Sphagnum is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, also bog moss and quacker moss. Accumulations of Sphagnum can store water, since both living and dead plants can hold large quantities of water inside their cells; plants may hold 16 to 26 times as much water as their dry weight, depending on the species. The empty cells help retain water in drier conditions.
Sphagnum
Sphagnum cells
Red sphagnum closeup
Sphagnum with northern pitcher plants (Sarracenia purpurea) at Brown's Lake Bog, Ohio
Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta sensu stricto. Bryophyta may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hornworts. Mosses typically form dense green clumps or mats, often in damp or shady locations. The individual plants are usually composed of simple leaves that are generally only one cell thick, attached to a stem that may be branched or unbranched and has only a limited role in conducting water and nutrients. Although some species have conducting tissues, these are generally poorly developed and structurally different from similar tissue found in vascular plants. Mosses do not have seeds and after fertilisation develop sporophytes with unbranched stalks topped with single capsules containing spores. They are typically 0.2–10 cm (0.1–3.9 in) tall, though some species are much larger. Dawsonia, the tallest moss in the world, can grow to 50 cm (20 in) in height. There are approximately 12,000 species.
Moss
Chloroplasts (green discs) and accumulated starch granules in cells of Bryum capillare
Moss leaf under microscope, showing gemmae and a hair point (40x)
A patch of moss showing both gametophytes (the low, leaf-like forms) and sporophytes (the tall, stalk-like forms)