By Bill Lawyer
My neighborhood, which I call “Halsted Hill,” has a large number of properties that include rock retaining walls and natural outcroppings. They provide delineation of different parts of the yard, as well as texture in their own right.
For those of us whose properties are along the slope of Halsted Hill, we have little choice but to divide it into terraces to provide level areas in back and front yards.
While the rocky terraces provide texture, the rocks themselves are the bare canvasses on which nature can create colorful, albeit somewhat abstract expressionistic, works of art.
We’re not talking about those chalk drawings your kids like to create in your driveway. We’re talking about the twin natural mixed media known as lichen and moss. One gardener refers to them as enhancing the walls with a “weathered, rustic appearance.”
While you have likely these two are, or how they got to where they are. Moss is a plant that does not produce flowers. Lichen, on the other hand, is not even a plant!
Lichens may superficially look like mosses, and have common names that include the word moss (e.g., “reindeer moss” or “iceland moss”), but they are not related to mosses, according to Irwin Brodo and Sylvia Sharnoff, co-authors of “Lichens of North America.”
Lichens are actually two or more organisms living together in what ecologists call a mutualistic relationship. They consist of an algae and a fungus, and in some cases even types of bacteria.
Most of the lichens that can be found in the rocks in Rye get their gray or green (or verdigris) from the color of the rocks themselves. Verdigris is the common name for the natural patina formed when copper, brass, or bronze in the rock is weathered and exposed to salt air or seawater over a period of time.
In fact, while the saltiness of seawater in Rye can cause serious damage to trees, it helps with nature’s artistic endeavor in coloring the rocks. A man-made version of this can be seen in the Statue of Liberty.
But along with verdigris around Rye, two other colors are commonly being produced in our rocky walls and outcropping — yellow and orange. Perhaps we don’t always notice these, as the brightness of the colors vary, depending on climate conditions and character of the rocks.
Wet weather enhances the brightness of the colors. According to research done at Michigan State University, photosynthetic chemicals — such as usnic acid — are responsible for red, orange, yellow, and brown.
Turning now to how mosses can provide color and texture to the landscape, we are immediately confronted by the fact that they are not plants, and they don’t use a vascular system to transport moisture and nutrients. So they don’t grow the same way as grasses, flowers, shrubs, and trees.
Perhaps the most commonly known moss in use is sphagnum moss — peat. Like most mosses, peat can absorb up to 20 times its own weight in water. This provides a great medium for keeping new plants moist.
To get ideas of how to use moss artistically in a garden, visit one of the region’s famed botanical gardens, New York and Brooklyn. A little further afield, in Raleigh, North Carolina, is the Moss and Stone Garden, which is dedicated to the promotion and cultivation of moss as a beneficial and appreciated component in the landscape. In their unique gardens and containers, moss rules supreme.
As plants that like shade, mosses can bring a softness and tranquility to public and private landscapes.
A few years back, The New York Times published an article about a Bucks County man who changed his entire lawn into a moss garden. And since then, he no longer has had to water, fertilize, or mow his yard.
As you start thinking about what to plant in the months ahead, why not give the dynamic duo of moss and algae a try, right in your own backyard.
Stonewall along Rye Beach Avenue
A moss garden created by the Moss and Stone garden company