Observation 198609: Physcia aipolia (Ehrh. ex Humb.) Fürnr.

When: 2015-01-22

Collection location: Carrizo Plain, San Luis Obispo Co., California, USA [Click for map]

35.3578° -120.0445° 613m

Who: J-Dar

No specimen available

Growing on Elm and likely other tree species.
Thallus upper surface greyish-white, doesn’t seem maculate (important for key), K+ yellow, mostly weakly pruinose, without ciliate hairs, pycnidia common. Lower surface corticate, pale, with sparse whitish rhizines.
Apothecia abundant, disc brown to black, margin +/- pruinose.
Soredia…possibly marginal on the lobe tips, I can’t quite tell and couldn’t get a photo. The very tip of some lobes darken and seem to have soredia.
Isidia…probably not, but I’m not experienced enough to say for sure.

P. aipolia seems the best fit, except thallus should be white-maculate, and no soredia should be present.


K+Y thallus. 40×.
Apothecia. 40x

Proposed Names

28% (1)
Used references: Nash VI, Brodo et al., MO, www.lichenportal.org
Based on chemical features: K+Y

Please login to propose your own names and vote on existing names.

Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Agreed, P. aipolia is a good candidate
By: Jason Hollinger (jason)
2015-02-13 11:22:42 CST (-0500)

It is somewhat of a concern that the apothecia have almost no pruina, and I don’t see conspicuous white mottling on the thallus surface. The overall shape and feel is wrong. But… it’s a variable species! And presumably growing close to the edge of its range down there [EDIT: no, it goes all the way into the tropics.]

With that many apothecia, it’s probably not sorediate. What you’re seeing is probably the thallus breaking down a bit from stress or mechanical disturbance(?)

Here are the options from Sonoran Flora:

P. biziana – medulla K-, surface strongly and conspicuously pruinose
P. stellaris – medulla K-, surface generally not pruinose or mottled, lobes < 1 mm wide
P. aipolia – medulla K+y, surface strongly mottled, sometimes ~pruinose, lobes > 1 mm wide

(Weeding out ones on rock, or only known from Sinaloa(!) or otherwise wrong.)

Created: 2015-02-12 20:00:08 CST (-0500)
Last modified: 2015-05-25 14:00:01 CDT (-0400)
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