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''Eleocharis'' is a virtually cosmopolitan genus of 250 or more species of flowering plants in the sedge family, Cyperaceae.〔(Kew World Checklist of Selected Plant Families )〕 The name is derived from the Greek words ἕλειος (''heleios''), meaning "marsh dweller," and χάρις (''charis''), meaning "grace."〔 〕 Members of the genus are known commonly as spikerushes or spikesedges. The genus has a geographically cosmopolitan distribution, with centers of diversity in the Amazon Rainforest 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).〔Govaerts, R. & Simpson, D.A. (2007). World Checklist of Cyperaceae. Sedges: 1-765. The Board of Trustees of the Royal Botanic Gardens, Kew. 〕 The genus itself is relatively easy to recognize; all ''Eleocharis'' species have photosynthetic stems but no green 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 carbon fixation in response to different environmental stimuli. In all ''Eleocharis'' species, the flowers are borne on unbranched terminal spikelets at the apices of stems.〔(Flora of North America, Vol. 23 Page 4, 6, 7, 29, 60, ''Eleocharis'' R. Brown, Prodr. 224. 1810. )〕〔(Flora of China, Vol. 23 Page 188, 荸荠属 bi qi shu, ''Eleocharis'' R. Brown, Prodr. 224. 1810. )〕〔(Altervista Flora Italiana, genere Eleocharis ) includes photos plus distribution maps for Europe and sometimes for North America〕〔(Biota of North America Program, 2013 county distribution maps for US and Canadian species )〕 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'' (L.) Roem. & Schult. – needle spikerush; dwarf hairgrass *''Eleocharis acutangula'' (Roxb.) Schult. *''Eleocharis afflata'' Steud. *''Eleocharis atropurpurea'' (Retz.) J.Presl & C.Presl – purple spikerush *''Eleocharis baldwinii'' (Torr.) Chapm. *''Eleocharis bella'' (Piper) Svenson – beautiful spikerush *''Eleocharis bifida'' S.G. Smith glade spikerush *''Eleocharis bolanderi'' A.Gray – Bolander's spikerush *''Eleocharis brittonii'' Svenson ex Small *''Eleocharis cellulosa'' Torr. – coastal spikerush, Gulf Coast spikerush *''Eleocharis compressa'' Sull. – flatstem spikerush *''Eleocharis congesta'' D.Don *''Eleocharis dulcis'' (Burm.f.) Trin. ex Hensch. – Chinese water chestnut *''Eleocharis elegans'' (Kunth) Roem. & Schult. *''Eleocharis equisetoides'' (Elliott) Torr. *''Eleocharis filiculmis'' Kunth *''Eleocharis geniculata'' (L.) Roem. & Schult. – Canada spikesedge *''Eleocharis halophila'' Fernald & Brackett – saltmarsh spikerush *''Eleocharis kuroguwai'' Ohwi *''Eleocharis macrostachya'' Britton – pale spikerush *''Eleocharis montana'' (Kunth) Roem. & Schult. *''Eleocharis montevidensis'' Kunth – sand spikerush *''Eleocharis mutata'' (L.) Roem. & Schult. – scallion grass *''Eleocharis nodulosa'' Schult. *''Eleocharis obtusa'' (Willd.) Schult. – blunt spikerush *''Eleocharis pachycarpa'' Desv. – black sand spikerush *''Eleocharis pachystyla'' (C.Wright) C.B.Clarke – false junco *''Eleocharis palustris'' (L.) Roem. & Schult. – common spikerush *''Eleocharis parishii'' Britton – Parish's spikerush *''Eleocharis parvula'' (Roem. & Schult.) Link ex Bluff et al. – dwarf spikerush, hairgrass *''Eleocharis pellucida'' J.Presl & C.Presl *''Eleocharis quadrangulata'' (Michx.) Roem. – squarestem spikerush *''Eleocharis quinqueflora'' (Hartmann) O.Schwarz – fewflower spikerush *''Eleocharis radicans'' (A.Dietr.) Kunth – rooted spikerush *''Eleocharis rostellata'' (Torr.) Torr. – beaked spikerush *''Eleocharis sellowiana'' Kunth *''Eleocharis tenuis'' (Willd.) Schult. – slender spikerush *''Eleocharis torticulmis'' S.G.Sm. – twist-stem spikerush *''Eleocharis tortilis'' (Link) Schult. – twisted spikerush *''Eleocharis tuberculosa '' (Michx.) Roem. & Schult. *''Eleocharis uniglumis'' (Link) (Link) Schult., 1824 *''Eleocharis vivipara'' Link – umbrella hairgrass 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Eleocharis」の詳細全文を読む スポンサード リンク
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