| Hystrix Moench is a small perennial genus of the tribe Triticeae (Poaceae). It was established by Moench (1794) according to the distinct morphological character of lacking glumes, or long setaceous awn-shaped ones, if present. The type species is Hystrix patula Moench. Since then, about eleven species have been included in Hystrix (Hitchcock 1951, Bor 1960, Tzvelev 1976, Kuo 1987, Osada 1993). The genus Hystrix revised by Baden et al. (1997) includes six species: H. patula, H. californica, H. duthiei, H. komarovii, H. coreana and H. sibirica. H. duthiei comprises three subspecies, H. duthiei ssp. duthiei, H. duthiei ssp. longearistata and H. duthiei ssp. japonica. All of them are tetraploids (2n=4x=28) except H. californica, which is an octaploid (2n=8x=56). The natural distribution of Hystrix is disjunct with two species in North America (H. patula and H. californica), and the remaining in Central and Eastern Asia (Dewey 1982, Love 1984). Cytologically, Church (1967) reported that H. patula had a close affinity to species of the Elymus canadensis complex and treated H. patula as E. hystrix L. Species of E. canadensis complex contain the same basic genome formula, StH (Dewey 1982). Jensen & Wang (1997) reported that H. coreana and H. californica had the same genome constitutions NsXm as Leymus Hochst., and combined H. coreana into Leymus. Therefore, the definition of Hystrix and its precise taxonomic status are still under discussion today. Some authors included the species in either Hystrix (Sakamoto 1973, Kuo 1987, Osada 1993, Baden et al. 1997, Zhou et al. 2000)...
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