Dark Forests of the San Juan Mountains

Lichen covered branch in San Juan County, CO.

One of my oldest nature memories was my grandparents taking me on a walk around Brainard Lake in the mountains of Boulder County. I’m not even sure how old I was. But I was struck by the tall pines, the smell of the forest, and the moss-covered trees. Since then I haven’t lost a love for the subalpine forest, but I have learned that the pines were Englemann Spruce and the “moss” were lichens, specifically those in the genus Usnea.

Usnea cavernosaMineral County, CO.

A particularly wonderful forest I happened upon was along HWY 550 north of Durango along Cascade Creek. I had actually been hoping to find a particular species of lichen on the trip–Usnea cavernosa. As I understand it, it is the largest Usnea in the state, and therefore rather easy to identify in a difficult genus. Check out (photo two) the distinctive pits on the branches that give this species its specific epithet and separate it from similar species elsewhere in North America.

Many people when first seeing these organisms assume they are Spanish Moss, familiar if you have travelled in the Southeast. Spanish Moss, like lichens, suffers from a colloquial description as moss, however it’s actually a flowering plant. The strands of Usnea cavernosa can purportedly grow up to 2 feet long! It was the first time I’ve seen large stands1 in the state.

Upon closer look this was not the only species growing in the area. In fact I found at least four species of pendant fructicose lichens in the image at the top of the page. Others are:

Evernia divaricata

This lichen appears to be common at a certain elevation in CO if the area gets enough shade and water. All Usnea species have round branches, the flat branches of Evernia should easily separate this genus. Well, among pendant lichens with that off-color green that betrays the presence of usnic acid.

Ramalina sinensis

This was a surprise. The genus Ramalina is mostly coastal. On my last trips to California and North Carolina, oaks were covered in related lichens. I had no clue they occurred in CO. The wide branches (often very broad) with ridges should be enough to confirm an ID in CO. For bonus points the underside should have areas of breaks in the thallus between the ridges where the medulla is visible, called pseudocyphellae. This photo is the top side so the mark is not visible. Herbarium records show a concentration of the species in the San Juan Mountains but look for it in elsewhere and perhaps other members of the genus.

Bryoria sp. – As far as I can tell this appear to be Bryoria fuscescens but the taxonomy appears to be in flux and many of the keys are confusing to say the least!

Lichens often make you have to appreciate some, well, less aesthetically pleasing organisms. Bryoria sure fit that bill. These dark lichens are pretty unmistakable in CO. They have a particular fondness for Douglas-fir.

The final species I found was Usnea perplexans. Feel free to follow the link. We have covered Usnea before! This species appears to be the most common species in the state, but I wonder if I am applying the keys correctly. Our previous post mentions U. subfloridana which also occurs in the state, and looks very much like U. perplexans. My conclusion is that perplexans is a perfect name for the situation. I’ll be sure to post if I work it out!

1Riddle me this, but everywhere I have read seems to talk about the genus like they are trees. They grow in “stands” and have branches. Can you think of another organism that a group is described as a stand?

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