Juncus effusus is a perennial herbaceous flowering plant species in the rush family Juncaceae, with the common names common rush or soft rush.
Distribution and habitat
Juncus effusus has a wide distribution, considered native in Europe, Asia, Africa, Madagascar, North America, and South America. It has naturalized in Australia, New Zealand, South Africa and various oceanic islands.
It grows in wet areas, such as wetlands, riparian areas, and marshes with sandy and peaty substrates. It is common throughout the British Isles by rivers, streams and lakes, in wet heathland and pastures, including purple moor-grass and rush pastures and fen-meadow plant associations.
Description
Juncus effusus grows in large clumps up to about 1.2 metres (3 ft 11 in) tall. The stems are smooth cylinders with light pith filling. The yellowish inflorescence appears to emerge from one side of the stem about 20 centimetres (8 in) from the top. In fact the stem ends there; the top part is the bract, that continues with only a slight colour-band marking it from the stem. The lower leaves are reduced to a brown sheath at the bottom of the stem.
Five subspecies are currently recognized:
Juncus effusus subsp. austrocalifornicus Lint — endemic to California and Baja California.
Juncus effusus subsp. effusus — widespread
Juncus effusus subsp. laxus (Robyns & Tournay) Snogerup — tropical Africa, Madagascar, Mauritius, Canary Islands, Madeira.
Juncus effusus subsp. pacificus (Fernald & Wiegand) Piper & Beattie — Alaska, British Columbia, Washington, Idaho, Oregon, California, Baja California.
Juncus effusus subsp. solutus (Fernald & Wiegand) Hämet-Ahti — central and eastern United States.
Juncus effusus can be differentiated from the rarer Juncus pylaei by the number of ridges on the stem. Juncus effusus has 30 to 40 ridges and J. pylaei has 10 to 20.
