Observation 74961: Cladonia petrophila R.C. Harris
When: 2011-08-29
Who: zaca
No herbarium specimen

Notes: Another sterile Cladonia sp. living among mosses and other cladonia species, under the shadow of a fence in the field. There were several cushions like the one in the first photo (measuring 7.5 cm wide, so that the squamules are of 2-3 mm wide) all of them steriles. The C+ green reaction lead me to C. strepsilis, according to the key presented in Lendemer and Hodkinson. On the other hand, in lastdragon this C+ green (said to be emerald) reaction is also mentioned and the color of the squamules is described as “typically pale bronze-green above, white beneath”, which I think is the case of this specimen (see the left-center of the first photo). However, none of the above references refers the K+ yellow-red-brown reaction, which I think reveals the presence of fumarprotocetraric acid. Therefore, I’m not secure that it is C. strepsilis and maybe is another usually sterile species.

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Did I introduce some confusion? No doubt…
By: Jason Hollinger (jason)
2011-08-31 16:27:32 CDT (-0500)

1: “Cladonia petrophila is restricted to shaded non-calcareous boulders and rock outcrops”

2: “Cladonia petrophila is known only from eastern North America where it is widely distributed in the Appalachian Mountains, Piedmont, and Ozark Ecoregion…”

Ozarks contain both calcareous (limestone and dolomite layers) and non-calcareous (sandstone). Southern Appalachians are almost exclusively siliceous (granitic and hard sandstone). The Cumberland plateau, between the two, has much calcareous strata (but also circumneutral strata). Georgia and parts of western North Carolina (overlapping very southern tip of Appalachians) have lots of limestone, too, but again granite outcrops are present even in these areas. Piedmont east of the Appalachians is entirely granitic, I believe.

So my interpretation of both is that it is only known to grow on non-calcareous rock.

Thanks, Jason, for the very instructive notes about this observation.
By: zaca
2011-08-31 15:31:49 CDT (-0500)

However, there there is something that I don’t understand:
Lendemer & Hodkinson 2009 about the ecology of C. petrophila says:
“As discussed by Harris (1992), Cladonia petrophila is restricted to shaded non-calcareous boulders and rock outcrops in intact hardwood forests, often near streams, streambeds, or habitats with high humidity. In particularly humid localities, the species can also occur on the roots and bases of hardwood trees; however, typical saxicolous thalli are always present in the immediate vicinity.”
On the other hand, about the distribution it is said that:
“Cladonia petrophila is known only from eastern North America where it is widely
distributed in the Appalachian Mountains, Piedmont, and Ozark Ecoregion. A chemotype lacking fumarprotocetraric is restricted to the southern Appalachian Mountains (see specimens cited below) and outlying granite outcrops in the Piedmont of the southeastern United States.”
So, what is the ecology of Ozack Ecoregion? Calcareous or non-calcareous?
In my opinion only the chemotype lacking fumarprotocetraric acid lives in outlying granite outcrops in the Piedmont of the southeastern United States, while the other chemotype can live in calcareous habitats. Can you interpret those sentences otherwise?

I made the same mistake with C+ green
By: Jason Hollinger (jason)
2011-08-31 14:36:21 CDT (-0500)

Once you see the real thing, though, you’ll kick yourself. It’s very distinctive. Problem is C will tend to dissolve and/or make the cortex and medulla transparent, allowing the green algae show through, and can – especially in thin squamules – appear to be C+ green. The C and KC test on true strepsilin is highly satisfying, usually almost instantaneous, but occasionally taking 2-3 seconds to develop, and distinctly changes the hue (as opposed to merely intensifying the green that’s already present).

I have no experience with these sterile Cladonia on limestone. Lendemer & Hodkinson 2009 claim C. petrophila only occurs on non-calcareous rock, and it is well-documented from areas with abundant limestone outcrops (e.g., the Ozarks), so that observation is very significant. If it’s common in an area with calcareous rock, but hasn’t been observed to occur on them, then it probably really doesn’t.

It’s certainly worth keeping one other option open: you could well have an undescribed species. It is apparently not uncommon that a locally-abundant species will have been collected extensively and lumped erroneously in with a better-known species just because the field-worker(s) in question didn’t have time or resources to make a rigorous study of the literature and type specimens and to do all the chemistry, etc. required to confirm that their odd-looking material really is different. Note that C. petrophila, as common as it is, wasn’t described until 1992; and C. stipitata not until 2009 (very common on exposed outcrops in the southern Appalachians).

(Incidentally, look at photos 4 and 6 on plate 3 in L & H 2009 — those are excellent examples of pycnidia and apothecia on petrophila. Pycnidia of apodocarpa and the symphicarpia/polycarpoides/polycarpia group look the same.)

You’re right,
By: zaca
2011-08-31 14:15:03 CDT (-0500)

it seems that everything matches the description of C. petrophila, except the reaction C + green (weak), I probably misinterpreted.
The specimen was growing on the thin soil over rock, protected by the fence at a distance of 70cm to 1 meter. The rock at this place it is mainly calcareous.

It matches C. petrophila well
By: Jason Hollinger (jason)
2011-08-31 12:44:25 CDT (-0500)

I hadn’t noticed the scale you quote in the notes; this is the correct size and habit and shape. Was it growing on rock or thin soil over rock? It looks like it was. If sufficiently sheltered by the fence post, this might well be suitable habitat for petrophila.

Another to consider is C. cariosa, although its squamules – though small – tend to be less branched and less curled (and it usually has at least one or two podetia somewhere. It’s also typically more northern, and should have atranorin, not fumarprotocetraric (K+y instead of K+red/brown).

Thanks, Jason, for the clarifications.
By: zaca
2011-08-31 12:02:03 CDT (-0500)

I doubt this is again C. apodocarpa, since squamules are about 10 times smaller than the specimen in the Observation MO74960. I will Investigate the other possibilities.

“Emerald” is very distinctive for C. strepsilis
By: Jason Hollinger (jason)
2011-08-30 18:59:18 CDT (-0500)

It has a distinctive bluish cast to it, and it affects both the white and green surfaces of the squamules. Here’s the only photo I have of the reaction (from material I saw at a workshop in Georgia, USA):


Also, C. strepsilis tends to form round mounds, not large colonies like this. The colony form is common for C. apodocarpa, C. polycarpoides, C. symphicarpia, and kin, instead.

Yours looks just like C. apodocarpa or C. polycarpoides, but the chemistry seems to be off. (The former has atranorin and fumarprotocetraric, so should be distinctly K+y at least a first as seen on the underside; the latter should definitely eventually turn K+r.) A possibility worth considering is C. petrophila, a species which I thought was endemic to eastern US, but it has either just fumarprotocetraric acid or nothing; it’s essentially a smaller branchier version of apodocarpa, and is found in woodlands.

Created: 2011-08-30 18:09:32 CDT (-0500)
Last modified: 2011-09-02 06:30:11 CDT (-0500)
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