Observation 11631: Cladonia P. Browne
When: 2008-09-27
No herbarium specimen

Notes: My knowledge of lichens is woefully lacking. I would appreciate any suggestions for a budding lichenologist on a good book for lichens in the PNW. This specimen was photographed on a lava rock that I use as a decorative planter in front of my home in SE Portland. It is in the center of the photo (to prevent confusion with the other lichens n the same photo), and has a distinctive post horn shape, arrising from a grayish-white to greenish-gray base. Total height of what I presume is a fruiting structure? is perhaps 1 cm.

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Used references: Brodo, Lichens of North America

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From Pixie-cups to Russula
By: Jason Hollinger (jason)
2008-09-27 22:45:33 CDT (-0500)

Lichen taxonomy traditionally (and for the forseeable future, though see the set of Evansia articles Trevor Goward is currently writing) strictly follows the fungus. This makes some sense, as the thallus is by far dominated (in volume and mass) by the fungus, with the algae (and/or cyanobacteria) forming only a single thin layer (and/or the occasional cephalodia).

And as far as lichenologists know, a given lichenized fungus only pairs up with a single species or at most group of closely-related species of algae. (Again, there are exceptions, such as Pseudocypellaria anomala which can pair up with either a green alga or a cyanobacteria, producing completely different thalli, one of which used to be called Dendriscocaulon until we learned better.)

I believe it has been demonstrated that multiple species of lichenized fungus can use the same species of algae interchangeably, but the converse appears not to occur.

As for variability, I cannot comment on Russula, but in the case of Cladonia, it is almost certainly a result of microclimate pressures. There is a great deal of work being done in this area. Lichens are extremely sensitive to moisture, light, ventillation, substrate chemistry, among many other environmental conditions — they have to be, since the range in which both alga and fungus can simultaneously metabolize is very narrow.

Xanthoria will be brilliant danger-orange on top of a limb, and pale yellowish-green on the underside of the same limb; sometimes the very same thallus will exhibit this entire range of variation if it is sufficiently large. Other lichens will produce different fruiting bodies depending on the amount of sunlight versus moisture, sometimes changing mid-life if, say, it suddenly finds itself at the edge of a massive clearcut. At any rate, Cladonia seems to be particularly susceptible.

I would love to see some similar experiments done on Russula, or any other mycorhizal macrofungi, for that matter. But it seems to me there are some very significant difficulties — lichens at least are there for all the world to see all year round, and in many cases are extremely abundant — hundreds if not thousands on the same tree, on every tree, compared to, for example, Laetiporus gilbertsonii occurring empirically on only one out of 4-5 carob trees in Pasadena. How does one achieve statistical significance in circumstances like this?

Lichen taxonomy
By: Paul Derbyshire (Twizzler)
2008-09-27 22:03:45 CDT (-0500)

How, exactly, is lichen taxonomy done anyway? I should think that there would actually be a two-dimensional structure because the species of alga and species of fungus might vary separately. I expect there will be restrictions, some pairs not being compatible, but is the compatibility requirement typically so strict, or the character of a lichen typically so dependent on only one of its two components, as to make the identity of one component serve well enough as the identity of the whole lichen?

Of course, the “highly variable” thing might reflect classification of lichens based on only one component, with the variation coming from different identities of the other.

With mycorrhizal fungi, one wonders if the identity of the plant partner influences morphology of the fungal fruit-bodies somehow, at least for certain kinds of fungi. It would explain the particularly super-variable Russulas if they acquired some pigment molecules from their partners and then concentrated them into their mushroom caps! Finding out exactly what sorts of traffic cross the junction and in which directions, as well as how much variability is genetic and how much is environmental, would seem necessary there. Being parasitized by other plants, such as Indian paintbrush, might have its effects. If this mechanism occurs and is important, though, there should be some correlation between variability of mushrooms and (lack of) host specificity, and between particular variations and the presence of particular host plants in the neighborhood too.

The true number of Russula species could turn out to be quite low, in that case, with only a handful of red-capped species perhaps. Genetic tests or seeing which pairs will interbreed could tell the tale.

Other mycorrhizal genera could be affected this way, and all fungi could be affected by the presence or absence of compounds in their soil or wood substrate. Not just pigmentation variations, but variations in toxicity/edibility, odor, taste, and other kinds of variations could come from the environment in this manner. It would explain why some mushrooms are labeled as poisonous or not on a regional basis, or as severely poisonous versus merely poisonous likewise.

By: Jason Hollinger (jason)
2008-09-27 19:14:35 CDT (-0500)

Possibly Cladonia chlorophaea or at least related. There are a bunch of closely-related cup-shaped Cladonia, distinguished by amount and texture of granules/powder on the stalk and in the cup, presense of lobules, and chemistry: KC for usnic acid (K=KOH followed by C=bleach turns weak golden in presence of usnic acid) and PPD for various acids (hard to get). Besides, I am secretly convinced no one really understands this group yet.

A good book for your area is Bruce McCune’s Macrolichens of the Pacific Northwest. Brodo’s excellent (but ponderous) Lichens of North America is the only game in town for crustose species as far as I know.

(It’s likely that 11633 is the same thing — all these species show tremendous variation, even within a single population, depending on microclimatic conditions.)

Created: 2008-09-27 17:07:49 CDT (-0500)
Last modified: 2012-11-27 16:36:05 CST (-0600)
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