Banana slugs and salamanders in the moist duff. Mammal tracks on the muddy trail. Colorful mushroom caps. Bird nests perched in the skeleton branches of deciduous trees. These are sights of the season on a winter walk in the woods.
While many plants and animals have seasonal cycles and observing them is dependent on the time of year and climate, one group of organisms is reliably observable throughout the year. These species are long-living; their age measured in hundreds of years rather than tens of years. They are slow-developing; growing mere millimeters or centimeters per year. These are the lichens.
Lichens are an alliance between a fungus and a photosynthesizing partner. An analogy to remember this mutualism goes: “Alex Algae and Francis Fungus took a “lichen” (liking) to each other…”
Francis the fungus builds the house – providing shelter and protection. Alex the algae “cooks” – providing food through photosynthesis. In some species, the “cook” (i.e., photosynthesizing partner) is cyanobacteria instead of algae.
The playful phrase of Alex and Francis “lichen” one another has a supplement: “their relationship is sometimes on the rocks.” Since lichens don’t need nutrients from the soil, they grow on all sorts of surfaces: rocks, cliffs, boulders, bark, branches, soil, roofs, gravestones, wooden fences and decks, even on cars.
Lichens have a fascinating diversity of growth forms: dust, crust, scale, leaf, club, shrub and hair-like.
Their shapes elicit creative, descriptive common names: sea tar, bark barnacle, bull’s eye, lettuce lung, frog pelt, seaside kidney, tattered rag, beaded bone, fishnet, matchstick.
We recognized a few species around our home:
At the base of a redwood, a green powder coats the bark. This dust lichen comes in a variety of hues: whites, greens and grays.
The aging pear tree is covered with a leaf lichen, green-gray on the top and black on the underside with warty outgrowths on curled edges. We identified this species as waxpaper lichen.
An orange encrusting lichen decorates several rocks.
A family favorite is “old man’s beard.” This species grows in creamy avocado-green tufts. Clumps fallen onto the trail invite creative play as it makes a dwarf beard, fuzzy mustache or foresty tresses. Pull two sides apart to observe its elastic central cord.
Lichens are habitat for insects, a food source for herbivores and an essential nest-building material. They absorb pollutants, fix nitrogen from the atmosphere and help make soil.
Recognizing the importance of these organisms, a bill effective January 1, 2016 designates lace lichen Ramalina menziesii as the California State Lichen. Congratulations California on being the first state to name a lichen as a state symbol – truly something to be liking!