Observation 44452: Usnea trichodea Ach.
When: 2009-12-01
Herbarium specimen reported

Notes: This is abundant in hemlocks in the bottom of deep valleys of Cataloochee area. It has a very yellowish, fine, smooth look to it. It fails to key out in “Lichens of North America”, but it keys out very convincingly in “Macrolichens of New England” (Hinds & Hinds). The key characters are the conspicuous articulated, or bone-like, joints, and the K+ yellow to red reaction. The latter spot test turned bright red instead of deep blood red. This reaction is more typical of norstictic acid than salazinic. Also, U. merrillii is not recorded for the park. But the only thing on the park checklist that comes close is U. trichodea which also has the bone-like joint cracks, however this species has different chemistry (K+ yellow, KC+ pink/orange, CK+ orange/red).

Update on 20100517: James Lendemer determined this to be U. trichodea apparently despite the chemistry. I have no choice but to trust him on this, but sure wish I could hear the reasoning behind it…

Images

83618
83619
83620
arrow indicates “regeneration bead”
83621
K+ yellow to red spot test

Proposed Names

58% (1)
Recognized by sight: conspicuous joints with “regeneration beads”
Used references: Hind & Hinds 2007
Based on chemical features: K+ yellow turning bright red
87% (1)
Eye3 Eyes3
Used references: det: James Lendemer, specimen at NY

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Eye3 = Observer’s choice
Eyes3 = Current consensus

Comments

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Maybe neither? Check central cord.
By: James M (macrolichens)
2010-09-13 14:00:40 PDT (-0700)

Central cord of U. Trichodea is reddish pigmented
Central cord of U. merrillii with scattered reddish pigmentation
If you have a microscope: 1) Fistulinae in the central cord of U. merrilli packed with crystals. 2) Fistulinae in the central cord of U. trichodea lack crystals.
CMA measurements do not seem to be of much help with these two species (about a 14% chance of misidentification at point of Least overlap when using discriminate function analysis)
Varius combinations of usnic acid, salazinic acid, constictic acid & diffractaic acid have been noted in TLC analysis of U. trichodea specimens(n = 100)But no norstictic acid.

Created: 2010-04-19 15:37:37 PDT (-0700)
Last modified: 2010-05-18 08:18:55 PDT (-0700)
Viewed: 93 times, last viewed: 2016-10-19 08:29:47 PDT (-0700)
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