Wolf's spike-rush  (Eleocharis wolfii)

Wolf’s spike-rush has yet to be classified by the IUCN.

A small, grass-like plant, Wolf’s spike-rush (Eleocharis wolfii) can often be found growing in small tufts or clumps. The stems of Wolf’s spike-rush are blue-green, upright and usually very flat or even inrolled (2) (3) (4). The sides of the stems can be either smooth or marked with a number of ridges (2), and the leaf sheath at the base may be dark red, brown or straw-coloured (2) (3) (4).

Wolf’s spike-rush has small rhizomes that are light brown to white in colour (2). The flowers of this species are arranged spirally in an oval to lance-shaped group, or ‘spikelet’, at the end of the stem (2) (3). The flowers are covered in scales which can be dark red, orange-brown, straw coloured, or colourless, while the central vein of the scale can vary from orange-brown or straw-coloured to colourless (2).

The fruit of Wolf’s spike-rush is pear-shaped and is pale yellow, brown, grey or nearly white (2) (3). A small growth on the fruit, known as a tubercle, is pyramidal and brown (2).

Wolf’s spike-rush is widely distributed through central and eastern parts of North America (3). This species ranges from North Dakota, south to Texas and Louisiana in the United States (2) (4), while its eastern distribution includes Georgia and Virginia, with an introduced population present in New York (2). This species may also possibly occur as far north as Saskatchewan in Canada, although its presence here needs confirmation (2) (4).

With a preference for wet ground, Wolf’s spike-rush occurs in a wide variety of habitats, including marshes, swamps, ditches, the wet margins of rivers, ponds and lakes, wet depressions and short-term pools (2) (3).

While Wolf’s spike-rush may be found growing in a single-species group, it is more often found growing in clumps alongside a wide variety of other plants, with the associated plant community depending upon factors such as the soil type (2).

Wolf’s spike rush is a perennial species and requires high levels of light to produce seeds, with the flowering and fruiting season beginning in May and lasting until June (3). The flowers are wind-pollinated and the flower spikes tend to become detached after fruiting, with the stems then turning brown and withering (2). As well as producing seeds, Wolf’s spike-rush may also spread via new growth from the network of rhizomes at the base of the plant.

Like other plants, Wolf’s spike-rush uses photosynthesis to produce energy from the sun, with the main photosynthetic organs being the stems and leaf sheaths (3).

Although widely distributed, Wolf’s spike-rush is considered to be a rare and scattered species (2) (3) (4). There is currently limited information on the population size of Wolf’s spike-rush, although it is believed to be more common than once thought. However, in spite of the recent discovery of some new populations, a number of historical populations have vanished due to the conversion of natural habitat for agriculture and development (2).

The use of herbicides is known to be detrimental to Wolf’s spike-rush, as is the alteration of natural water cycles. Other possible threats include grazing by livestock and the potential future impacts of climate change, which could lead to an increase in the occurrence of drought (2).

Wolf’s spike-rush is considered to be a threatened species in many parts of the United States, with some states listing it as 'endangered'. While there may be separate legislation protecting this species in some states, there is no national legislation that provides any regulatory protection. Careful monitoring of this plant throughout its range is recommended, as is further research in order to properly estimate its population size as well as its biological requirements (2).

Suggested actions which may benefit Wolf’s spike-rush include the maintenance of its preferred habitat and the use of controlled burning to prevent the encroachment of woody vegetation (2).

Find out more about Wolf’s spike-rush:

• McKenzie, P.M., Witsell, C.T., Phillippe, L.R., Reid, C.S., Homoya, M.A., Rolfsmeier, S.B. and Morse, C.A. (2009)  Status assessment of Eleocharis wolfii (Cyperaceae) in the United States. Journal of the Botanical Research Institute of Texas, 3(2): 831-854. Available at:
  http://www.naturalheritage.com/!userfiles/Assmt_of_Eleocharis_wolfii_McKenzie_Witsell_et_al.pdf

Find out more about conservation in the Unites States:

• NatureServe:
  http://www.natureserve.org/