Our abstract-looking photo this month features a close-up of a portion of a rock covered with lichens and moss. Lots of other boulders in Saginaw Forest (3900 W. Liberty Rd.) are similarly covered, and the silvery lichens and emerald green mosses make portions of the forest floor glow.
Spring is a great time to look for mosses and lichens. According to Tony Reznicek, a curator at the University of Michigan Herbarium, mosses, although they may have been frozen in the winter, do not go through a dormant stage like a deciduous tree. Instead, they are good to grow as soon as they thaw. Tim James, another curator at the Herbarium, told us that lichens also just hang around in the winter and resume their normal lives once the weather warms up.
Lichens and mosses, while they sometimes share a rock or other surface, are totally different. Each lichen consists of at least two species, typically one or two species of fungi and one to three species of algae; in some lichen combinations, bacteria join or replace the fungus.
Lichens are examples of biological mutualism. Our layman’s translation is that lichens are one of those marriages made in biological heaven, where each of the participants contributes to the well-being of the others to form a harmonious whole. In this case, the fungus contributes the ability to retain water and forms a structure for the algae or bacteria to grow on. The algae or bacteria, for their part, use photosynthesis from sunlight to produce food for themselves and the fungus.
Mosses, on the other hand, are plants that have stems and leaves. What they don’t have are flowers or seeds, reproducing by means of spores instead.
In our local environments, according to Reznicek, mosses form a “substrate nursery” for seeds of flowering plants, providing both moisture and a surface for seeds to cling to. They also hold in water and help prevent soil erosion.
Whether you look in a garden or graveyard, in a park or on a pillar or post, or even on a shady damp wall, you may find moss. Lichens, according to James, can be found almost everywhere, although they may be small and require a close look. While mosses prefer moisture and shade, lichens are more sun-loving and can stand more dryness.
Reznicek suggests looking for mosses on north- or east-facing slopes or ravines that are steep enough so that leaves don’t gather. One such spot is in Argo Park, down toward the Huron River from the boardwalk along Barton Dr. just east of the M-14 bridge. We also had good luck spotting them at Saginaw Forest.
For a guide to local lichens and mosses, Pat Rogers, a collection manager at the Herbarium, recommends Julie Jones Medlin’s Michigan Lichens (out of print, but available at the AADL) and Janice Glime’s The Elfin World of Mosses and Liverworts of Michigan’s Upper Peninsula and Isle Royale. Rogers also noted that the Herbarium’s collection of Michigan mosses has been documented in an online database, and soon its lichen collection will be as well.
