I can imagine a landscape painter out in the woods in early April recording the first signs of spring. Almost all of the green brushstrokes, watercolor on paper, would represent the mosses. Walking along forested paths a few weeks ago, my son and I enjoyed stopping and petting pillow moss along the way. Everywhere, even along the roadsides, bright patches of moss on the trees deepened into emerald tones, a pleasant foreshadowing of long-awaited foliage. I was reminded of the many mosses I observed during the gray, misty winters I spent in the Pacific Northwest. Later I would learn that these ancient plants, besides possessing remarkable beauty, are ecological warriors.
There is something clean and fresh about moss that photos of carefully laid out moss gardens never seem to fully convey. After reading more about them, I realized this impression wasn’t far off the mark. Mosses typically have a one-cell-thick “leaf” through which they capture water, rather than through roots buried in the soil, so they are extremely susceptible to impurities in their environments. Unlike vascular plants, they cannot move water internally, which means they are vulnerable to dessication; however, they can revive after losing up to 98% of their water content and ceasing all metabolic activities, sometimes even reviving decades after drying out.
Professor of environmental and forest biology and acclaimed writer Robin Kimmerer began her scientific career researching moss. In her delightful book of essays on this topic, she explains that the presence or absence of moss on the trees in a locality closely aligns with air quality, especially a sensitivity to sulfur dioxide. In fact, U.S. Forest Service scientists study mosses as bioindicators of forest health, and the USDA had blogged about a promising 2013 study conducted in Portland, Oregon, in which moss was used to map air pollution in the city, even revealing previously unknown hot spots of cadmium.
During the school break, my son and I visited the fairy forest at Fruitlands. Alone beside the little moss-lined brook on a beautiful spring day, it was easy to picture young Louisa May Alcott and her sisters running in the woods and inventing stories about woodland creatures. Mosses often seem timeless, possibly because they evolved about 400 million years ago as life colonized the land. The development of the first land plants—mosses and liverworts—was revolutionary, as described by geobiology and biology professors Peter Ward and Joe Kirschvink. These plants, they contend, produced “radical changes” in the history of life—setting up the appropriate atmosphere, temperatures, and carbon cycling for the development of the complex land animals that followed: It’s possible we wouldn’t be here at all without moss.
It was a jarring experience, then, to go online recently to try to identify a moss growing in my lawn and find that almost all of the search results were about killing it. Kimmerer noted in her book that as a moss expert, she would receive inquiries from the public about how to get rid of it: She assures readers that even moss on roofs is not harmful from her observational experience because it does not have roots, but rather hair-like rhizoids to anchor to rocks and other surfaces.
Although underappreciated, moss provides many benefits to local and global environmental health. Peatlands formed by various sphagnum species hold about 25% of all the carbon stored in the world’s soil but cover only about 3% of total land surface according to a Nature magazine article from 2020. This means that peatlands store about twice as much carbon as forests globally. In general, moss species clean the air, regulate temperatures, and provide a key habitat for animals ranging from tardigrades to turtles. Owing to their absorptive and antiseptic qualities, they were used as bandages in World War I due to material shortages, according to a Smithsonian article from 2017, and as diapers and sanitary napkins among Indigenous communities, according to Kimmerer. In the forest, they cover dead logs and create mini-nurseries for new trees to grow. In your garden, they will slow runoff and capture chemicals from leaching into nearby bodies of water, prevent erosion, and provide a living mulch.
Still curious about the moss in my lawn, I turned to renowned horticulturist William Cullina’s book, “Native Ferns, Moss, and Grasses,” for a likely identification: big red stem moss Pleurozium schreberi, “a robust, mat-forming moss of cool forests.” Indeed, this moss forms an extensive mat beneath grass on my lawn (invisible to the casual observer) under some oak trees, in an area likely of very acidic soil and possibly low nitrogen. I discovered it when attempting to plant a Virginia rose on a small bank along my driveway. I had a very hard time getting my shovel into the soil, and I realized that the moss had formed a thick mat of dead stems upon which new growth continued to move upward, somewhat like the way sphagnum moss grows. (I may, of course, be incorrect about the moss ID, as microscopes are usually the recommended method for accuracy.)
Discovering this moss hiding under the grass, yet holding up the bank and preventing erosion probably far more robustly than any landscaper’s design, I remembered Kimmerer’s insights in her chapter in which she describes her quest to find out how Indigenous peoples used mosses: If you look carefully enough, she concludes, a plant will reveal its particular gifts; it goes where it is needed. I decided to find another patch, where the moss wasn’t already growing, to plant my wild rose. I wanted to leave the moss as I found it.
For more information
- For a wonderful introduction, see “Gathering Moss: A Natural and Cultural History of Mosses” by Robin Kimmerer, 2003.
- For information about common mosses of the Northeast and how to garden with them, see “Native Ferns, Moss & Grasses” by William Cullina, 2008.
Catherine Warner is an amateur gardener, freelance writer, and educational consultant who lives in Harvard with her family and their beloved dog Moe.
