Juncus is a genus of monocotyledonous flowering plants, commonly known as rushes. It is the largest genus in the family Juncaceae, containing around 340 species.
Description
Rushes of the genus Juncus are herbaceous plants that superficially resemble grasses or sedges. They have historically received little attention from botanists; in his 1819 monograph, James Ebenezer Bicheno described the genus as "obscure and uninviting".
In Juncus section Juncotypus (formerly called Juncus subg. Genuini),
Distribution and ecology
Juncus has a cosmopolitan distribution, with species found throughout the world, with the exception of Antarctica.
Juncus species often prefer wetland habitats, such as salt marshes and seeps.
Juncus species are important members of the ecosystems they inhabit, providing food and creating habitat for many other organisms, including microbes, insects, amphibians, fish, and birds. Certain species have also been shown to alter the often heavily waterlogged soils they grow in around their roots, increasing the oxygen concentration and changing the pH. Beyond this, Juncus species across their range have been used in diverse ecological studies, including those relating to precipitation effects on marsh species, salt tolerance in brackish wetland plants, the effects of Juncus presence on plant diversity, and the effects of wetland plants on microbial soil communities.
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.
Uses
Species of genus Juncus are used by cultures around the world for various purposes. The fibrous stems lend themselves to making cordage, and cultures including indigenous peoples of California, South Africa, the Karabakh region, and pre-industrial Scandinavia have used this material to make baskets and candle wicks. There are also potential medical uses for Juncus, with both traditional medicinal uses from China and indigenous Americans as well as findings in modern medical science.
Classification
thumb|upright=0.9|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 '. The type species of the genus was designated by Frederick Vernon Coville, who in 1913 chose the first species in Linnaeus' account, Juncus acutus. Plants of the World Online accepts Juncinella but treats the others as synonyms of Juncus.
- Juncus subg. Juncus
- sect. Juncus
- sect. Graminei
- sect. Caespitosi
- sect. Stygiopsis
- sect. Ozophyllum
- sect. Iridifolii
- Juncus subg. Poiophylli
- sect. Tenageia
- sect. Steirochloa
- sect. Juncotypus
- sect. Forskalina
Species
As of July 2025, Plants of the World Online accepts 342 species: