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We have classified 11 species recently recognized as belonging to the genus Elymus into a resurrected and legitimate genus Campeiostachys Drobov according to the International Code of Botanical Nomenclature. Our action is based on the rationale of monophyly, discrimination, and practicality discussed in detail. Currently Elymus contains a vast number of species with different genomes which often, but not always, can be differentiated by cytological and molecular features, but are difficult to separate by traditional morphology, although an effort to do so is detailed and discussed. This difficulty can be attributed to the dominance effect of a particular genome on the other genome(s) present. Campeiostachys, with genome constitution StStHHYY, is a recent addition to a number of genera recently segregated out of Elymus, i.e. Douglasdeweya (StStPP), Kengyilia (StStPPYY), and Roegneria (StStYY, StStStStYY). A key to Campeiostachys taxa is provided, along with taxa descriptions, distribution, nomenclature, and cytology. Nineteen nomenclatural novelties, or combinations, resulted from this work, 10 species names, and nine varietal names.

We document diagnostic characteristics of Roegneria by which it differs from genera with which it has often been confused. Characteristics of Roegneria are the absence of underground runners; slightly curved and elongated rachis with long internodes, each rachis node bearing one spikelet only and often adhering to the internode, and inflorescence appearing more or less one sided because of the disposition of the spikelets; spikelet functionally disarticulating below the glumes; glume symmetric with nerves tapering in the apex; lemma with nerves tapering in the apex; and palea generally shorter than the lemma, and if equal to the lemma then the tip obtuse, truncate, or retuse. Genera difficult to separate from Roegneria are Agropyron, Elymus, and Elytrigia; these share one or more characteristics but none have them in the same combination. We also stress the merit of recognizing Roegneria for germ-plasm utilization. Key words: Roegneria, Triticeae, generic limits, Elymus, Agropyron, Elytrigia.

Psathyrostachys huashanica Keng is a native Triticeae species in central China. In order to study its biosystematic relationships with Roegneria ciliaris (Trin.) Nevski, another native Triticeae species in China, we observed the meiosis of their F1 hybrid and found variations in both chromosome number per cell and cell size. The diminution of chromosome number by means of chromosome elimination is well known in wide hybrids. However, increase in number of chromosome of the pollen mother cells (PMCs) is uncommon. This phenomenon accom panied with multipolar division is similar to that in Iris japonica Thunb., a spontaneous plant widely distributed in Far East (Sinoto 1921, Yasui 1939). Cytomixis was described by Gate (1908) in Oenothera and then observed in many species and hybrids (a review see Whelan 1974). We supspected that cytomixis might also have occured in early stages of microsporogenesis in this hybrid. Thus, an extensive study on the microsporogenesis of this F, hybrid became necessary. This paper reports the F, hybrid of P. huashanica with R. ciliaris and describes the obser vation of conjugation tube, conjugation opening, coenocytism, chromosome number dim inution and multiplication, non-synchronous division, multipolar division and cytomixis in this F, hybrid. The significance of these processes in evolution is also discussed.