Knee Deep in Moss

"One touch of nature makes the whole world kin." --William Shakespeare

I have always loved to see moss cozying up to the feet of trees, draping over decomposing logs, and cushioning rock surfaces with luxuriant velvet.

A neat thing about mosses is that to get to know them in their natural habitat you must usually get down on your knees. Doing so immediately takes you out of your usual way of looking and perceiving and engages you physically.

Your hands and knees ground you at four points. Perhaps your trousers get damp and a little dirty. You feel the different textures of the leaf litter and inhale the perfume of the humus. You stroke the furry surface of the moss and it tickles your hands.

You marvel at the vibrant shades of green that seem to glow amidst the surrounding shades of brown and grey. Or perhaps the moss serves as an emerald background for jewel toned fall leaves.

The undulating surface when seen from your full height now becomes a miniature jungle of lush intricate plants. Moving your face ever closer, tensing the muscles around your eyes to sharpen your powers of sight, you attempt, but just fail, to focus clearly on the details you know are there. You bump up against the limits of the human eye.

You are literally brought down and humbled by this so-called 'primitive' plant. But you are also lifted up in awe. I find that nature frequently brings me to a kneeling posture, physically or otherwise.

Mosses have been much on my mind lately as our nature writing group has been reading Robin Wall Kimmerer's Gathering Moss: A Natural and Cultural History of Mosses. Kimmerer is a bryologist, a botanist specializing in mosses and liverworts--or bryophytes. She is also a descendant of North America's indigenous people. Her writing is scientific but also rich with mood, metaphor, myth and sensuality. She is the type of nature writer with whom I feel a kindred spirit.
Mosses will divulge many of their secrets, through the use of tools like hand lens, microscope, and field guide. Different families among the bryophytes are easily distinguished but species identification can be very challenging. I like to think of bryophtyes as a phenomenon, a clan of diverse members, sharing kinship not only among themselves, but as ancestors of other land plants. In some ways they are strikingly similar even to us mammals.

From Kimmerer's book, I learned that mosses are the 'amphibians' of plants. They are the ancient form of plant life that first transitioned from the water to land. Mosses live in communities or colonies with individual plants huddled together shoulder to shoulder. Their life style and reproductive cycle is dependent on this close proximity.

Moss have no roots to take up water from from where they are anchored--their substrate. They dry up, fade and shrink or plump up and green out depending on environmental conditions. The plant takes in CO2, water and minerals through its entire surface. Living close together helps them retain moisture not only for themselves but as participants in an ecosystem. Other organisms benefit. For example, many insects utilize the moist protection of mosses for their own reproductive cycle.

Moss plants occur in two life stages. In the gametophyte stage the plants are green and grow without sexual reproduction. When conditions are right, the gametophytes form microscopic male or female organs. The male structure containing sperm is called the antheridium. The female structure containing the egg is called the archegonium. This a reproductive innovation which mosses first developed. All land plants living today use this strategy of enclosing the egg within a protective womb.

Mosses produce no flowers so they ask for no help by animal pollinators. (Insects inadvertently do help the process along sometimes.) For the male sperm to reach and fertilize the female egg there must be a fluid vehicle. Rain, dew, mist or splashes are required. With sufficient moisture, the antheridum swells until it bursts. It also releases a soaplike substance that helps the miniscule sperm penetrate the surface tension of water droplets to better hitch a ride.

With luck the sperm is able to reach and travel down the neck of an archegonium to an egg.

Once fertilized, the egg is nurtured within the archegonium and grows into the second life stage--the sporophyte. Kimmerer explains science has discovered special cells in the female moss organ that work to transfer nutrients from the parent plant to the developing egg. She compares this function to human placental cells.

Mature sporophytes are usually brown or colorless with a capsule full of powdery spores elevated on a stalk above the green gametophytes. Special teethlike structures on the capsules are responsive to the level of humidity. They open to release the spores when the air is dry (and thus better for dissemination).

Those spores that find a hospitable home will form a new colony of moss, carrying the genetic material of the parent colony forward. The scattered colonies of particular moss species in a patch of woods are all close kin to one another.

Mosses are extremely adaptable--they are found in every ecosystem on earth. Species number over 22,000. Their variety is seemingly endless. Next time you go walking in the woods spend some time on your knees.

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