April Tree-following—about that Lichen

Several days ago, we headed off to visit the trees I'm following this year. It was a warmish sunny day that felt like spring, finally. And it was very windy, as is often the case in spring.

The two Rocky Mountain Junipers were looking good. The midday light showed their difference in color. The darker tree is the one with "berries" (fleshy cones) on the leeward side. Almost all are yellow. Two seasons are needed for berries to mature. Last year must have been a good one, given all the yellow berries. If the experts are right, this year we will watch them turn blue black.

With so much wind, sharp closeup photos were impossible.

Last month I included photos of a lichen that is really common on the ground in this area. Several readers responded with id suggestions and information—thanks!

Mystery lichen in March.

You probably know that lichens are symbiotic beings. That puts you are ahead of the great botanist Carl Linnaeus, who considered them “poor peasants of the plant world”. Wrong, Carl! But of course that was nearly three centuries ago. We've since figured out that lichens are not plants but rather composite organisms—a fungus and an alga or a cyanobacterium living tightly integrated lives. See Wikipedia's very interesting lichen page about their ecology, how they grow, their long evolutionary history, and the problems they cause when we try to classify them :) For a more philosophical view, try Lichens and the Meaning of Life.

The lichen that is so common in the eastern part of the Laramie Basin is ...  (fanfare) ... Tumbleweed Lichen! That is sooooo perfect for our windy world. Tumbleweed Lichen is a vagrant lichen, also an apt name. Instead of attaching to a substrate—rock, log, fence, etc.—it hugs the ground until wind sends it traveling again.

Our Tumbleweed Lichen is probably Xanthoparmelia camtschadalis or maybe X. chlorochroa. Seven Xanthoparmelia species occur in Wyoming and they're hard to tell apart. X. camtschadalis is common east of the continental divide, which is where Laramie is located.

The junipers I'm following grow in dry sagebrush grassland on thin rocky soil developed on limestone (at or not far below the surface)—harsh conditions, but Tumbleweed Lichen obviously does well here. Coverage ranges from small patches here and there to extensive ground cover, especially on the windward side of sagebrush, grass, and other plants.

Note penny on right, for scale.

Pale green patches at base of plants (lower right to mid left) are lichens whose tumbling was stopped by sagebrush and grass.

Tumbleweed Lichen and Pricklypear Cactus.

In some places, Tumbleweed Lichen dominates the ground cover.

Last month I predicted Easter Daisies (Townsendia) would be blooming now, but I was wrong. The daisies know better. In fact, we woke up to snow this morning.

Easter Daisies wisely waiting for spring.

Sources

Thanks to Judy vA for the articles included here. She met these vagrant lichens in her yard when she lived in Laramie. Thanks also to Jozien and Lysandra for id advice via iNaturalist.

Perry, Tyrell. 2018 (Winter). "What are Lichens?"  Barnyards and Backyards. U. Wyoming, College of Agriculture. PDF

Popova, Maria. 2023 (Mar 25) Lichens and the Meaning of Life. The Marginalian.