StY or StStY, the St genome coming from Pseudoroegneria. There are no monogenomic species that have only the Y genome. It has been suggested that it may be derived from the St genome, being modified in such a way that its chromosomes no longer pair with those of the St genome. This is still only a suggestion.
There is evidence of cytological and geographic differentiation within Roegneria
Plants perennial with solitary spikelets. Paleas curving to the rather broad, flat, tip (025-1.5 mm wide).
Plants perennial, usually not rhizomatous, not stoloniferous. Culms 20-150 cm tall, lowest internode 0.8-4.4 mm thick.
Leaves 05.5-10 mm wide, flat, involute, or convolute, sometimes convolute only at the edges.
Inflorescence spikelike, erect, nodding, or drooping; rachis tough, terminating in a spikelet, cross section varied, lowest internode from subequal to more than 2.5 times the length of the middle internodes; middle internodes 3-16 mm long; disarticulation below the florets.
Spikelets solitary, tangential to the rachis, pedicels 0.2-0.8 mm, lowest spikelet usually longer than the adjacent internode, sometimes slightly shorter, middle spikelets usually 3 times longer than the adjacent internode.
Glumes 3-16 mm long, sometimes shorter than the adjacent lemmas, sometimes equaling the distal lemma, lanceolate to lance-ovate, membranous, glabrous to densely hairy, hairs stiff to flexuous, sometimes scabrous, often scabrous only over the veins, veins 3-8, tip acute, mucronate, or awned, awns straight, to 7 mm long.
Lemmas varying from smooth and glabrous to scabrous over the veins or their whole surface to hairy over all or part of their surface, usually rounded over the midvein or keeled distally, tips often bidentate, acute, mucronate, or the midvein extending into a straight to reflexed awn up to 45 mm long. Paleas not winged, somewhat rounded to the rather flat tip, tip 0.25-1.5 mm wide. Lodicules lobed, ciliate distally. Anthers 1-3 mm long.
There are approximately 90 species of Roegneria.
Eurasia, with its greatest concentration being somewhat to the south of that of Elymus.
Roegneria is often included in Elymus (see, for example, the Grasses of the Soviet Union, Flora Europaea, Flora of China, and Flora of North America). It is recognized here because it is genomically distinct, seems to be morphologically distinguishable, and has a rather different distribution from other genomic groups.
Roegneria caucasica K. Koch
The description provided here is based on examination of relatively few species and relatively few specimens plus consideration of information in the Flora of China. As the sampling is expanded, it is to be expected that parts of the description will need to be modified.
There are still many species that have not been examined in terms of their genomic constitution. Once it is possible to use molecular markers to detect all the different genomes present in the perennial Triticeae, it will be easier to determine whether the paleal characters cited are a reliable means for distinguishing the StY and StStY species from other genomic groups.
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.