Spiny Rush

Juncus acutus

large bush with string-like stems
East Basin, south side | February 2018

Spiny rush (Juncus acutus) is an eye-catching plant – a four foot hedgehog with needle-like spines. It is found along the upper parts of the salt marsh west of Interstate 5 and the alkali marsh to the east. The cylindrical, sharply pointed leaves grow from the base outward in all directions, while the mahogany clusters of seed capsules make conspicuous tassels.

For centuries, the Kumeyaay have gathered, dried and split the leaves and used them to weave their traditional baskets. When used without dye, spiny rush is pale tan. Colored patterns are made by weaving in other materials or by dying the leaves black or bleaching them white.

Other Common Names:

Leopold's rush, spike rush, southwestern spiny rush, sharp-leaved rush, sharp rush

Description 4,11,34,400,403

Spiny rush is a grass-like, evergreen perennial that may reach three or four feet (1-1.2 m) in height. The most conspicuous feature is its “hedgehog,” or sea urchin, appearance, with a dense tuft of long leaves ascending and spreading from a short, subsurface rhizome. Cylindrical leaves are smooth, sharply pointed at the ends and form a sheath around the bases of the flowering stems.

Flowers are born in compound clusters on long, stiff, unbranched stems that resemble the leaves.  Clusters appear to be lateral near stem ends, but actually, they are terminal; what appears to be a continuation of the stem to a sharp point, is actually a modified leaf (bract) that sheaths the top of the stem immediately below the flower cluster. Within a cluster are a few to many smaller clusters, each with one to six flowers. Cluster branchlets are subtended by small, leaf-like bracts. The inconspicuous flowers of spiny rush are bisexual and consist of three sepals and three similar petals (together called tepals), six stamens and a pistil. Tepals are green, aging to reddish or brown. Stamens are about as long as the tepals with pale yellow-green, flattened anthers. The pistil has a globular, superior, six-lobed ovary and a three-branched, red style each branch terminating in an undifferentiated stigma. Flowers open May into August1 while well within the cluster of leaves, and stems continue to elongate as fruits mature.

Conspicuous clusters of mahogany capsules develop following fertilization and ride like tassels near the tops of the leaves. Capsules are nearly spherical, with a small point, about 1/4 inch (0.6 cm) long. Each capsule opens from the end into three valves, releasing numerous small seeds, < 1/16 inch (0.1 cm) long. Opened capsules remain on the plant for many months.

tiny seed pods clumped together on stem

Maturing capsules | East Basin, south side | July 2010

large bush with string-like stems

Central Basin, south side | November 2009

cluster of small flowers on top of stem

Image credit: Barbara Wallach | Open flowers | Trail between Santa Carina and Santa Helena | April 2017

Distribution 7,89,172

Spiny rush is a nearly cosmopolitan species, native to western and southern Europe, western Asia, northern Africa and areas of South American as well as in southwestern United States and Mexico. It has been introduced into areas of New Zealand and Australia where it has become a serious environmental pest.404

In California, the spiny rush is found primarily along the coast from San Luis Opisbo county south into Baja California, and east into Imperial and Riverside counties, below 3,000 feet (950 m). It is a plant of damp areas, tolerant of both saline and alkaline conditions, usually found in coastal areas, such as upper salt marshes and dunes and in inland areas, such as alkaline seeps and damp meadows.

The California population of spiny rush is threatened by habitat loss due to urbanization and flood control. However, on a worldwide basis, the species appears to be secure.45,172

In the Reserve, spiny rush may be found sporadically on either side of the freeway, especially on the south side, wherever trails run close to the water.

Classification 15,75,272

Spiny rush is a monocot angiosperm in the rush family (Juncaceae), a large family of eight genera and more than 400 species.41Rushes resemble grasses (Poaceae) and sedges (Cyperaceae), from which they can be told by the presence of small sepals and petals (tepals), which are absent in grasses and sedges, and by characteristics of the fruit and seed.2,11 The old hint “Sedges have edges and rushes are round.”100 is a useful clue to the leaves.

In California, there are only two genera in the rush family. Juncus is by far the larger with 70 species found in California, of which 58 are native. A total of six species of rush have been reported from the Reserve. Confusingly, bulrushes (Schoenoplectus spp.) are not rushes but are instead in the sedge family.2

Our spiny rush is subspecies leopoldii. There are 26 previously described subspecies, varieties and forms of this species, of which only two are currently recognized. J. acutus ssp leopoldii is the only one in North America.67

Jepson eFlora Taxon Page
thin stem with flower cluster on top

Central Basin, south side | May 2018

mini seed pod with flower blooming

Two flowers. Clockwise from top, lines indicate style, anther, and tepal | East Basin, south side | May 2018

tiny seed pod with mini seeds outside of it

Capsule shedding tiny seeds | East Basin, south side | June 2018


Spiny rush generally occupies a narrow band around the uppermost fringe of a salt marsh, where both inundation times and soil salinity are reduced.407,408 However, in spite of its association with the salt marsh, spiny rush both germinates and grows better in the absence of salt.409 Like some other salt marsh species410 the lower boundary of spiny rush may be determined by increasing soil salinity while the upper boundary, where salts are reduced, is restricted by competition with less salt-tolerant species of the sage scrub.

It has been suggested that spiny rush once formed conspicuous boundaries around Southern California salt marshes, and that many of today’s plants are remnants of that earlier population, marking the boundaries of previous marshes rather than tracking the current edges.34,407

small flowers on end of stem

Cluster with open flowers | East Basin, south side | May 2018

small flowers on end of stem

Developing flower cluster | Central Basin, south side | April 2018

large bush with string-like stems

Central Basin, south side | January 2010

Human Uses  

Spiny rush was one of several plants used by local Native Americans in their basketry. The relative importance of spiny rush, the specific use, and the construction varied among tribes.

Traditionally, rushes were harvested, split lengthwise and dried until bleached from dark green to a golden tan or pale sand. The dry, inner, pithy material was scraped off and if desired, the strands were dyed. Black was achieved by burying in a muck of mud and decaying plant material, or by dying with a solution of elderberry stems and leaves,34,406 while white was achieved by gentle heating and blanching. An important shade of red-brown was obtained from the natural color at the base of basket rush (Juncus textilis). The colored stems were used to weave in the traditional patterns, such as the rattlesnake design that was inserted to warn mice away from the baskets.406

In the 19th century, the primary use of baskets began to change from utilitarian to sale on the commercial market,75,272 and the baskets became known as the Mission Indian style.

In a sense, artfully made baskets linking with the past and creating a modern identity may be seen as the transcending
survival skill. It is difficult to imagine basketry as it must have been, as something varied and
beautiful but just as often practical, arising in response to a naturally evolving world.


large bush with string-like stems

Central Basin, south side | May 2018

tiny flowers on end of spiked thin stem

Cluster with open flowers | Central Basin, south side | May 2018

small thin stem leaves just planted

La Orilla revegetation site | January 2018

Interesting Facts 21,291

The genus name, Juncus, is thought to some from classical Latin, jungere, which means “to join or bind” because the stems and leaves were used for weaving or binding. Not a surprising etymology.

However, the name for the perky little feeder bird, the Junco, also comes from jungere. It was probably first applied as a name for a European species known as a reed-sparrow and later to the group of finches.

Also, “jonquil”, a name for a type of narcissus or daffodil, may also share the same etymology, reflecting the shape of its leaves.

Finally the word “junket” may have started out asjonquet” or “fish basket” – a basket in which fish were captured or transported. The word then evolved into a picnic basket then a pleasure trip and finally a pleasure trip by a government official at taxpayer expense.

single long sharp stem

East Basin, south side | September 2016

large bush with string-like stems

Central Basin, south side | May 2017

large bush with string-like stems in a field by a river

Photo credit: Denise Stillinger | Central Basin, south side

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