#lichenology

Cladonia prostrata

Resurrection lichen, dune cup lichen

Lichens are poikilohydric organisms, meaning that they cannot control how much water they take in or lose. When their environment is wet, they are wet. When their environment is dry, they are dry. Obviously water is necessary for photosynthesis, so lichens have a diversity of strategies to deal with this inherent stress, well adapted as they are to their climactic niches. One such strategy is visible here in C. prostrata: when moist, the long, deeply incised lobes unfurl, exposing the green algal photobiont in the upper surface to sunlight for photosynthesis, but when dry, the lobes curl and expose the pale underside, stopping photosynthesis while protecting the photobiont cells from photodamage. It basically allows the whole system to shut down until water is available again. This adaptation makes sense in context this lichen's particular survival strategy. The xeric sand pine scrub forests C. prostrata inhabits in Florida and Georgia are prone to fire, leaving the ground exposed to full sun and prone to drying out. By having a built in resistance to photodamage triggered by water loss, C. prostrata is able to survive in this stressful environment, and is in fact one of the first colonizers following a fire event! It helps to stabilize the soil and recharge it with nutrients, helping the system recover as a whole. Pretty cool, huh?

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Caloplaca pellodella (syn Caloplaca conglomerata) 

So a long time ago (not actually so long ago) people would look at lichens and be like "huh yeah, those pretty much look the same. They must be the same." And then some nerds were like "actually if you look at the really really closely and look at the chemicals they produce and stuff, you will notice they are actually different, but probably closely related." And then more nerds invented genetic analysis and were like "um actually, a lot of these lichens that don't look the same are actually the same, and a lot of these lichens that do look the same are not actually that closely related at all." And then because some other nerds invented computers and the internet, all the lichen nerds can argue about it from around the world, and we (also nerds) are stuck trying to clean up the messes made with naming these species before we had this all great new technology. Exhausting, really. So here I have a lichen that on one site is called Caloplaca pellodella synonymized with Callopisma conglomeratum, and on another is Caloplaca conglomerata synonymized with Caloplaca peludella, and look, I just gotta assume they are all talking about the same dude and he has just been named and renamed and typoed a thousand times over in the many years since someone first decided to classify him. And if any of y'all recall my good pal Jan Vondrák, he is currently working on disentangling the messy Teloschistaceae family and will probably end up reassigning/renaming it soon anyway. The Sisyphean reality of learning lichens.

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Seen on a walk today, thought you might appreciate :) South central TX. So much variety in one tiny branch!

Umbilicaria lyngei

Puckered rocktripe lichen

This umbilicate-foliose lichen grows in roundish, singular, up to 3.5 cm broad lobes attached to the substrate by a single, central holdfast. The upper surface is wrinkled-reticulate, dark-brown to black with pale pruina frosting the reticulate ridges, and the lower surface is black. It only rarely produces apothecia, which are black with gryrose discs. U. lyngei grows on rock in arctic and occasionally alpine North America.

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Adelolecia pilati

Lab work, field work, data analysis, writing, teaching, lichen identification, curating collections, bothering my coworkers. Since I am a PhD student, my day-to-day is all over the place. Currently I am preparing for a big lichen conference in Trieste, so I am spending all day perfecting my presentation and making sure all of my data is presented clearly and correctly.

Favorite lichen is tough. I have so many! But it'd probably have to be Rhizoplaca idahoensis, aka Idaho grouse pellet lichen: