Observation 53513: Cladonia pyxidata (L.) Hoffm.

These are short, cup-forming Cladonia with round, peltate scales lining the inside of the cups, so there are two species to consider (characterizations from McCune and Geiser, 2009, pp.70 and 95):
Cladonia pocillum (“primary squamules closely packed or subcontinuous, rosette-forming … drier sites”)
Cladonia pyxidata (“primary squamules separate, not closely packed or forming rosettes … mesic sites”)

CNALH range maps show both of these species in the Rocky Mountain national parks of southern Alberta. The CNALH Cladonia pocillum gallery makes the interesting observation that “The specific status of C. pocillum is actually in doubt, because it is suspected to be only a sturdy morph of the C. pyxidata complex, that grows on base-rich soils and accumulates calcium oxalate. It may be an ecotype.”

Photos by Sharnoff and here on MO illustrate these taxa:
Cladonia pocillum: Sharnoff’s Cladonia pocillum gallery; MO Observation 18585; MO Observation 18591
Cladonia pyxidata: Sharnoff’s Cladonia pyxidata gallery; MO Observation 21651

The site is very near treeline, just above Highwood Pass, which at 2,200m is the highest point reached by a road in Alberta, and surely counts as “more mesic.” The primary squamules are not the broad, confluent, rosette-forming affairs we see in most of the photos of Cladonia pocillum, so I think these photos represent Cladonia pyxidata.

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Used references: McCune and Geiser, 2009, pp.70 and 95

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These confused me, too
By: Jason Hollinger (jason)
2010-09-27 17:38:23 PDT (-0700)

I collected many samples of these things in Alberta, apparently spanning the whole continuum from classic C. pyxidata to “obvious” C. pocillum. I ended throwing my hands up in despair! I’m hoping Trevor Goward can enlighten me when I see him next month.

Created: 2010-09-22 15:13:36 PDT (-0700)
Last modified: 2010-09-22 15:37:59 PDT (-0700)
Viewed: 157 times, last viewed: 2018-04-11 21:15:45 PDT (-0700)
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