Liking lichens
For those of us who enjoy the flowers of spring, it’s still a little early out there. One of the things I like about this time of year when the vegetation is down is it’s like the rocks come out.
Our beautiful ancient Ozarks landscape is peppered with rocks hidden behind a sea of leaves this time of year. But that doesn’t mean there’s no plant life to seen sand enjoy.
This winter a light bulb went off in my head when a new Facebook page appeared called ‘Arkansas Lichens, Mosses, and Ferns,” three plant groups that over a 45-year botanical career, frankly, I’ve paid little attention to. Here, though, using social media for its highest purpose—the opportunity to identify lower plants—I can post photos of micro scenes that have caught my attention. I have files of moss and lichen photos but have never done anything with them because I don’t have the tools and skills to identify the organisms.
Consider lichens. They are not plants! The more than 20,000 known species of lichens are composite organisms that cover 6–8 percent of the planet’s land surface from sea level to high alpine habitats and grown on about any surface from rubber boots abandoned in sticky mud to hot dry deserts. They come in all sorts of colors, sizes and structures.
Fruticose lichens have small leafless branches. Foliose lichens have leaf-like structures. Crustose lichens are flaky like peeling paint. Leprose lichens take on a powdery form. Some lichens a gelatinous or jelly-like. They are not “species” as the term is applied to plants and animals, because they are a combination of organisms from two or even three different kingdoms (queendoms?) of living entities.
If lichens are not plants, what are they? Lichens arise from symbiosis—a mutually beneficial relationship evolving from either algae or cynobacteria living among, and usually surrounded by filaments of fungi. The algae or cynobacteria use photosynthesis to produce carbohydrates that sustain the fungal filaments intertwined with them.
Lichens are slow growing, up to 1-2 mm per year, and are among the oldest living organisms, dated to 8,600 years of age, making them one of the oldest, if not the oldest living organisms on Earth.