Distributions of vascular plants in the Czech Republic. Part 2

The second part of the publication series on the distributions of vascular plants in the Czech Republic includes grid maps of 87 taxa of the genera Antennaria, Aposeris, Astragalus, Avenula, Bidens, Carex, Cenchrus, Centunculus, Convallaria, Crocus, Cryptogramma, Cyperus, Dryopteris, Gladiolus, Gratiola, Helictochloa, Hierochloe, Lindernia, Maianthemum, Myriophyllurn, Notholaena, Nymphoides, Radiola, Schoenoplectus, Sisyrinchium, Spergularia, Tillaea, Veratrum and Veronica. The maps were produced by taxonomic experts based on all available herbarium, literature and field records. The plants studied include 56 taxa registered in the Red List of vascular plants of the Czech Republic, some of which showed remarkable declines. Astragalus arenarius, Hierochloe odorata and H. repens, as representatives of vegetation of inland sand dunes, are critically threatened due to conversion of their habitats to arable land, local sand mining, afforestation, changes in landscape management and eutrophication followed by succession. Each of them survives at a few localities and their populations are poor. Competitively weak wetland annuals, confined to open habitats such as exposed fishpond littorals and river beds, abandoned sand-pits and wet arable fields, have considerably declined and disappeared from large areas as a result of agriculture and fish-farming intensification, in particular fertilization and restriction of summer drainage of fishponds, and other changes in land-use. These include Centunculus minimus, Cyperus flavescens, C. michelianus, Lindernia procumbens, Radiola linoides and Tillaea aquatica. Observed recently at a few sites only, they are all classified as critically threatened. A map is for the first time provided also for Spergularia kurkae, a newly recognized species and a central European endemic. Astragalus asper, Schoenoplectus supinus and Veronica pumila are now extirpated from the country's flora. In contrast, Spergularia marina, until recently confined to natural saline habitats and very rare, has been spreading along roads that are treated by de-icing salts. Examination of an old herbarium voucher showed that the only record of Astragalus alo-pecuroides in the Czech flora actually refers to the species whose correct name is A. alopecurus. Further introduced casuals mapped in this paper include Bidens pilosus, Cenchrus echinatus, Gratiola neglecta and Lindernia dubia, each introduced to only a few sites. Bidens connatus was recorded at two dozen sites and appears to have spread as a consequence of the great floods in 2002. Typical examples of naturalized neophytes are Veronica filiformis and V. peregrina, both currently known from many parts of the country. Invasive aliens are represented by Bidens frondosus, which began to spread in the 1930s and now is frequent throughout the country. Spatial and temporal dynamics of individual species are shown in maps and documented by records included in the Pladias database and available in Electronic appendices. The maps are accompanied by comments, which include additional information on distribution, habitats, taxonomy and biology of the species.