A moss plant has a stem and leaves and no roots. The thin stalk on top (the seta) supports a capsule full of spores. Photos by Sarah Walker.

by Sarah Walker, from the October 2006 Newsletter

Mosses grow all over Moscow, on rocks, sidewalks, walls, tree trunks and roofs. Most any undisturbed surface can become mossy . . . like the old leather boots I left outside for a couple of years…

I asked my friend Karen, who is a bryologist (one who studies mosses), about the mosses that grow on the shady sides of roofs.

We took a walk on a hot summer evening through the alleys where there are old sheds with roof gardens, and plucked off a clump of Twisted, or Star, moss (Tortula ruralis). It was dark reddish-brown, dried up and brittle. Tortula is a common moss that grows in towns, tundra, forest, grassland or desert, on rock or soil (many moss species are specific to just one surface or substrate).

A clump of moss is actually a mass of separate moss plants. Under Karen’s microscope they looked shriveled and drawn apart from each other with dark leaves twisted upward around the stem. Then we sprinkled a little water.

The transformation from dry to wet is startling and beautiful to observe. In seconds the upper leaves turned bright yellowish green, untwisted and arched out. The plumped-up plants felt moist and soft and pushed against each other. The wiry stems holding the capsules shifted and tipped and the whole clump actually moved slightly.

How does moss “come alive” like this?

Moss plants absorb water through their whole surface. They don’t have an internal pumping system like flowers and trees for sucking water up from the soil through their roots. Instead they have delicate leaves, as thin as just one layer of cells that are always ready for any moisture from a light dew to a steady rain. It only took a few seconds for our dried up Tortula to transform into a fresh green plant ready to grow. (They lose water just as quickly).

Mosses survive by giving in to what’s around them. They can remain alive whether wet or dry. Flowers and trees die if they dry out.

Mosses grow all over the world in habitats from arctic to desert. They drape over trees, cover rocks, or form cushions on soil. Many plants called “moss” are something else: Spanish moss is a flowering plant that drapes over Live Oak branches. Reindeer moss is a gray-green lichen on rock ledges. Irish moss is an algae. Old Man’s Beard is a black lichen hanging from conifer branches in our forests.

There are over 20,000 species of moss worldwide. They can look like miniature feathers, ferns, palm trees, or green flowers. Mats of moss on the ground keep soil from drying out, to the benefit of the moss’s taller neighbors. A thick bed of moss is habitat for small insects.

Mosses glue soil in place, but must be left alone to do their job. A plowed field loses topsoil in the wind. A trampled campsite can become a dust bowl.

Mosses can be treated poorly, doused in harsh solutions to eliminate them from lawns and roofs (a stiff broom works fine on a roof), or harvested, baled and sold as peat (sphagnum).

But they are appreciated for their beauty—moss gardening is becoming popular. Children know that mosses are perfect for a secret fairyland in a terrarium. Moscow author Sarah Swett includes a section on setting up a little moss garden and weaving a tiny fence for it, in her book, Kids Weaving.

I’ve been noticing that some branches of natural history are gender specific. Most bird guides are written by men. Mosses attract women. Not all bryologists are women, but it was Fay MacFadden whose collecting work provided the data for the first list of mosses in Idaho, Elva Lawton who produced the first comprehensive moss flora for the Pacific Northwest, and Alma Hanson who researched bryophyte communities of central Idaho forests.

Mosses dry out (left) but within seconds of getting wet they turn green, ready to grow and photosynthesize (right).

Copyright: Copyright on articles, recipes and images are jointly held by the Moscow Food Co-op and the respective contributors, except were otherwise noted.

Return to Resource Archive

For additions or corrections to this page, please contact the Webmaster.