Once dismissed as obscure and uninviting, rushes quietly clean polluted water
In 1819 a botanist wrote off the rush genus Juncus as dull. Two centuries later these grass-like wetland plants look far more interesting: they grow on every continent but Antarctica, oxygenate waterlogged soil around their roots, feed fish and birds, and may help scrub contaminants from dirty water.
Juncus is the largest genus in the rush family, with around 340 species; Plants of the World Online accepted 342 as of July 2025. James Ebenezer Bicheno's unflattering 1819 verdict reflected how little attention botanists paid them. At a glance rushes resemble grasses or sedges, but the flower gives them away, with six tepals, two to six stamens and a three-lobed stigma. Rolling a stem between your fingers helps too: rush stems are round, while sedges tend toward a triangular cross-section.
In some of the most familiar species the leaves shrink to sheaths at the stem base, and the bract beneath the flower cluster looks just like more stem, so the flowers seem to sprout from the side. Rushes favour cold or wet places, and in the tropics they mostly live on mountains. They are usually described as wind-pollinated, though some species may get partial help from insects.
Their preference for salt marshes and seeps brings them into contact with waterborne pollutants, and research suggests deliberate planting could help clean contaminated water biologically. Certain species raise oxygen levels and shift the pH of the soggy soil around their roots. Ecologists use them widely, from salt-tolerance experiments to studies of soil microbes. Fossil fruits from the middle Miocene have turned up near Silkeborg in Denmark.
People from California to South Africa and pre-industrial Scandinavia have twisted the fibrous stems into cordage, baskets and candle wicks. Carl Linnaeus named the genus in 1753, and in 1913 Frederick Coville fixed Juncus acutus as its type. The family tree is still being redrawn: a 2022 analysis by Viktorie Brožová and colleagues found the genus paraphyletic and proposed six new genera, though only one, Juncinella, had wide acceptance by 2025. Juncus tenuis, a clumping weed 15 to 60 centimetres tall, goes by names such as path rush and poverty rush.
Source: Juncus
