page_title: Moss
section_title: Classification
hierarchical_section_title: Moss / Classification
caption_attribution_description: For index to numbers, see here. Thamnium alopecurum (Linné) = Thamnobryum alopecurum (Hedw.) Nieuwl. ex Gangulee Eurhynchium praelongum (Linné) = Eurhynchium pumilum (Wilson) Schimp. Polytrichum commune (Linné) = Polytrichum commune Hedw. Sphagnum cymbifolium (Ehrhard) = Sphagnum palustre L. Splachnum luteum (Linné) = Splachnum luteum Hedw. Mnium undulatum (Hedwig) = Hypnum ligulatum F.Weber &amp; D.Mohr Rhodobryum roseum (Schreber) = Rhodobryum roseum (Hedw.) Limpr. Physcomitrium acuminatum (Schleich.) = Physcomitrium eurystomum Sendtn. Physcomitrium ericetorum (Notaris) = Physcomitrium ericetorum (De Not.) Bruch &amp; Schimp. Physcomitrium sphaericum (Schwaeg.) = Physcomitrium sphaericum (C.F. Ludw.) Fürnr. Sphagnum medium (Limpricht) = Sphagnum magellanicum Brid. Andreaea Thedenii (Schimper) = Andreaea obovata Thed. Hypnum castrense (Linné) = Hypnum crista-castrensis Hedw. Tetraplodon urceolatus (Schimper) = Tetraplodon urceolatus (Hedw.) Bruch &amp; Schimp. Dissodon Hornschuchii (Greville) = Tayloria hornschuchii (Grev. &amp; Arn.) Broth. Dissodon Froelichii (Hedwig) = Tayloria froelichiana (Hedw.) Mitt. ex Broth.
context_page_description: Mosses, or the taxonomic division Bryophyta, are small, non-vascular flowerless plants that 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 tall, though some species are much larger. Dawsonia, the tallest moss in the world, can grow to 50 cm in height.
  Mosses are commonly confused with hornworts, liverworts and lichens. Mosses were formerly grouped with the hornworts and liverworts as "non-vascular" plants in the division "bryophytes", all of them having the haploid gametophyte generation as the dominant phase of the life cycle.
context_section_description: Traditionally, mosses were grouped with the liverworts and hornworts in the division Bryophyta (bryophytes, or Bryophyta sensu lato), within which the mosses made up the class Musci. However, this definition of Bryophyta was paraphyletic, as the mosses appear to be more closely related to vascular plants than to liverworts. Bryophytes are now split into three divisions: Bryophyta, Marchantiophyta and Anthocerotophyta. The current circumscription of Bryophyta includes only the mosses.
  The mosses, now division Bryophyta (Bryophyta sensu stricto), are divided into eight classes:
  Six of the eight classes contain only one or two genera each. Polytrichopsida includes 23 genera, and Bryopsida includes the majority of moss diversity with over 95% of moss species belonging to this class.
  The Sphagnopsida, the peat-mosses, comprise the two living genera Ambuchanania and Sphagnum, as well as fossil taxa. However, the genus Sphagnum is a diverse, widespread, and economically important one. These large mosses form extensive acidic bogs in peat swamps. The leaves of Sphagnum have large dead cells alternating with living photosynthetic cells. The dead cells help to store water. Aside from this character, the unique branching, thallose (flat and expanded) protonema, and explosively rupturing sporangium place it apart from other mosses.
  Andreaeopsida and Andreaeobryopsida are distinguished by the biseriate (two rows of cells) rhizoids, multiseriate (many rows of cells) protonema, and sporangium that splits along longitudinal lines. Most mosses have capsules that open at the top.
  Polytrichopsida have leaves with sets of parallel lamellae, flaps of chloroplast-containing cells that look like the fins on a heat sink. These carry out photosynthesis and may help to conserve moisture by partially enclosing the gas exchange surfaces. The Polytrichopsida differ from other mosses in other details of their development and anatomy too, and can also become larger than most other mosses, with e.g., Polytrichum commune forming cushions up to 40 cm (16 in) high. The tallest land moss, a member of the Polytrichidae is probably Dawsonia superba, a native to New Zealand and other parts of Australasia.
caption: "Muscinae" from Ernst Haeckel's Kunstformen der Natur, 1904
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