Plagiobryum

Plagiobryum
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Embryophytes
Division: Bryophyta
Class: Bryopsida
Subclass: Bryidae
Order: Bryales
Family: Bryaceae
Genus: Plagiobryum
Lindb.

Plagiobryum is a genus of mosses belonging to the family Bryaceae. It has a cosmopolitan distribution.[1]

The genus is part of the bryaceous mosses traditionally grouped within the subfamily Bryoideae. Plagiobryum was established by Swedish botanist Sextus Otto Lindberg in the 19th century, and the genus has subsequently been treated in a number of taxonomic studies of the family Bryaceae.[2]

Taxonomy

Plagiobryum is currently recognised as a genus within Bryaceae and is included in the order Bryales. The genus has a long history of taxonomic treatment within the Bryaceae, a family whose generic boundaries have been reassessed using both morphological and molecular evidence.[3]

Phylogenetic studies of Bryaceae have shown that relationships among several traditional genera cannot always be inferred reliably from morphology alone. Molecular and morphological analyses have therefore contributed to changes in the circumscription of genera within the family, including the treatment of taxa historically associated with Bryum and related genera.[4][5]

Some names historically associated with Plagiobryum have subsequently been transferred to other genera in particular taxonomic treatments. For example, databases currently list some former combinations of Plagiobryum under Ptychostomum, illustrating the continuing revision of species boundaries and generic concepts within Bryaceae.[6]

Morphology

Species of Plagiobryum are small mosses that commonly form dense tufts. Published descriptions of the genus indicate that plants may be approximately 20–40 mm tall and can have a silvery green, green, brownish or reddish appearance, depending on the species and condition of the plants.[7]

The leaves are generally closely arranged along the stem and are described as ovate- or oblong-lanceolate, concave and usually with entire margins. The costa may reach the apex or end below it, while the laminal cells are relatively lax and thin-walled.[8]

The sporophytes are characterised by solitary setae and relatively large, inclined to almost horizontal capsules. The capsules are often pyriform and somewhat asymmetric, with a distinctly developed neck. The peristome is double, with 16 exostome teeth and an endostome that may be reduced in some species.[9]

A characteristic used in distinguishing the genus in morphological classifications is its relatively large, gibbous or somewhat asymmetric capsules with an oblique mouth. These features have been used in comparisons with other bryaceous genera.[10]

Distribution and habitat

Plagiobryum has been reported from widely separated parts of the world. Species assigned to the genus occur in temperate, montane and other suitable habitats, and individual species may have relatively restricted geographic ranges.[1]

The genus includes species occurring in North America, Europe, Asia, Australasia and other regions. For example, Plagiobryum novaeeseelandiae is documented from New Zealand, where it is associated with higher-elevation habitats.[11]

In the continental United States and Canada, Plagiobryum is represented by species including P. demissum, P. hultenii and P. zieri according to a current North American moss checklist.[12]

The habitats occupied by species of the genus vary geographically. Depending on the species, plants may occur on soil, rock or other exposed substrates, particularly in cool, moist or montane environments.[13]

Reproduction

As with other mosses, species of Plagiobryum have an alternation of generations in which the dominant life stage is the haploid gametophyte. The sporophyte develops from the fertilised egg and produces spores that allow the plant to disperse to new sites.

The structure of the sporophyte, including the seta, capsule and peristome, is particularly important in species identification and has historically been used in the taxonomy of the genus.[14]

Species

The following species are recognised in the genus Plagiobryum:[1]

  • Plagiobryum demissum (Hook.) Lindb.
  • Plagiobryum duthiei Hedderson & Harold, 1990
  • Plagiobryum giraldii Paris, 1897
  • Plagiobryum hultenii Hedderson, 1990
  • Plagiobryum japonicum Noguchi, 1952
  • Plagiobryum laxum Demaret & Potier de la Varde, 1944
  • Plagiobryum novaeseelandiae Brotherus, 1916
  • Plagiobryum piliferum Potier de la Varde, 1955
  • Plagiobryum zierii (Dicks. ex Hedw.) Lindb.

Taxonomic databases and regional floras may differ in the number of species assigned to Plagiobryum because some species have been transferred between genera or treated under alternative combinations.[15][16]

Etymology

The name Plagiobryum was formed from the Greek words plagios, meaning "oblique" or "slanting", and bryon, meaning "moss". The name refers to the characteristic oblique or curved capsules found in the genus.[17]

Taxonomic research

Plagiobryum has been included in molecular and morphological studies examining relationships within Bryaceae. Research combining chloroplast DNA evidence and morphology has contributed to a better understanding of relationships among bryaceous genera and has also demonstrated that some traditional morphological groupings require reassessment.[18]

Later analyses combining molecular and morphological characters have continued to examine the evolutionary relationships of Plagiobryum and other members of Bryaceae.[19]

See also

References

  1. 1 2 3 "Plagiobryum Lindb". GBIF. Retrieved 3 March 2021.
  2. ↑ "Plagiobryum Lindb". Integrated Taxonomic Information System. Retrieved 22 August 2026.
  3. ↑ "Plagiobryum Lindb". Integrated Taxonomic Information System. Retrieved 22 August 2026.
  4. ↑ Spence, John R.; Ramsay, H. Peter (2002). "Phylogenetic relationships within the moss family Bryaceae based on chloroplast DNA evidence". Bryologist. Retrieved 22 August 2026.
  5. ↑ "Systematics and morphological evolution within the moss family Bryaceae: A comparison between parsimony and Bayesian methods for reconstruction of ancestral character states". Molecular Phylogenetics and Evolution. 2007. Retrieved 22 August 2026.
  6. ↑ "Plagiobryum demissum (Hook.) Lindb". GBIF. Retrieved 22 August 2026.
  7. ↑ Flora of Australia, Volume 51: Mosses 1 (PDF) (Report). Australian Biological Resources Study. Retrieved 22 August 2026.
  8. ↑ Flora of Australia, Volume 51: Mosses 1 (PDF) (Report). Australian Biological Resources Study. Retrieved 22 August 2026.
  9. ↑ Flora of Australia, Volume 51: Mosses 1 (PDF) (Report). Australian Biological Resources Study. Retrieved 22 August 2026.
  10. ↑ "Systematics and morphological evolution within the moss family Bryaceae: A comparison between parsimony and Bayesian methods for reconstruction of ancestral character states". Molecular Phylogenetics and Evolution. 2007. Retrieved 22 August 2026.
  11. ↑ "Plagiobryum novae-seelandiae Broth". Flora of New Zealand. Retrieved 22 August 2026.
  12. ↑ "Checklist of Mosses of the Continental United States and Canada". University of Connecticut. Retrieved 22 August 2026.
  13. ↑ Flora of Australia, Volume 51: Mosses 1 (PDF) (Report). Australian Biological Resources Study. Retrieved 22 August 2026.
  14. ↑ Flora of Australia, Volume 51: Mosses 1 (PDF) (Report). Australian Biological Resources Study. Retrieved 22 August 2026.
  15. ↑ "Plagiobryum demissum (Hook.) Lindb". GBIF. Retrieved 22 August 2026.
  16. ↑ "Plagiobryum Lindb". Integrated Taxonomic Information System. Retrieved 22 August 2026.
  17. ↑ Flora of Australia, Volume 51: Mosses 1 (PDF) (Report). Australian Biological Resources Study. Retrieved 22 August 2026.
  18. ↑ Spence, John R.; Ramsay, H. Peter (2002). "Phylogenetic relationships within the moss family Bryaceae based on chloroplast DNA evidence". Bryologist. Retrieved 22 August 2026.
  19. ↑ "Systematics and morphological evolution within the moss family Bryaceae: A comparison between parsimony and Bayesian methods for reconstruction of ancestral character states". Molecular Phylogenetics and Evolution. 2007. Retrieved 22 August 2026.
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