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Tetraphidaceae is a family of
moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...
es. It includes only the two
genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
'' Tetraphis'' and '' Tetrodontium'', each with two
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
. The defining feature of the family is the 4-toothed peristome.


Range

This family of mosses is most commonly found in northern latitudes.


''Tetraphis''

''
Tetraphis pellucida ''Tetraphis pellucida'', the pellucid four-tooth moss, is one of two species of moss in the acrocarpous genus ''Tetraphis''. Its name refers to its four large peristome teeth found on the sporophyte capsule. Range and morphology ''Tetraphis pel ...
'' is the most common species in the family and is usually found in deciduous forests. Its leaves become wider in colder climates, which often leads to a misclassification of the species. ''Tetraphis geniculata'' is less commonly found and also appears in northern latitudes. The species often grows alongside the only other species in the genus, ''T. pellucida''. Both ''Tetraphis'' species are found growing on moist sedimentary rocks and also on soil with high organic content, but the genus is mostly found growing on rotting logs.


''Tetrodontium''

'' Tetrodontium brownianum'' grows most frequently on wet and shady rocks, of either granite or sandstone. The species normally grows alone but has been found growing with other bryophytes. ''Tetrodontium repandum'' is extremely rare and has been found growing in parts of central Europe, western North America and southeast Asia.


Morphology

The most notable anatomical structure in the family Tetraphidaceae is the four teeth that make up the peristome. The teeth are whole, thick-walled cells which classifies the moss family as nematodontous. The teeth help the plant adapt as they can sense changes in the moisture in change length.


''Tetraphis''

The genus ''Tetraphis'' is made up of the species ''T. pellucida'' and ''T. geniculta''. The shoots on ''T. pellucida'' can be up to 1.5 cm tall and the lower leaves are often only 1 mm in length. The fertile shoot tips are longer with distinct leaves while the leaves on the sterile shoot tips are more clumped together. The crowded leaves of the non-fertile shoot tip may form a gemma cup. The capsule, which is only about 2–3 mm in length, contains the spores used in asexual reproduction and is made up of four peristome teeth. The capsule usually fruits around early summer and the green,
papillose This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...
spores are spread by wind. The main contrast between ''T. pellucida'' and ''T. geniculta'' is the characteristics of the
seta In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. Th ...
e. In ''T. pellucida'' the setae are smooth and straight while in ''T. geniculta'' they are bent and papillose. In their immature forms, it is often difficult to tell one species from another as the seta is not yet fully developed.


''Tetrodontium''

''Tetrodontium brownianum'' has short, bristle-like structures that grow out of the
protonema A protonema (plural: protonemata) is a thread-like chain of cells that forms the earliest stage of development of the gametophyte (the haploid phase) in the life cycle of mosses. When a moss first grows from a spore, it starts as a ''germ tube'', ...
l leaves. These structures can be up to 4 mm long and the protonemal leaves can be up to 2.5 mm long. Four triangular teeth make up the egg-shaped capsules which are normally only 1 mm long. The spores are smooth, in contrast to the papillose spores produced by species in the genus ''Tetraphis''. ''Tetrodontium repandum'' is very similar but has long, thin branches and the stem usually only grows to be about 2 mm in height. In some cases, a colony of ''Tetrodontium'' is made up only of the protonemal leaves. Additionally, ''Tetrodontium'' species do not have specialized asexual structures, in contrast to species in the genus ''Tetraphis''.


History of taxonomy

Johann Hedwig Johann Hedwig (8 December 1730 – 18 February 1799), also styled as Johannes Hedwig, was a German botanist notable for his studies of mosses. He is sometimes called the "father of bryology". He is known for his particular observations of sexual r ...
first described and named the genus ''Tetraphis'' and the species ''Tetraphis pellucida'' in his book ''Species Muscorum Frondosorum,'' published in 1801. In 1824
Christian Friedrich Schwägrichen Christian Friedrich Schwägrichen (16 September 1775, Leipzig – 2 May 1853, Leipzig) was a German botanist specializing in the field of bryology. In 1799 he obtained his medical doctorate from the University of Leipzig, where he was later an as ...
named the genus ''Tetrodontium''. The phylogeny and taxonomy of the family Tetraphidaceae, in relation to other bryophytes, have long been disputed among bryologists. Some believe that there are characteristics of the family, like the thalloid protonema or the development of the peristome, that indicate that the moss is primitive and may share a common ancestor with Sphagnopsida and Andreaeidae. The exact phylogeny of the family and its species continues to be discussed among bryologists.


References

{{Taxonbar, from=Q140306 Moss families Tetraphidopsida