Lacy Life in Lichens

  Thursday was "Honor-an-Invertebrate Day" over
  at Life Photo Meme. You oughta pop over
  there and check out the adorable little
  octopod they found!

Meanwhile, here at Foothills Fancies, I'm just catching up with the previous week's challenge: Lacy... Something alive, and lacy. We're going to try it with lichens. First up is this specimen of Usnea cavernosa, in the group sometimes called "beard lichens." The genus Usnea is characterized by, among other things, the presence of usnic acid, a lichen compound that gives it a distinct coloration. Click to enlarge photos for a better view.

Beard lichens are fruticose, that is, 3-dimensional or, literally, "shrubby." This species is long and pendent, but look for shorter ones on tree trunks. Here in the Rockies, they are very common on conifer bark, for example. U. cavernosa is, in fact, the only pendulous Usnea I've ever seen or am likely to see, unless I get to the Cascades or coastal northwest, where the others live. You can see more long Usneas at Lichen.com, in the portrait gallery. That site is, by the way, a terrific reference for lichen information and photo-IDs. (The image above is a direct scan of the specimen, not a photo.)

This cutie is another favorite of mine, though I haven't figured out the species and don't expect to. (My best guess is C. squamosa.) I'm happy knowing that it's a species of Cladonia, and in this case, lacy is in the leafy squamules at the base of the critter. Cladonias are two-part lichens, often with upright structures called podetia. In this one, a slight suggestion of podetia can be seen, though those too are covered with squamules.

Lastly, a more typical lichen (or two) of the foliose growth form, Parmelia sulcata, lower right and center in this photo. Very common on moist rocks, where it often consorts with mosses, P. sulcata is steely gray when dry, somewhat more blue-green when damp, as here. The smaller frilly gray lichen around its upper edge is most likely a species of Physcia or perhaps Parmeliopsis.


Few lichens have real "by the people" common names, though specialists have been making up some just to make it easier for the rest of us to deal with these fascinating beings. Parmelia sulcata, for example, may be known as "hammered shield lichen." If you enlarge the photo, you'll see the hammer marks that suggest that name. The genus Parmelia in general is called shield lichens, but sometimes these new common names can be more cumbersome than the Latin binomials!

Who could resist these guys? With their variety of form, color, texture, and habitat, and more than 17,000 species to keep us guessing, lichens are a great way to make it through long winter months when other "plants" are dormant.