-0500)

(of L. polycarpum) There’s a photo in my copy of Lichens of North America, and those are all now on Sharnoff’s website.

I originally assumed it was Collema just based on some undefinable overall look and feel. But predictably I was dead wrong. Another difference between platynum and californicum:

platynum: lobe tips glossy and strongly downturned, upper surface sharply wrinkled, coastal

californicum: lobes rarely both glossy and strongly downturned, upper surface smooth or in part weakly wrinkled, dry areas inland

It would probably help to see a photo when it’s dry. It’s hard to see texture and gloss when moist. Wrinkles often disappear completely when full of water.

[edit: I hadn’t considered L. gelatinosum. It does look promising. It has smoother surface than platynum, key differences are:

platynum: lobe tips strongly downturned, mostly rounded in outline, coastal
gelatinosum: lobe tips often upturned or at least not strongly downturned, margins with rounded lobules oriented in a single plane, apothecia frequent]

I think you’re right
By: Byrain
2012-02-09 04:34:20 CST (-0500)

I just looked at every picture and read every description I could find, both of the Collema spp mentioned really don’t look like this at all to me.
See http://www.stridvall.se/lichens/gallery/Collema?page=1

As for the Leptogium, CNALH claims, “Leptogium platynum is robuster and thicker than L. californicum or L. gelatinosum” which appears true with this specimen. Though I am not finding many pictures of L. polycarpum, much less a description, do you know where I could find one?

I’m hopeless with Collema and Leptogium
By: Jason Hollinger (jason)
2012-02-09 03:13:28 CST (-0500)

It’s hard to tell with these blackish ones. Look at C. cristatum maybe or C. flaccidum? Or in Leptogium, maybe L. platynum or L. polycarpum? Oh and there’s something called L. californicum, which is similar to L. platynum. Nothing really seems to fit. But then, this is an amazingly well-developed specimen. It might just be “going crazy”…

I’m leaning toward L. platynum right now. It’s described as having flattened overlapping lobules on the surface, and the photos on Sharnoff’s site aren’t so far off.

Created: 2012-02-09 02:37:47 CST (-0500)
Last modified: 2012-02-09 13:59:25 CST (-0500)
Viewed: 57 times, last viewed: 2014-05-28 09:32:57 CDT (-0400)
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