Swordleaf rush

Description

Juncus ensifolius is a species of rush known by the common names swordleaf rush, sword-leaved rush, and three-stamened rush. It is native to much of western North America from Alaska to central Mexico, and into eastern Canada. It is present in Japan and far eastern Russia, and it has been introduced to many other regions of the world, including Europe, New Zealand, Hawaii, and Australia. It is a plant of wet areas in many types of habitat. This is a rhizomatous perennial herb forming clumps of stems 20 to 60 centimeters tall. The flat but curving leaves are mostly located at the base of the stems and are variable in length. The inflorescence is an array of many rounded clusters of many flowers each. Each flower has a number of dark brown to black tepals a few millimeters long and usually three small stamens enclosed between them. The fruit is an oblong capsule with a small beak on the tip. 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. 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". 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. The stems are round in cross-section, unlike those of sedges, which are typically somewhat triangular in cross-section. In Juncus section Juncotypus (formerly called Juncus subg. Genuini), 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. Juncus has a cosmopolitan distribution, with species found throughout the world, with the exception of Antarctica. They typically grow in cold or wet habitats, and in the tropics, are most common in montane environments. Several fossil fruits of a Juncus species have been described from middle Miocene strata of the Fasterholt area near Silkeborg in Central Jutland, Denmark.