Wikipedia

Juncus

Juncusis agenusofmonocotyledonousflowering plants,commonly known asrushes.It is the largest genus in the familyJuncaceae,containing around 300 species.[2]

Juncus
Habit ofJ. conglomeratus
Flower ofJ. squarrosusshowing: 6 spreading tepals, anthers (upright yellow, held on white filaments), ovary (green) with stigma (pinkish tip column) and styles (white)
Scientific classificationEdit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Poales
Family: Juncaceae
Genus: Juncus
L.
Type species
Juncus acutus
Synonyms[1]

Description

edit

Rushes of the genusJuncusareherbaceousplants that superficially resemblegrassesorsedges.[3]They have historically received little attention from botanists; in his 1819monograph,James Ebenezer Bichenodescribed the genus as "obscure and uninviting".[4]

The form of the flower differentiates rushes from grasses or sedges. The flowers ofJuncuscomprise fivewhorlsof floral parts: three sepals, three petals (or, taken together, six tepals), two to sixstamens(in two whorls) and astigmawith three lobes.[3]The stems are round in cross-section, unlike those ofsedges,[3]which are typically somewhat triangular in cross-section.[5]

InJuncussectionJuncotypus(formerly calledJuncussubg.Genuini),[6]which contains some of the most widespread and familiar species, the leaves are reduced to sheaths around the base of the stem and thebractsubtending the inflorescence closely resembles a continuation of the stem, giving the appearance that the inflorescence is lateral.[7]

Distribution and ecology

edit

Juncushas acosmopolitan distribution,with species found throughout the world, with the exception ofAntarctica.[2]They typically grow in cold or wet habitats, and in the tropics, are most common inmontaneenvironments.[3]

Fossil record

edit

Severalfossilfruits of aJuncusspecies have been described frommiddle Miocenestrataof the Fasterholt area nearSilkeborgin CentralJutland,Denmark.[8]

Classification

edit
InJuncus effusus(and other species inJ.sect.Juncotypus), the bract appears as a continuation of the stem, and the inflorescence appears lateral.

The genusJuncuswas first named byCarl Linnaeusin his 1753Species Plantarum.Thetype speciesof the genus was designated byFrederick Vernon Coville,who in 1913 chose the first species in Linnaeus' account,Juncus acutus.[6]Juncuscan be divided into two major groups, one group withcymoseinflorescencesthat includebracteoles,and one withracemoseinflorescences with no bracteoles.[6]

The genus is divided into the followingsubgeneraandsections:[6]

  • Juncussubg.Juncus
    • sect.Juncus
    • sect.Graminei(Engelm.) Engelm.
    • sect.CaespitosiCout.
    • sect.StygiopsisKuntze
    • sect.OzophyllumDumort.
    • sect.IridifoliiSnogerup & Kirschner
  • Juncussubg.PoiophylliBuchenau
    • sect.TenageiaDumort.
    • sect.SteirochloaGriseb.
    • sect.JuncotypusDumort.
    • sect.ForskalinaKuntze

Species

edit
SelectedJuncusspecies
J. inflexus
J. jacquinii
J. squarrosus
J. trifidus

Plants of the World Onlineaccepts the following species in the genusJuncus:[9]

References

edit
  1. ^Kew World Checklist of Selected Plant Families
  2. ^abRalph E. Brooks; Steven E. Clemants (2000)."Juncus".Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae.Flora of North America.Vol. 22.Oxford University Press.ISBN0-19-513729-9.
  3. ^abcdD. M. D. Yakandawala; U. M. Sirisena; M. D. Dassanayake (2005)."Two new records ofJuncusspecies (rush family – Juncaceae) in Sri Lanka "(PDF).Ceylon Journal of Science.33:67–76.
  4. ^James Ebenezer Bicheno(1819)."XVII. Observations on the Linnean genusJuncus,with the characters of those species, which have been found growing wild in Great Britain ".Transactions of the Linnean Society of London.12(2): 291–337.doi:10.1111/j.1095-8339.1817.tb00229.x.
  5. ^Peter W. Ball; A. A. Reznicek; David F. Murray."210. Cyperaceae Jussieu".In Flora of North America Committee (ed.).Magnoliophyta: Commelinidae (in part): Cyperaceae.Flora of North America.Vol. 23.Oxford University Press.ISBN978-0-19-515207-4.
  6. ^abcdJan Kirschner; Lázaro J. Novara; Vladimir S. Novikov; Sven Snogerup; Zdeněk Kaplan (1999). "Supraspecific division of the genusJuncus(Juncaceae) ".Folia Geobotanica.34(3): 377–390.Bibcode:1999FolGe..34..377K.doi:10.1007/BF02912822.JSTOR4201385.S2CID31779452.
  7. ^K. L. Wilson; L. A. S. Johnson (2001)."The genusJuncus(Juncaceae) in Malesia and allied septate-leaved species in adjoining regions ".Telopea.9(2): 357–397.doi:10.7751/telopea20013009.
  8. ^Angiosperm Fruits and Seeds from the Middle Miocene of Jutland (Denmark) byElse Marie Friis,The Royal Danish Academy of Sciences and Letters 24:3, 1985
  9. ^"JuncusL. "Plants of the World Online.Board of Trustees of the Royal Botanic Gardens, Kew. 2017.Retrieved22 January2021.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Juncus&oldid=1237670949"