Mosses: Little-known pygmies of the plant world

StoryImage( ‘/Images/Story//Auto-img-112854156717033.jpg’, ”, ‘Moss covers a stone railing on a bridge in the Kishwaukee River Forest Preserve in Winnebago County.’);

For many years, botanists and evolutionary biologists believed the little-known group of small, primitive, multicellular plants known as the Bryophyta were the first plants to establish themselves on land. Bryophytes include the mosses and liverworts, and it was thought this group gave rise to the higher vascular and seed plants. Now it is believed colonial green algae were the first invaders of the land, and eventually evolved into the higher plants, with the mosses and liverworts constituting a side branch on the tree of evolution.

There are more than 1,500 different species of mosses to be found worldwide, and most of them seem to be drawn by nature to things old, barren, or unsightly. They cover the rocky mountainside, and soften the appearance of rock and dying trees. In many areas, they carpet the forest floor with a thick green covering. They provide nest-building material for birds, a mattress for the hibernating bear and, in pioneer days, were used as padding for the baby’s cradle.

If the student of nature closely studies a bed of moss with the naked eye or a hand lens, he will discover a strange and beautiful world in miniature. A myriad of bizarre shapes will be noted that may resemble evergreen trees, ferns, bird feathers, or a multitude of other shapes and forms.

The life cycle of a moss is rather complicated in that a sexual phase alternates with an asexual stage. In the sexual or gametophytic phase, the equivalent of sperm and eggs are produced and unite to form a zygote or fertilized egg, which grows into the asexual or spore (sporphytic)-producing stage.

The name moss is frequently incorrectly given to other plants, such as lichens, algae, and even some higher plants. For example, “Iceland Moss” is actually a lichen, and Spanish moss is a true flowering plant.

The names given to various true mosses by those who have studied them speak movingly of the charm these plants have exerted upon the naturalists. Wood revelers, little beard mosses, glittering feather moss, torn veil, golden cord, and fountain mosses are a few of the names that describe the beauty of these tiny plants. The Greek botanist Dioscoraides and the Roman naturalist Gaius Plinius gave many of the mosses names they still bear today.

Insignificant as the mosses may appear, they are essential to many higher plants and to the ecology of a region. They conserve moisture, prevent erosion, reclaim marshlands, and instigate the many streams that begin as rivulets seeping from a great bed of these plants.

Perhaps the most important Bryophyte is peat moss, or sphagnum moss. It is usually found in compact green and purple mats along the banks of streams and small lakes, and its sponge-like ability to absorb and retain water has made it valuable as mulch for other plants. Peat mosses have reclaimed vast areas of wasteland throughout the Northern Hemisphere, turning them into peat (a useful fuel), and some of the most fertile land to be found. The supply of peat in the United States is estimated to contain about 12,000,000 tons of fuel, and the ancient peat bogs of Ireland have yielded the primary fuel in parts of the Emerald Isle for centuries. These bogs are formed over many years by the compaction of the moss as it grows outward from the banks of a body of water, dies and sinks to the bottom. Eventually, the pond appears to be a lush meadow, but, beware: stepping into a peat meadow can cost an animal its life.

To anyone who enjoys the natural world, the study of mosses can be a fascinating hobby. A hand lens or a low-power microscope is the key that opens the door to this fascinating miniature world. A patch of moss can be no larger than the palm of your hand, and will often exhibit an overabundance of individual plants. On a field trip to study mosses, a multitude of specimens can be collected in a container no larger than a lunch box. Collections may be dried and stored in glassine envelopes, and kept almost indefinitely for future study. Specimens may be dried for storage by placing them between sheets of blotting paper and applying moderate pressure.

To anyone with a philosophical turn of mind (every true naturalist is something of a philosopher), the study of mosses offers an area of rich contemplation for some of nature’s most exquisite handiwork.

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

From the Oct. 5-11, 2005, issue

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