Leersia

Leersia
	Rice Mercury ( Leersia oryzoides ), illustration
Systematics
	Commelinids
Order :	Sweet grass (Poales)
Family :	Sweet grasses (Poaceae)
Subfamily :	Ehrhartoideae
Tribe :	Oryzeae
Genre :	Leersia
Scientific name
	Leersia
	SW.

Leersia is a genus of the sweet grassfamily(Poaceae), whose representatives differ only slightly from representatives of the rice genus( Oryza ). The species are found worldwide in tropical to warm temperate areas. One of the 20 or so species, the rice mercury ( Leersia oryzoides ), is found in Europe.

description

The species of the genus Leersia are mostly perennial , rarely annual aquatic or marsh plants that form runners or rhizomes . The stalks are thin and 15 to 200 centimeters long. The lower part is creeping or floating, the upper part erect or ascending, with many, hairy and swollen nodes . The leaf blades are linear-lanceolate and grow almost without a leaf sheath directly on the stalk (kaulin). The ligule is membranous and ciliate. The inflorescences are panicles with mostly simple, grape-like side branches on short stems. The spikelets each carry only one floret and are elliptical to narrowly elongated, clearly flattened laterally and 1.5 to 8 millimeters long. They come off the stem easily and fall off as a whole. Glumes absent. The lemma is boat-shaped, keeled, paper-like to coarse, protruding five-nerved, with the external nerves interlocking with those of the palea. The keel of the lemma is scaly to comb-shaped ciliate, the upper end is pointed or beaked and usually awnless . The palea is similar to the lemma, but is narrower, the same length or longer, paper-like, three-nerved and has a ciliate keel. Two cavernous bodies and one, two, three or six stamens are formed per flower . The fruits are elongated, the embryo reaches about a third of the length of the fruit. The hilum is linear.

The basic chromosome number is x = 12.

distribution

The approximately 20 species are distributed in tropical to warm temperate zones around the world. One species, the rice mercury ( Leersia oryzoides ) occurs in Europe, eleven species in Africa, six species in North America, four in South America and four in China.

Leersia hexandra , inflorescence

Leersia virginica , inflorescence

Systematics and research history

Leersia is a genus from the family of grasses (Poaceae), there it is the subfamily Ehrhartoideae and tribe Oryzeae assigned. The genre was established in 1788 by Olof Peter Swartz . The generic name Leersia is reminiscent of the German pharmacist Johann Daniel Leers , (1727–1774). The genus differs from rice ( Oryza ) only in the lack of sterile covering scales . Synonyms of the genus are Aplexia Raf. , Asprella Schreb. , Blepharochloa Endl. , Ehrhartia F.H.Wigg. , Endodia Raf. , Homalocenchrus Mieg and Pseudoryza Griff.

About 20 species are assigned to the genus:

Leersia angustifolia Prodoehl : It occurs from Sudan to the Democratic Republic of the Congo.
Leersia denudata Launert : It occurs from Kenya to South Africa.
Leersia drepanothrix Stapf : It occurs from tropical West Africa to Uganda .
Leersia friesii Melderis : It occurs from southern Sudan to Botswana .
Leersia hexandra Sw. : It occurs in the tropics and subtropics.
Leersia japonica (Honda) Honda : It occurs from China and Japan to the temperate zones of East Asia.
Leersia lenticularis Michx. : It occurs in the central and eastern United States.
Leersia ligularis Trin. : It occurs in four varieties from Mexico to tropical America.
Leersia monandra Sw. : It occurs from Texas to Mexico, Florida and the Caribbean.
Leersia nematostachya Launert : It occurs in Cameroon , Angola and Zambia .
Leersia oncothrix C.E. Hubb . : It occurs in Zambia.
Rice Mercury ( Leersia oryzoides (L.) Sw. ): It occurs from the temperate zones of the northern hemisphere to northeast Mexico.
Leersia perrieri (A.Camus) Launert : It occurs in Madagascar.
Leersia sayanuka Ohwi : It occurs from central and southern China to Vietnam , southern Korea and Japan.
Leersia stipitata Bor : It occurs in Thailand.
Leersia tisserantii (A.Chev.) Launert : It occurs from tropical West Africa to Kenya and Namibia and in Guinea .
Leersia triandra C.E. Hubb. : It occurs from Sierra Leone to Liberia and in Cameroon.
Leersia virginica Willd. : It occurs from eastern Canada to the eastern and central United States.

Individual evidence

^ Illustration by Jan Kops (1765–1849) from Flora Batava of Afbeelding en Beschrijving van Nederlandsche Gewassen . 1849.
↑ ^a ^b ^c ^d Shou-liang Chen et al .: Leersia in Flora of China , Vol 22.
↑ ^a ^b W.D. Clayton, M. Vorontsova, KT Harman, H. Williamson: Leersia. In: GrassBase - The Online World Grass Flora. Royal Botanic Gardens, Kew, accessed November 2, 2014 .
^ ^A ^b Leersia in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland.
↑ Leersia. In: The International Plant Name Index. Retrieved November 2, 2014 .
↑ Leersia. In: Compact lexicon of biology at Spektrum.de . Retrieved November 8, 2014 .
↑ Leersia. In: The Plant List. Retrieved November 2, 2014 .
↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r Rafaël Govaerts (Ed.): Leersia. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved October 30, 2016.
↑ German name after Aichele, Schwegler: Our grasses . Over 400 color drawings. Updated 12th edition. Franckh-Kosmos, Stuttgart 2011, ISBN 978-3-440-12573-1 , p. 100 .

Web links

Commons : Leersia - collection of images, videos and audio files

WD Clayton, M. Vorontsova, KT Harman, H. Williamson: Leersia. In: GrassBase - The Online World Grass Flora. Royal Botanic Gardens, Kew, accessed November 2, 2014 .
Wu Zheng-yi, Peter H. Raven, Deyuan Hong (Eds.): Flora of China . Volume 22: Poaceae . Science Press / Missouri Botanical Garden Press, Beijing / St. Louis 2006, ISBN 1-930723-50-4 , pp. 184 (English, online ).

[Illustration-1] Illustration by Jan Kops (1765–1849) from Flora Batava of Afbeelding en Beschrijving van Nederlandsche Gewassen . 1849.

[FoC-2] Shou-liang Chen et al .: Leersia in Flora of China , Vol 22.

[grassbase-3] W.D. Clayton, M. Vorontsova, KT Harman, H. Williamson: Leersia. In: GrassBase - The Online World Grass Flora. Royal Botanic Gardens, Kew, accessed November 2, 2014 .

[GRIN-4] A ^b Leersia in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland.

[IPNI-5] Leersia. In: The International Plant Name Index. Retrieved November 2, 2014 .

[spektrum-6] Leersia. In: Compact lexicon of biology at Spektrum.de . Retrieved November 8, 2014 .

[PlantList-7] Leersia. In: The Plant List. Retrieved November 2, 2014 .

[WCSP-8] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r Rafaël Govaerts (Ed.): Leersia. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved October 30, 2016.

[deutsch-9] German name after Aichele, Schwegler: Our grasses . Over 400 color drawings. Updated 12th edition. Franckh-Kosmos, Stuttgart 2011, ISBN 978-3-440-12573-1 , p. 100 .