A vertical rock face at 12,000 feet above sea level . . . the furrowed bark of a three-hundred-year old Engelmann spruce . . . a concrete bridge abutment on the Snake River . . . these are not places one thinks of as habitat for plant life, yet, in all of these, and many other seemingly unlikely locations, mosses and liverworts thrive.
Mosses and liverworts belong to a group of plants known as bryophytes. Bryophytes are believed to be the first green plants to establish themselves on land. Fossil records date bryophytes to at least the Carboniferous Period, 350 million years ago.
Although mosses and liverworts bear some resemblance to vascular plants (plants with nutrient transporting tissues such as roots, stems, and veined leaves) they are actually quite different. Bryophytes have no transporting stems or roots. Instead, they absorb needed nutrients directly through surface tissues. This allows bryophytes to exist without soil. Bryophytes use tissues called rhizoids to attach themselves to surfaces on which to grow. Their chief method of reproduction is quite unlike vascular plants. Rather than being transported by wind or animals, the sperm of bryophytes must swim to the ovaries for fertilization to take place. These plants must have exposure to rainfall or live in a moist environment. This process may be a remnant of their aquatic ancestry. The result of fertilization is the production of spores, which are then dispersed via wind to form new colonies.
Bryophytes serve the ecological community of Grand Teton National Park in a number of ways. They are excellent soil stabilizers. They provide food, moisture, and habitat to many animal species. They also provide the organic material needed for other plant types to colonize previously barren areas. Like lichens, bryophytes are valuable indicators of air and water quality.
