Eleocharis

Taxobox
name = "Eleocharis"

---

image_width = 240px
image_caption = water chestnut
regnum = Plantae
divisio = Magnoliophyta
classis = Liliopsida
ordo = Poales
familia = Cyperaceae
genus = "Eleocharis"
genus_authority = R. Br.

"Eleocharis" is a genus of 250 or more species the Cyperaceae (sedge family). They are known commonly as spikerushes, although spikesedges is a more technically appropriate name and most scientists who study them in earnest refer to them as such. The genus has a geographically cosmopolitan distribution, with centers of diversity in the Amazon and adjacent eastern slopes of the South American Andes, northern Australia, eastern North America, California, Southern Africa, and subtropical Asia. The vast majority of Eleocharis species grow in aquatic or mesic habitats from sea level to higher than 5,000 meters in elevation (in the tropical Andes).

The genus itself is relatively easy to recognize; all Eleocharis species have photosynthetic stems and lack leaves (the leaves have been reduced to sheaths surrounding the base of the stems). Many species are robust, rhizomatously-spreading plants of lowland tropical wetlands, while many others are small caespitose annual or perennial herbs growing near streams, and still others are intermediate. There are also a number of species that are obligate aquatic species, which usually have submerged, branching stems and often exhibit interesting photosynthetic adaptations, such as the ability to switch between C3 and C4 types of photosynthesis in response to different environmental stimuli. In all Eleocharis species, the flowers are borne on unbranched terminal spikelets at the apices of stems.

In spite of the diversity of the genus itself, taxonomic characters useful for delimiting species within it are few and many species are very difficult to tell apart. Many currently recognized species with very wide geographic ranges are highly polymorphic. Some of these species probably contain multiple independently-evolving lineages. Because of their difficult nature, many botanists avoid collecting these plants and so many species are under-represented in the botanical record.

One of the best known species is the Chinese water chestnut, "Eleocharis dulcis". These plants bear tubers on their rhizomes which may be peeled and eaten raw or boiled. In Australia, magpie geese rely almost exclusively on these tubers for sustenance for a significant portion of the year.

Selected species:
*"Eleocharis acicularis" - needle spikerush; dwarf hairgrass
*"Eleocharis atropurpurea" - purple spikerush
*"Eleocharis bella" - beautiful spikerush
*"Eleocharis cellulosa" - coastal spikerush, Gulf Coast spikerush
*"Eleocharis compressa" - flatstem spikerush
*"Eleocharis geniculata" - Canada spikesedge
*"Eleocharis macrostachya" - pale spikerush
*"Eleocharis montevidensis" - sand spikerush
*"Eleocharis mutata" - scallion grass
*"Eleocharis obtusa" - blunt spikerush
*"Eleocharis pachycarpa" - black sand spikerush
*"Eleocharis pachystyla" - false junco
*"Eleocharis palustris" - common spikerush
*"Eleocharis parvula" - dwarf spikerush
*"Eleocharis quadrangulata" - squarestem spikerush
*"Eleocharis quinqueflora" - fewflower spikerush
*"Eleocharis radicans" - rooted spikerush
*"Eleocharis rostellata" - beaked spikerush
*"Eleocharis tenuis" - slender spikerush
*"Eleocharis vivipara" - umbrella hairgrass

External links

* [http://plants.usda.gov/java/profile?symbol=ELEOC USDA Plants Profile: North American Species]
* [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=111420 eFloras Profile]
* [http://www.amjbot.org/cgi/content/full/93/5/707 Baksh & Richards (2006) An architectural model for "Eleocharis": morphology and development of "Eleocharis cellulosa" (Cyperaceae). "Am J Botany" 93:707-15.]

* [http://www.wetwebmedia.com/plantedtkssubwebindex/eleocharis.htm Hairgrass]
* [http://www.botany.com/eleocharis.html Botany.com]

*Rataj, Karel. 1977. Aquarium plants; hair grass. TFH 12/77.