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Genomic constitution

St - This is the most widespread genome in the Triticeae. The species in which it is the only genome are not particularly abundant, but species in which the St genome is combined with one or more other genomes are numerous and widely distributed. See, for example, Anthosachne, Campeiostachys, Douglasdeweya, Elymus, Kengyilia, and Roegneria.

Distinguishing features

Plants perennial. Inflorescences with a touch rachis and solitary spikelets; middle internodes only slightly shorter than the spikelets. Spikelets truly sessile or on pedicels up to 0.3 mm long. Anthers more than 3 mm long.



Plants perennial, not or only shortly rhizomatous. Culms 35-110 cm tall, lowest internode 0.5-1.8 mm thick.

Leaves 1–7 mm wide, ribs prominent on upper surface.

Inflorescence spikelike, rachis tough, with solitary spikelets; lowest internode and middle internodes similar in length, 7–16 mm.

Spikelets solitary, tangential to the rachis, 10–16 mm long, those at mid-inflorescence shorter than to slightly longer than the adjacent internode, not pedicellate or pedicels up to 0.3 mm.

Glumes lanceolate, 75-95% as long as the adjacent lemmas, glabrous and smooth or the midvein scabrous distally, midvein prominent, tips flat or almost flat, obtuse to acute or mucronate.

Lemmas usually glabrous, midvein prominent distally, often prolonged into an awn. Paleas from slightly shorter to slightly longer than the lemmas, slightly outwardly curved to the tip, tip flat, the intercostal region truncate or retuse. Lodicules unlobed, sometimes ciliate. Anthers 1.2-6 mm long.


Based on various references, there are about 30 taxa. Some of these may prove, on closer examination, to belong to other genomic genera. It is important to identify the infraspecific taxaon when reporting the genomic constitution because, in some instances, they have proven to be genomically different. For instance, Liu and Wang (1992) showed that Pseudoroegneria geniculata subsp. scythica contains both the E and St genomes which, using the taxonomy of this site, makes it a species of Thinopyrum. The name Pseudoroegnera geniculata refers to ALL the subspecies, not just Pseudoroegneria geniculata subsp. geniculata. Thus it cannot be said that Pseudoroegnerai geniculata, as currently treated, has only the St genome.

Examination of some specimens of Pseudoroegneria geniculata subsp. scythica indicates that it does have the morphological characteristics of that genus, but a more detailed study of the whole species.


Eurasia and western North America

Alternative interpretations

Pseudoroegneria is often included in Elymus or Elytrigia.

Type species

Pseudoroegneria strigosa(Nevski) A. Love

Known problems

There has never been a global treatment of Pseudoroegneria. Given the importance of its genome in the perennial Triticeae, this merits being given a high priority. Such a study should include an examination of morphological, cytological, genomic, molecular, and distributional characteristics of its members. It has been suggested, based on cytological evidence, that Pseudoroegneria spicata and Pseudoroegneria stipilifolia should be treated as a single species. The suggestion has not been followed by any of those working in the tribe.


Grasses of the Soviet Union Tsvelev, N.N. 1976. Zlaki CCCR. [Grasses of the Soviet Union]. Nauka, Leningrad [= St. Petersburg], Russia.

Flora Europaea Melderis, A. 1980. Elymus, p. 192-198 in T.G. Tutin, V.H. Heywood, N.A. Burges, D.M. Moore, D.H. Valentine, S.M. Walters, and D.A. Webb (Eds.), Flora Europaea, vol. 5. Cambridge University Press, Cambridge, England.

Flora of China, vol. 22 Pi, Jia and Shu Cao. 2006. Elymus, pp. 400-429 in Wu, ZY, P.H. Raven and DY Hong (eds). Flora of China, vol. 22. Science Press (Beijing) and Missouri Botanical Garden, St. Louis, Missouri, U.S.A.

Flora of North America, vol. 24. Barkworth, M.E., J.J.N. Campbell, and B. Salomon. 2007. Elymus, pp. 288-343 in M.E. Barkworth, K.M.C. Capels, S. Long. L.K. Anderton, and M. Piep (Eds), Flora of North America, vol. 24. Oxford University Press, New York, United States.