Juncus

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Template:Short description Template:Automatic taxobox

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.[1]

Description

Rushes of the genus Juncus are herbaceous plants that superficially resemble grasses or sedges.[2] They have historically received little attention from botanists; in his 1819 monograph, James Ebenezer Bicheno described the genus as "obscure and uninviting".[3]

The form of the flower differentiates rushes from grasses or sedges. The flowers of Juncus comprise five whorls of floral parts: three sepals, three petals (or, taken together, six tepals), two to six stamens (in two whorls) and a stigma with three lobes.[2] The stems are round in cross-section, unlike those of sedges,[2] which are typically somewhat triangular in cross-section.[4]

In Juncus section Juncotypus (formerly called Juncus subg. Genuini),[5] 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.[6]

Distribution and ecology

Juncus has a cosmopolitan distribution, with species found throughout the world, with the exception of Antarctica.[1] They typically grow in cold or wet habitats, and in the tropics, are most common in montane environments.[2]

Fossil record

Several fossil fruits of a Juncus species have been described from middle Miocene strata of the Fasterholt area near Silkeborg in Central Jutland, Denmark.[7]

Classification

File:Juncus effuses Loch Kruse 7-8-08.jpg
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 Carl Linnaeus in his 1753 Script error: No such module "Lang".. The type species of the genus was designated by Frederick Vernon Coville, who in 1913 chose the first species in Linnaeus' account, Juncus acutus.[5] Juncus can be divided into two major groups, one group with cymose inflorescences that include bracteoles, and one with racemose inflorescences with no bracteoles.[5]

The genus is divided into the following subgenera and sections:[5]

  • 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

Template:Multiple image Plants of the World Online accepts the following species in the genus Juncus:[8] Template:Div col

Template:Div col end

References

Template:Reflist

Template:Taxonbar Template:Authority control

  1. ↑ a b Script error: No such module "citation/CS1".
  2. ↑ a b c d Script error: No such module "Citation/CS1".Template:Dead link
  3. ↑ Script error: No such module "Citation/CS1".
  4. ↑ Script error: No such module "citation/CS1".
  5. ↑ a b c d Script error: No such module "Citation/CS1".
  6. ↑ Script error: No such module "Citation/CS1".
  7. ↑ 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
  8. ↑ Script error: No such module "citation/CS1".
Retrieved from "http://debianws.lexgopc.com/wiki143/index.php?title=Juncus&oldid=592459"