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Genus of flowering plants in the rush family Juncaceae From Wikipedia, the free encyclopedia
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]
Juncus | |
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Habit of J. conglomeratus | |
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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 ![]() | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Clade: | Commelinids |
Order: | Poales |
Family: | Juncaceae |
Genus: | Juncus L. |
Type species | |
Juncus acutus | |
Synonyms[1] | |
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Rushes of the genus Juncus are herbaceous plants that superficially resemble grasses or 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 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.[3] The stems are round in cross-section, unlike those of 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]
Juncus has a cosmopolitan distribution, with species found throughout the world, with the exception of Antarctica.[2] They typically grow in cold or wet habitats, and in the tropics, are most common in montane environments.[3]
Several fossil fruits of a Juncus species have been described from middle Miocene strata of the Fasterholt area near Silkeborg in Central Jutland, Denmark.[8]
The genus Juncus was first named by Carl Linnaeus in his 1753 Species Plantarum. The type species of the genus was designated by Frederick Vernon Coville, who in 1913 chose the first species in Linnaeus' account, Juncus acutus.[6] Juncus can be divided into two major groups, one group with cymose inflorescences that include bracteoles, and one with racemose inflorescences with no bracteoles.[6]
The genus is divided into the following subgenera and sections:[6]
Plants of the World Online accepts the following species in the genus Juncus:[9]