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Genomic constitution

Hystrix, when it is recognized, includes perennial Triticeae that do not have glumes or have very reduced glumes. The problem is that it appears that reduction of the glumes appears to have occurred in several different groups, notably Elymus, Leymus, and Stenostachys. The type species, Elymus hystrix [= Hystrix patula] is an StH species.

If, as here, the type species of Hystrix is included with other StH species in Elymus, it becomes necessary to determine where the other species should be placed. Current evidence suggests that some of the remaining species belong in Elymus but others are better placed in Leymus. Zhang (2009) found Hystrix komarovii had the N genome of Psathyrostachys but that the other one seemed to be most closely related to the E genome of Thinopyrum. One North American species has already been transferred to Leymus. The other species are native to China and Japan. Hystrix is recognized in the Flora of China and the treatment of Japanese Triticeae but Yen & Yang () include most of its species in Leymus.

Distinguishing features

Hystrix, when it is recognized, includes perennial Triticeae that do not have glumes or have very reduced glumes. The problem is that it appears that reduction of the glumes appears to have occurred in several different groups, notably Elymus, Leymus, and Stenostachys. The type species, Elymus hystrix [= Hystrix patula] is an StH species.

Description

Plants perennial. Glumes absent.

See Alternative interpretations.

Size

If recognized, the genus includes about 6 species, four in China and Japan and two in North America.

If, as here, the type species of Hystrix is included with other StH species in Elymus, it becomes necessary to determine where the other species should be placed. Current evidence suggests that some of the remaining species belong in Elymus but others are better placed in Leymus. One North American species has already been transferred to Leymus. The other species are native to China and Japan. Hystrix is recognized in the Flora of China and the treatment of Japanese Triticeae.

Distribution

If recognized, the genus is native to China, Japan, and North America.

If, as here, the type species of Hystrix is included with other StH species in Elymus, it becomes necessary to determine where the other species should be placed. Current evidence suggests that some of the remaining species belong in Elymus but others are better placed in Leymus. One North American species has already been transferred to Leymus. The other species are native to China and Japan. Hystrix is recognized in the Flora of China and the treatment of Japanese Triticeae.

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Alternative interpretations

The type species belongs in Elymus; the placement of the other species is somewhat problematic. If, as here, the type species of Hystrix is included with other StH species in Elymus, it becomes necessary to determine where the other species should be placed. Current evidence suggests that some of the remaining species belong in Elymus but others are better placed in Leymus. Zhang (2009) found Hystrix komarovii had the N genome of Psathyrostachys but that the other one seemed to be most closely related to the E genome of Thinopyrum. One North American species has already been transferred to Leymus. The other species are native to China and Japan. Hystrix is recognized in the Flora of China and the treatment of Japanese Triticeae but Yen & Yang () include most of its species in Leymus.

Type species

Hystrix patula Moench = Elymus hystrix L.

Known problems

If, as here, the type species of Hystrix is included with other StH species in Elymus, it becomes necessary to determine where the other species should be placed. Current evidence suggests that some of the remaining species belong in Elymus but others are better placed in Leymus. One North American species has already been transferred to Leymus. The other species are native to China and Japan. Hystrix is recognized in the Flora of China and the treatment of Japanese Triticeae.  Zhang (2009) found Hystrix komarovii had the N genome of Psathyrostachys but that the other one seemed to be most closely related to the E genome of Thinopyrum. One North American species has already been transferred to Leymus. The other species are native to China and Japan. Hystrix is recognized in the Flora of China and the treatment of Japanese Triticeae but Yen & Yang () include most of its species in Leymus.

References

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.