There are over 12,000 species of moss and it grows on all seven continents. It is a plant, not a fungus as some people believe, however, there are some interesting differences that separate mosses from other plants. Unlike vascular plants, the root system of moss is not responsible for the absorption of water and nutrients. Moss is non-vascular, so the roots only serve as anchors to hold it in place. Moisture and nutrients are absorbed through the leaves. Mosses appeared during the Permian Period, about 300 million years ago and at this point, it seems that these living fossils are our oldest plants.
Mosses are both dioecious and monoicous, meaning that some species produce distinct male and female plants, (like hollies) while others have both male and female parts on the same plant. (squash) Unlike the majority of the plant world, mosses produce spores, much like their equally ancient neighbors, the ferns. Water is needed for moss to bloom and produce spores, that's why you often see the little threads of blooms right after a rain.
Humans have used mosses for a number of purposes for thousands of years. It makes an excellent insulator and early dwellings often had cracks and holes packed with moss. They also discovered that dry moss was quite absorbent and was handy for packing wounds. It even has some antiseptic properties, so infections were less likely when a moss bandage was applied.
Generally, mosses prefer shade or filtered light, but do need enough sunlight to photosynthesize. They require constant moisture to be healthy and happy, however, they are quite tough and can go into a dormant stage where they appear dead, only to revive when conditions are right. Many gardeners with shady, woodland gardens try to encourage mosses because they offer a texture and appearance that traditional plants can't mimic. They thrive best in acid conditions, that's why some moss 'recipes' call for mixing it with buttermilk. Just whirl a few chunks of moss in a blender with a cup of buttermilk and paint the resulting liquid on rocks, walls or fallen logs to encourage new growth. My advice is to purchase a blender at a second-hand shop for this purpose though. Your family may take a dim view of using your good kitchen appliances for this task! If you actually want to prevent moss, raise the pH of the area with some lime and provide good drainage so the ground doesn't stay damp, but I like it and encourage it wherever I can. A healthy stand of moss prevents grass from growing and cuts down on mowing chores!
If you want to start your own moss garden, gently lift chunks and sheets from a moss-covered area and place it on ground that you have cleared and dampened. Press it firmly to make contact with the soil and water daily until the support system attaches. Mosses even make excellent container plants, just remember to be diligent in keeping your shallow container hydrated adequately. Also make sure that you have permission from the land owner to harvest a bit of moss and remember that it is illegal to take plants and items from federal lands.
Mosses provide an interesting texture to the garden and a living mulch. If the conditions are right, try some in your garden this season!
(Thanks to photographer Lisa Neal for the image of the moss in bloom)