sphagnum

sphagnum or peat moss, any species of the large and widely distributed genus Sphagnum, economically the most valuable moss . Sphagnums, the principal constituent of peat , typically grow as a floating mat on freshwater bogs . Their leaflike appendages have many large cells with circular openings that enable them to absorb liquids readily; hence they are commercially important as a soil structure enhancer (or component of potting soils), packing material, and absorbent dressings and for other uses. Sphagnum is classified in the division Bryophyta , class Bryopsida.

sphagnum (bot.) genus of mosses. XVIII. f. Gr. sphágnos
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Sphagnum (subclass Sphagnidae, class Musci) A genus of mosses which differ in several respects from other mosses; they are sometimes classified in a separate class (Sphagnopsida). The plants are characteristically branched with branches in fascicles of 2–8. The leaves are nerveless and are composed of 2 main types of cell: narrow, green, living cells and inflated, colourless, dead cells. The latter cells readily become filled with water, allowing the plant to hold many times its own weight of water. The capsules of Sphagnum are also unique; they are roughly spherical with no peristome. When the capsule is ripe, the wall shrinks on drying and the pressure inside builds up until the lid is blown off and the spores are ejected. There are many species, often difficult to distinguish, found, often abundantly, in various wet, acidic habitats: bogs, marshes, pools, moors, wet woodland, damp grassland, etc. The genus is distributed world-wide.