Gathering Moss: A Natural and Cultural History of Mosses

Kimmerer recounts an odd experience she had one summer at her university’s Cranberry Lake Biological Station. She explains that she has been coming to the Bio Station for 20 years, and it is so familiar to her that she can walk its paths in darkness, without her flashlight. She knows where each rock and each tree root are located. She first came to the Bio Station for a class with Dr. Ketchledge, when she was an undergraduate. Dr. Ketchledge introduced her to mosses, and she was so excited by the class that she immediately bought herself a professional hand lens—it is the one she still wears around her neck to this day. Now, she brings her own students to the Bio Station. They are studying moss communities on the large, glacial boulders that dot this landscape. Kimmerer muses on the nicknames that humans have given to the various boulders and makes the point that most mosses only have Latin scientific names, because people do not pay much attention to mosses. She thinks that people are “outside the circle” of the moss community, and she wonders what mosses might call themselves, “within the circle” (3).

Because Kimmerer is so familiar with the Bio Station, she is shocked one day when she sees a formation of huge boulders she has never seen before. She discovers a cave and enters. Kimmerer’s family are members of the Potawatomi Bear Clan, and Kimmerer believes that in entering the cave, she is “following a Bear.” In a literal sense, there is no bear in the cave, but traditional stories about Bear link Bear with plant knowledge. Bear is the one who knows the names and stories of various plants (4). She climbs through the cave and emerges into a circular clearing surrounded by moss-covered rock. While she is in the clearing, she loses track of time and of herself, noticing nothing but the relationship of the stone to the moss. She explains that, as hard and durable as stone is, the delicate moss is actually slowly breaking the stone down into sand. While in the circle, she feels more certain that mosses have their own names apart from the ones humans have given them. When she leaves the clearing, finally, she feels that she has been given a gift: she is now both an outsider and an insider to the world of rocks and moss. In return for this gift, she is to spread the message that mosses have their own names.

While on a plane, Kimmerer muses about all of the life unfolding below her that she cannot see because of the plane’s height and speed. She notes that, without her reading glasses, she also cannot see what is happening right in front of her. She recalls having a similarly frustrating experience perceiving what her Indigenous guides in the Amazon could plainly see in the jungle around them. She thinks about technology aids to human vision—like microscopes and telescopes—and decides that often, the problem is not a lack of the physical ability to see but a failure of attention and imagination. She recalls her first trip to the North Pacific Ocean and how difficult it was for her to find her first starfish in a tidepool; finally, she spotted her first one, and after that she could see them everywhere. A Cheyenne elder once told Kimmerer that “the best way to find something is not to go looking for it” (9). Instead, he advocated staying generally attentive and simply open to the possibilities of what might be there. The sensation of suddenly being able to see something, as Kimmerer had with the starfish, depends on pattern recognition in the brain. Once the pattern is established in the mind, the brain can sort complex visual information more effectively and find what it is looking for.

Unless a person takes the time to really look carefully at mosses, looking at them can be like looking at the ground below from an airplane. Their complex features and diversity are lost. When closely observed, mosses reveal intricate patterns that mimic the larger world of the forest around them. Kimmerer thinks that “Learning to see mosses is more like listening than looking” (10). It requires deep attention and filtering of the surrounding visual “noise.” As a teacher of bryology (the study of mosses, liverworts, and hornworts), Kimmerer knows that acquiring precise descriptive language is also a part of learning to see. She takes pride in her students’ growing scientific vocabulary and in their growing understanding of what they are seeing as they learn the differences between things like “dentate” and “serrulate” leaf margins (12). She notes that this close observation and precise language helps her students develop intimacy with the mosses they are studying.

Kimmerer enjoys the Latinate names mosses are generally identified by, because she finds them pleasurable to say. Often, however, she comes up with informal nicknames for species until she learns their Latin names. She notes that the specific names are not the important thing: acknowledging the mosses’ individuality is. Indigenous peoples generally view all beings as “non-human persons,” and “It is a sign of respect to call a person by their name” (12). Kimmerer explains that even the word “moss” is often misapplied in casual speech, and she gives a scientific definition of what mosses actually are: the most primitive plants, lacking flowers, roots, seeds, fruits, and vascular systems. It is worthwhile to know these things, carefully observe mosses, and develop real intimacy with them, because this leads to greater understanding of and intimacy with the wider natural world.

Kimmerer recalls a time when her young niece threw a tantrum about being too small. She tried to reason with the child that there are advantages to being little. Mosses are small because they do not have structures that would hold them upright or allow them to stay hydrated if they grew larger. The advantage to their size is that they can inhabit a great diversity of tiny niches in the environment. Because they are generally shaded by larger plants, their chlorophyll differs from that of taller plants; it is optimized for filtered light. Where deciduous trees’ leaves carpet the forest floor, mosses can live on hard surfaces other plants cannot live on: rocks, stumps, and so on. Mosses thrive in the boundary layer—the place where air and land meet. The boundary layer experiences reduced wind speeds. Kimmerer uses the familiar example of flying kites to illustrate how wind speeds accelerate with distance from the earth’s surface. She describes running back and forth with a kite to generate enough speed to lift the kite into the air, because wind speeds are not sufficient at surface level. Once the kite is aloft, though, wind speeds are enough to keep it airborne.

The nearly still air of the boundary layer is warmer and moister than the surrounding air. This prolongs the growing season for moss and creates the moisture it requires for photosynthesis. Another advantage of life within the boundary layer is that it contains a higher concentration of carbon dioxide, which mosses also need for photosynthesis. Staying small allows mosses to exist entirely within this specialized microenvironment. They vary in size from about a millimeter in height to nearly ten centimeters in height, depending on the size of the boundary layer they typically inhabit. Mosses can influence the size of this boundary layer to an extent by the shape they assume as they grow, as their surface textures can further impede airflow and increase the height of the boundary layer. One disadvantage of life in the boundary layer is that it makes reproduction difficult. Mosses require wind to distribute their spores to new locations. In order to get these spores up into the moving air, mosses must grow long stalks to lift their spores above the boundary layer.

One spring night, Kimmerer goes to stand by the pond, drawn by the calling of the frogs known as peepers. She thinks about the frogs gathering to mate in this watery landscape. She notes that “Mosses are the amphibians of the plant world,” because they are the first plants to colonize land, “a halfway point between algae and higher land plants” (21). Their aquatic ancestry shows in the way they have to recreate a very wet environment in order to breed. She shares a Zuni traditional story about all life beginning with algae and notes that this aligns with Western science’s understanding that life originated in the water. Because the earth originally had no ozone layer, life could only exist where the sun’s UV radiation was filtered by water. Over time, the oxygen released as a byproduct of photosynthesis by water plants built up in the planet’s atmosphere and was converted into ozone. This filtered UV radiation enough for life forms to leave the water and live on land.

Life in the water is easy for algae. Their lack of roots, leaves, flowers, and other structures does not matter, as the water itself provides support, nutrients, and a mechanism for circulating egg and sperm to create future generations of algae. 350 million years ago, however, some algae did leave the water and adapt to life on land. These adapted plants were the first mosses. Mosses’ main challenge in life outside of the water is breeding. Just as the peepers’ eggs and sperm cannot survive outside of water, the eggs and sperm of mosses require water to survive and to act as the mechanism of circulation. The leaves of mosses channel environmental water—rain, condensation, and so on—into miniature rivers flowing between individual moss plants, carrying sperm from one plant to another. If the flow of water is broken, reproduction cannot occur. In dry years and in dry climates, mosses struggle to reproduce.

Because moss sperm are so tiny and such weak swimmers, mosses have adapted to give them some help in their aquatic journey. Just before the sperm are to be released from the antheridium (the male reproductive part of a moss), the antheridium soaks up extra water so that it can eject the sperm in a gush of water, giving the sperm a head start. The sperm are also surrounded with a surfactant that reduces the viscosity of the water the sperm have to swim through. If their journey results in the fertilization of an egg, a sporophyte forms and grows inside the archegonium (the female reproductive part of a moss). Once the sporophyte is mature, it releases powdery spores that will ride the wind to new locations. The spores that land where there is sufficient moisture send out branching tendrils, gradually creating a green web. Eventually, this primitive structure sends up stems and leaves, and at this point it finally resembles other mosses. This reproductive process is so precarious that many mosses have evolved to propagate through nonsexual means. A single leaf, broken from its original plant, can create a clone of the original moss. Mosses have evolved a variety of other asexual mechanisms for reproduction as well.