by Don Culwell, SFNC docent
Most all of fall’s color has faded, many leaves have fallen or have been driven downward by the wind, and few living blades seem to be around anywhere…it is what some may call the “dead of winter.” These days are the times when it is exciting to be outside on a pleasant, sunny day looking at the mosses and lichens that are all alive and well.
Without the major green leaves of the forest and the grasses and forbs along the path or in the glade, one can more easily find the little hummocks of green that are mosses or the colorful lichens on bare soil or rock surfaces…they show up now. Bark surfaces of trees provide a place for the microscopic moss spores, blown there by the wind, to germinate and grow into long, branching threads we call protonema. And they cover the bark on trees everywhere, and even can be seen on the surface of the bare ground and rock producing a greenish cast (almost like that of a coating of green algae) for the critically observant eye. It is from this minute matt of moss protonema that small leaves, just several cells thick, grow on tiny stalks as they make a soft, velvety covering of moss plants, the small stalks bearing clusters or stacks of leaves more obvious to the human eye (or, I suppose, that of the observant skink or turtle, as well)…these green mosses are more obvious than the protonema were. Green moss leaves, tiny and thin as they are, photosynthesize just as any other plant structure with chloroplasts…they are “producers” in the ecosystem, producers that are just “going to town” now in the light of the winter landscape…these leaves are more readily seen in winter, and are of such delicate beauty, especially when seen through a hand lens. Can you spot the tiny teeth along the margins of a moss leaf…and the midrib stands out, too!
So many of these tiny leaves all arranged on each moss stalk gather moisture from the dew-fall, from a mist of the wet air, or from a more drenching rain. (You see, mosses have no vascular system with which to transport water from their “roots” up to these “leaves.”) Water soaked in through the leaf surfaces and the carbon dioxide absorbed from the air provide the raw materials from which the photosynthetic machinery of each cell (powered by light) is enabled to assemble molecules of sugar. And it is this sugar that provides the nutrients for life needed by the moss plant itself. The moss hummock or moss covering of the tree bark grows into the soft, velvety surface that always beckons a gentle touch of the hand…just gently feel it…go ahead!
Do go out and enjoy the bryophyte flora we call mosses…do it today!