Field Notes: Learn About Lichen While the Wildflowers Sleep

By Joe Brehm, Environmental Education Director

If you enjoy complaining about winter, you may not want to read this, because I’m hoping to give you one fewer reason to dislike this time of year: lichen. Lichen is not one organism but two fused together; this symbiosis between algae and fungi gives lichens the ability to shine even in winter, giving nature lovers something to appreciate while the wildflowers sleep. Lichen is also famous for being the first “organism” to colonize bare rock after glaciers have receded from an area or some other disturbance wiped the land bare. They have no roots because they need nothing from the substrate on which they grow, and are otherwise completely self-sufficient. Marinating on the power of this partnership is timely as we continue navigating tough times and the strain and stress they bring.

According to the “lichen bible” (Lichens of North America by Irwin M. Brodo et al), which weighs roughly the same as a plump chihuahua, there are over 3,600 species of lichen in North America. The term “species” is interesting to apply to lichens because they are two organisms (that we know of – there may be others involved).

One of the most common lichen species in our forests is common greenshield (Flavoparmelia caperata), which clings to tree bark in beautiful flat green blobs. On a rainy winter day, greenshield lichen can make a forest glow green. I often wonder how much they photosynthesize on days like this, and how much refreshing oxygen the algae give us while our primary oxygen factories (deciduous trees) are dormant.

Another easy lichen genus to recognize is Usnea, the “beard lichens.” They are pale green, a common lichen color, and dangle from branches or stick out from tree trunks. They seem to especially enjoy living on big honey locust thorns. Usnea strigosa, or bushy beard lichen, is our most common species in this genus. The beard lichens are incredible for many reasons: 1) they are sensitive to particular types of air pollution and can therefore tell us something about the cleanliness of local air; 2) they can be used in salves and other herbal medicine with antibacterial properties (but apparently one-third or so of people are allergic to usnic acid, one of the prevalent compounds); 3) Northern Parulas make their nests out of big drapes of Usnea in the Southeastern part of their range. Citizen scientists have taken some great Usnea photos in our bioblitz of Wayne National Forest’s Athens Unit.

Learning about a new group of organisms like lichen can be overwhelming, so I would recommend this for beginners: focus on the Cladonia genus. Cladonia includes another very common species, common powderhorn (Cladonia coniocraea), which grows on dead logs and stumps. It also includes one of the most vibrantly tipped lichen species, british soldiers (Cladonia cristatella). British soldier lichen is topped with a glowing red “apothecia” (reproductive structure at the tip of its stalk), and can be found in incredible quantities at Hocking College’s Robbins Crossing on the wooden roof shingles. In all, our bioblitz has turned up 18 species of Cladonia.

Lastly, lichen viewing is a great activity for kids of virtually all ages. Lichen do not move, are ubiquitous (there are even two species that grow on sidewalks), and really fun to look at through a magnifying glass or microscope. Email me if you find that you take a lichen to this subject, or post your observations on iNaturalist. I look forward to seeing what you find out there.

(Field Notes is an occasional series that takes readers into local forests to learn about our natural world. Become a citizen scientist and join the more than 607 volunteers who have contributed close to 20,000 observations via iNaturalist to our “bioblitz” of the WNF’s Athens Unit, documenting roughly 3,904 species of plants, insects, fungi, mammals, birds, and more. You can join us by following instructions here.)