One of the questions that I hear from callers and clients goes something like this: “The branches are covered with moss and I think it’s killing my trees.” Or shrubs. They have noticed that some of their plants are looking thinner, or bare, and that the stems are also covered with fuzzy green stuff. Is this moss like coating causing the decline of the shrubs or trees?
What these people are noticing is not moss, but lichen. There are many colors, types and sizes of lichen and although they are plant-like (they photosynthesize) they are not actually plants. Simply put, when algae or cyanobacteria, or the two together, get together with a fungus, these new BFF’s form a lichen and live happily ever after, creating their nourishment from sunlight, water, air and surrounding minerals. They are epiphytes, not parasites, meaning that they live on plants or other surfaces but don’t take any nourishment from those support structures.
At this time of year we notice lichen because other foliage is dying away and since there is often more frequent rainfall, the lichen swell and are more showy. The trees and shrubs that are thinner have more lichen because their reduced foliage allows more sunlight in and the lichens are better able to grow. Those plants that are under stress from drought, storms, insect pests or diseases are more likely to be a host to lichen just because they have fewer leaves so the lichen takes advantage of the increased sunlight.
Throughout history lichen has been used to dye yarn and cloth, but it has also been used medicinally in many countries and cultures. Gardeners appreciate them for their appearance. Lichens are quite beautiful, and noticing that beauty requires us to slow down, look closely, and pay attention.