Bromus (Poaceae) in Central Europe. Synopsis and identification scheme

Abstract

The taxonomy and (to minor extent) the distribution of 25 species and subspecies of the genus Bromus in Central Europe, Germany and Austria, is surveyed and commented. Centred in the northwestern Old World, all the taxa of the genus Bromus evolved on man-made disturbed habitats up to present and, therefore, are anecophytes, so-called “homeless plants” without any stands in natural vegetation. In the considered region they are either indigenous (B. arvensis, B. commu­tatus, B. grossus, B. hordeaceus with some subspecies, B. incisus, B. lepidus, B. pseudosecalinus, B. racemosus, B. secalinus, and now extinct (B. brachystachys, B. oostachys), or non-indigenous, invaded from abroad but well established (casuals omitted). Attention is paid to the mode of origin of the polyploid and prevalently autogamous taxa, in some cases with special references to recently published molecular data. The hypothesis is formulated, that the tetraploid B. hordeaceus (2n = 4× = 28) is an autotetraploid resulted without hybridization from doubling and subsequently changing a diploid genome, not as in true allotetraploids from a combination of two sets of distinct genomes. Taxa new to science are B. pseudosecalinus subsp. fallacinus, the nothospecies B. ×robustus and the combination B. hordeaceus subsp. mediterraneus. Neotypes of B. ×hannoveranus and B. secalinus subsp. billotii are designated. – For a quick determination of Bromus species a tabular (lateral) key is elaborated.