Rich Hyerczyk and I sat down at a picnic table in Harms Woods to discuss lichens. He had an assortment of books, information sheets, hand lenses, and bottles of calcium hypochlorite and potassium hydroxide to help with species identification. I thought, OK, here is all the equipment, where are the lichens? He pointed at the tabletop. The dark weathering wood was coated with a film of pale green.
"This is Lecanora," he said, naming a genus of crustose lichen. "I can't be sure of the species." Looking through a hand lens, I could see tiny saucerlike structures scattered over the green surface of the lichen. These are apothecia, reproductive structures that send out spores ready to create a new generation of lichens--possibly on this tabletop, possibly on another table, possibly on the rail fence at the edge of the picnic ground, possibly on a fallen log.
I had seen that greenish film before on wood left outdoors, but I had always thought it was just an alga or perhaps a moss. When I lived in Seattle we had railroad ties in our backyard as landscaping elements, and they were covered with the stuff. Lecanora gets slippery when it's wet, and one of my most vivid memories of my time in the great northwest was a fall I took on a soggy railroad tie that led to arthroscopic knee surgery--which is my absolute most vivid memory of the northwest.
The rail fence at Harms Woods harbors several kinds of lichens, and it is a major reason why the lichen flora of Harms Woods is richer than that at any of the other preserves along the North Branch of the Chicago River. We know this because Hyerczyk has surveyed every one of these preserves in search of lichens.
You have seen them as green films on wood or yellow patches on tree bark or gray disks on rocks. In areas recently uncovered by melting glaciers they are the first colonizers of bare rock. In more stable circumstances lichens specialize in particular substrates. Corticolous species live on tree bark; lignicolous species live on wood--including picnic tables--saxicolous species live on rock or concrete, and terricolous species live on soils. And, according to Rich Hyerczyk, species that live on reeds are called reedicolous. A little lichen humor.
Lichens are a perfect argument against reductionism. They are wholes that are much more than--and much different from--the sum of their parts. The parts are a fungus and an alga. Algae are green plants. They contain chlorophyll. They make their food by capturing the energy of sunlight and converting it to sugar. Fungi do not make their own food. In the great ecological scheme of things they are usually decomposers who make a living by feeding on organic matter both living and dead. They help reduce wood and other complex chemicals to their constituent elements, returning them to the ecosystem and making them available once again to living things.
In lichens the fungi provide a structure, a protected environment for the algal cells. If you were to slice open the pale gray body--called a thallus--of Physcia millegrana, a common species growing on tree bark in our area, you would find that the upper and lower layers are fungi. Between these upper and lower cortices is the sheltered environment where the algae live.
It is possible to grow the algae and the fungi of lichens separately in laboratory conditions. But the fungi will not assume their lichenous form without the algae. Living by themselves they grow as shapeless blobs, and they do not reproduce.
Out in nature they reproduce in a couple of different ways, none of them involving sex. The spores in those saucer-shaped apothecia I saw on the Lecanora are created vegetatively by the single parent plant. Other forms of vegetative reproduction happen too, but to a considerable extent, to quote How to Know the Lichens by Mason E. Hale, "the reproduction of lichens in nature is a mystery. Sexual reproduction in which spores germinate and recombine with algae is theoretically possible but no one has been able to follow these steps in nature."
It strikes me that Hale's words provide all the reason anyone would need for getting interested in lichens. Here is a group of organisms familiar enough to grow on picnic tables and fence posts and still so mysterious that we don't really know the details of how they reproduce.
A thought rather like that seems to have struck Rich Hyerczyk a few years ago when he took a course in lichens in pursuit of a degree in botany. He already had a degree that prepared him for a career in the computer-assisted design of machine parts. The botany courses were purely for the love of it, a love stoked by Hyerczyk's involvement in ecological restoration at the Palos forest preserves.
Restoration work is often an open-ended kind of thing. You start out pulling a few weeds, and the next thing you know you're studying for finals in lichenology. Early this year Hyerczyk completed two major reports: one on the lichen flora of the North Branch preserves, and the other on the lichen flora of the Palos and Sag Valley preserves. He has also done extensive fieldwork in Putnam County, which is along the Illinois River southwest of La Salle-Peru.
A century ago William Wirt Calkins wrote a report on the Lichen Flora of Chicago and Vicinity, which was published by the Chicago Academy of Sciences. Calkins described 125 species of lichens he had collected in Cook, Du Page, and Will counties in Illinois and in Lake County in Indiana. Current thought would lump some of these together, producing 109 total species.
Hyerczyk's fieldwork, combined with work done by Gerould Wilhelm of the Morton Arboretum, has discovered 111 species in Cook County. This total is very near Calkins's, but the numbers disguise a major shift in the lichen flora. Forty-nine species found by Calkins have not been found in recent years. The new species discovered recently are mainly organisms that grow on concrete. The species lost have almost certainly been done in by air pollution. Lichens, perhaps because they get their mineral nutrients from air and rainwater, are extremely vulnerable to pollution.
Wilhelm has been both a mentor in Hyerczyk's pursuit of lichens and a grateful beneficiary of his fieldwork for his own report, Lichens of the Chicago Region, which is currently in preparation. "A lot of young people think that everything is already known," Wilhelm told me, "because that's the way it is presented to them in school. But Rich found an area to work where very little is known. Everything he collected in Putnam County is a new record, because nobody ever looked for lichens there before."
You might ask why anybody would decide to devote so much attention to lichens. They are very obscure members of natural communities. Those 33 species at Harms Woods account for only a tiny fraction of 1 percent of the biomass of the preserve. Lichens are not major shapers of the community. They are not an essential food source for much of anything. Blue-gray gnatcatchers do build their nests with a gray lichen called Parmelia sulcata, and there is some reason to believe that parula warblers won't nest in places that don't have a lichen called Usnea sp., which the birds use for their nests. On the stony ground of the tundra the fruticose lichen called reindeer moss is a major food of reindeer and caribou.
And while lichens seem like small potatoes around here, when you get south of the regions that were once glaciated they get much more important. According to Wilhelm, on barren, rocky slopes in the Ozarks the ability of lichens to colonize bare rock makes them a major component of the ground cover. "You can't really understand what is going on in those communities without studying the lichens."
One of the things going on in those communities is a successional pattern. Lichens on bare rock collect dust. The dust combines with dead lichens to create a sort of soil that might support a flowering plant that could continue the soil-building process.
Of course the real reasons for studying lichens are first, that they are there, and second, because it's fun. And then there is that symbiosis. If you remember anything about lichens from biology class, you remember their unique hybrid nature. But is it unique? Wilhelm thinks it is more like a pattern that is repeated throughout nature. "Fungi typically have a relationship with another organism," he says. Fungi of decay have these relationships with dead organisms, but many fungi are symbiotes with living ones. Flowering plants have mycorrhizal fungi growing on their roots that play a major role in the absorption of minerals from the soil. The fungi can't live without the plant, and the plant can't live without the fungi. "Should we think of the white oak as a separate, independent organism?" Wilhelm asks. "Or should we think of it as part of a combination of fungi and green plant?" In other words, are oaks in their relationship to fungi just very large versions of the lichens that grow on their bark?
Meanwhile Hyerczyk continues to collect and continues to find intriguing things. Lichens are usually more common in open sunny areas and less common in shady woods. But when a large oak fell at Black Partridge Woods Forest Preserve Hyerczyk examined the crown of the tree and found 13 species of lichens growing in it. They had been up where the sunlight was. I suggested he needed the sort of rigs used to study the canopies of rain forests. He just smiled. I'm wondering if he might try it.
In keeping with the each-one-teach-one ethic of the people who work in ecological restoration, Hyerczyk offers lessons through the Volunteer Stewardship Network to anyone who wants to get into lichens. So far the crowds have not been beating down the door, but maybe people will wake up soon and start to take advantage of this opportunity to reduce the world's ignorance of these neat little organisms.