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Revision of two Elymus species (Poaceae)


Elymus L. is the largest genus in the tribe Triticeae Dumort., encompassing approxi-
mately 150 species over the world. Species of the genus are widely distributed in the temperate re-
gions, particularly in the northern hemisphere. China is one of the most important world’s distribu-
tion and diversification centers of the Elymus species, with more than 80 taxa (including those clas-
sifted in the genus Roegneria C. Koch) widely occurring in many provinces, particularly in the
western and northern regions of the country. Owing to its abundance in species, extensive distribu-
tion, variable habitats, and complicated morphological variation, taxonomic classification of this ge-
nus has been always problematic. In addition, many traditional taxonomists from different parts of
the world mainly had their research interests in their own regions due to historical reasons, which
largely hampered communication between the regions. As a consequence, some Elymus species were-
described as new species several times by different taxonomists. The present paper reports taxonomic
revision of two common Elymus species, i.e.E. antiquus and E. burchan-buddae. Elymus an-
tiquus is a perennial and tetraploid (2n= 4x= 28) species containing the StStYY genomes. It is
commonly found in western and northwestern China and is also found in mountain area of Nepal.
This species was first described by a Russian agrostologist, S. A. Nevski, based on specimens col-
lected from Tibet, China. Our study indicated that two grass species described as Agropyron microl-
epis Melderis from Nepal and Roegneria parvigluma Keng from Kangding of Sichuan are the syn-
onyms of E. antiquus. Elymus burchan-buddae is also a perennial and tetraploid (2n = 4x = 28)
species containing the StStYY genomes. It is widely distributed in western and northwestern China
and might have its distribution in Nepal and northern India. This species was first described by
Nevski based on specimens collected from Burchan Budai Shan (Kunlun Mountain) in Qinghai. Our
investigation concluded that two species described as Agropyron nutans Keng from Xiahe of Gansu
and Agropyron breviglumis Keng from Shao Wu Shi of Sichuan are the synonyms of E. burchan-
buddae.


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