Wilcox-Bushley Homestead
Wall Lichens
Lichens General Information
Lichens are not a single entity but a community of organisms coexisting in the same body. Members of this community vary but it usually consists of at least 4 major organisms: algae, fungi, bacteria and yeast. Imagine 4 different kinds of animals living in the same home! Over 19,000 lichen species have been discovered (Lücking et al., 2017). Among the 19,000 species, the fungi, algae, yeast, or bacteria can be in various combinations which contributes to their amazing diversity.
Lichens are unique in their capacity to tolerate extreme environmental conditions such as low temperatures, lack of water, and bright sunlight (Spribille et al. 2022). They can withstand conditions far more extreme than when either the fungal or algal partner exists on their own. Like a human community each partner contributes something that benefits the group. In lichens, the algae produce sugars through photosynthesis that feeds the fungi, and the fungi produces a protective layer that prevents the algae from drying out and dying (Spribille et al.2022). Fungi also protect the lichen from herbivory, UV radiation, and the fungi obtain nitrogen that it gives to the algae promoting its growth (Spribille et al. 2022). Bacteria and yeast seem to help keep the lichen healthy by providing some nutrients, protecting against stress, and they decompose some of the older lichen body parts (Aschenbrenner et al. 2016).
Lichen growth forms
Field guides rely on the shape and physical features of the lichen body for identification. The primary feature is the growth form. All lichens begin with the germination of a single spore and grow outwards in a circular pattern. For lichens adhering to a rock or tree this will be the most common shape you see, but the circular body or thallus does not describe the growth form. Growth form refers to how the lichen is attached to its substrate (rock, soil or tree) and whether the body of the lichen is two-dimensional (appearing flat) or three-dimensional (appearing bushy).
-
Crustose lichens are lichens where the outside edge of the lichen cannot be lifted from the rock or tree. To remove this lichen you would need to take a chip of the rock or tree bark. In this growth form the fungal partner grows between the mineral grains of the rock or within the layers of bark. These lichens look like paint that was splashed onto the rock surface or tree bark.
-
Foliose lichens are lichens have an outer edge that you can lift and peer underneath. The color and texture of the underside are important features used in identification. Undersides can be white, tan, or black. Texture can range from smooth to hairy with some having vein-like structures.
-
Fruticose lichens are three-dimensional lichens. They have upright reproductive structures that vary in shape and color and are sometimes bright red.
Here are photos and line drawings of the three major lichen growth forms.
​Image source https://ohioplants.org/lichenbiology/.

On the stone wall in front of the QR post there are numerous lichens. Use the magnifying lens on your iphone or phone camera to help you find and see the following 5 species. Do not touch or remove a portion of the lichen. Simply use your eyes to make observations.
Crustose lichens. These look like splashes of paint and cannot be removed from the rock.
-
Goldspeck. This lichen is bright yellow in color with yellow warty patches, separated by cracks. This species is common on granite rocks in sun exposed areas (Brodo et al. 2001).
-
Firedot. This lichen is also found on sunny exposed granite rocks but differs from Goldspeck in being orangish-red in color. ​
​​

Goldspeck

Firedot
Foliose Lichens – have an outer edge that can be lifted from the rock or bark.
-
Rough Speckled Shield. This lichen is found lower down on the wall, and is gray when dry or green when wet. It has broad lobes and the surface of the lichen has pores and small-peg like projects which are called isidia. See if you can see the pegs and pores using your magnifying lens on your camera. The pores help the lichen breathe and the pegs break off to make new copies of this lichen.
-
Cinder Lichen. This lichen is dark ash-gray in color with an outer edge of white. Compared to the Rough Speckled Shield above, this lichen has much narrower lobes on the edge of the lichen. The center of this lichen is highly textured and breaks up into distinct patches.

Rough Speckled Shield

Cinder Lichen
Foliose lichens. These are 3-dimensional, bushy or shrub like lichens that are more often found in soils.
​
-
Wand lichen. For this final species look in the sandy soil on the top of the stone wall. This lichen can be found in small patches. Look carefully and you may see it. It is recognizable by its mint green color of long upright stalks that have a brown spot on their tips. The brown spot is where the fungal partner of this lichen is reproducing by producing fungal spores.

Wand Lichen
​Thank you for participating in this exercise!I hope you have learned something about lichens and have enjoyed observing their unique characteristics.Lichens are both beautiful and fascinating.