Bryophytes are important soil formers and soil protectors. They can settle where lichens have begun to convert bare rock surfaces to small patches of soil, and by their metabolism and decay contribute to a further transformation of rock to soil. Moreover, many bryophytes form dense, soil-covering carpets that minimize soil erosion and retain water between the closely spaced plants. Many bryophytes also absorb water directly through their leaves, which spares the water supply of the soil. In the course of time their bodies die and decay forming humus, increasing the soil fertility.
One kind of moss that is most important economically is the sphagnum or peat mosses. The species of peat moss grow in boggy places. Here they form dense and deep mosses that are often dried and used as fuel for domestic as well as industrial purposes. Dried up specimens of Sphagnum are used as an absorbent in surgical dressings, as packing material in upholstery for transshipment of living plants, and a material for increasing the water retaining property of certain poor types of soils. Flowers packed in moistened peat mosses keep fresh for a considerable period.
Classes of Bryophytes
Liverwort is so named as it resembles the liver in shape and was thus thought to be useful in treating liver ailments. In some liverworts, gametophytes grow flat along the ground and are relatively undifferentiated. In other liverworts the gametophytes have simple leaves, stems and rhizoids, resembling mosses in their complexity. The sporophytes of liverwort are often more or less spherical and usually are held within the gametophyte tissue until they shed their spores.
Hornwort gametophytes resemble Marchantia and similar genera among liverworts. The sporophytes of hornworts, however, differ remarkably from those of liverworts; they are elongated hornlike capsules arising from the surface of creeping gametophytes. Thus this name was given to this kind of plants.
Mosses can be found almost anywhere on earth. The gametophytes of mosses are almost always leafy, with small, simple leaves, that may be tufted or creeping. Sporophytes of mosses, are often yellowish or brownish at maturity, bear a sporangium or capsule near their tip and are borne individually on the gametophytes.
Many small-tufted plants are mistakenly called mosses. The "Spanish moss" for example is actually a flowering plant, a relative of the pineapple.