Juncus

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Juncus
Habit of J. conglomeratus
Flower of J. squarrosus showing: 6 spreading tepals, anthers (upright yellow, held on white filaments), ovary (green) with stigma (pinkish tip column) and styles (white)
Scientific classification Edit 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]
  • Cephaloxys Desv.,
    illegitimate superfluous name
  • Tristemon Raf. 1838, illegitimate homonym, not Raf. 1819 (Juncaginaceae) nor Klotzsch 1838 (syn of Erica in Ericaceae) nor Scheele 1848 (syn of Cucurbita in Cucurbitaceae)
  • Juncastrum Fourr., not validly published
  • Juncinella Fourr., not validly published
  • Phylloschoenus Fourr., not validly published
  • Tenageia (Dumort.) Fourr.
  • Microschoenus C.B.Clarke

Juncus is a genus of monocotyledonous flowering plants, commonly known as rushes. It is the largest genus in the family Juncaceae, containing around 300 species.[2]

Description

Rushes of the genus Juncus are

sedges.[3] They have historically received little attention from botanists; in his 1819 monograph, James Ebenezer Bicheno described the genus as "obscure and uninviting".[4]

The form of the flower differentiates rushes from grasses or sedges. The flowers of Juncus comprise five

sedges,[3] which are typically somewhat triangular in cross-section.[5]

In Juncus section Juncotypus (formerly called Juncus subg. 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 the bract subtending the inflorescence closely resembles a continuation of the stem, giving the appearance that the inflorescence is lateral.[7]

Distribution and ecology

Juncus has a

montane environments.[3]

Fossil record

Several

strata of the Fasterholt area near Silkeborg in Central Jutland, Denmark.[8]

Classification

In Juncus effusus (and other species in J. sect. Juncotypus), the bract appears as a continuation of the stem, and the inflorescence appears lateral.

The genus Juncus was first named by

bracteoles, and one with racemose inflorescences with no bracteoles.[6]

The genus is divided into the following subgenera and sections:[6]

  • Juncus subg. Juncus
    • sect. Juncus
    • sect. Graminei (Engelm.) Engelm.
    • sect. Caespitosi Cout.
    • sect. Stygiopsis Kuntze
    • sect. Ozophyllum Dumort.
    • sect. Iridifolii Snogerup & Kirschner
  • Juncus subg. Poiophylli Buchenau
    • sect. Tenageia Dumort.
    • sect. Steirochloa Griseb.
    • sect. Juncotypus Dumort.
    • sect. Forskalina Kuntze

Species

Selected Juncus species
J. inflexus
J. jacquinii
J. squarrosus
J. trifidus

Plants of the World Online accepts the following species in the genus Juncus:[9]

References

  1. ^ Kew World Checklist of Selected Plant Families
  2. ^
    ISBN 0-19-513729-9
    .
  3. ^ a b c d D. M. D. Yakandawala; U. M. Sirisena; M. D. Dassanayake (2005). "Two new records of Juncus species (rush family – Juncaceae) in Sri Lanka" (PDF). Ceylon Journal of Science. 33: 67–76.
  4. doi:10.1111/j.1095-8339.1817.tb00229.x
    .
  5. ISBN 978-0-19-515207-4
    .
  6. ^
    S2CID 31779452
    .
  7. doi:10.7751/telopea20013009
    .
  8. ^ Angiosperm Fruits and Seeds from the Middle Miocene of Jutland (Denmark) by Else Marie Friis, The Royal Danish Academy of Sciences and Letters 24:3, 1985
  9. ^ "Juncus L." Plants of the World Online. Board of Trustees of the Royal Botanic Gardens, Kew. 2017. Retrieved 22 January 2021.
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