A genus of mosses, distributed worldwide, that are found, often abundantly, in wet, acidic habitats (bogs, marshes, pools, moors, wet woodland, damp grassland, etc.) There are many species, which are often difficult to distinguish. The plants are characteristically branched, with branches in fascicles of 2–8. The leaves are nerveless and composed of two main types of cell: narrow, green, living cells and inflated, colourless, dead cells. The dead cells readily fill with water, allowing the plant to hold many times its own weight of water. The capsules are roughly spherical; when ripe, the capsule wall shrinks when it dries, increasing the internal pressure until the lid is blown off, ejecting the spores. Sphagnum can absorb water up to at least 20 times its own dry weight. It is a bryophyte (moss) genus that covers more of the Earth's surface than any other plant, and probably accounts for more plant biomass than any other genus.
Subjects: Plant Sciences and Forestry — Ecology and Conservation.