Abstract
The twelfth part of the series on the distributions of vascular plants in the Czech Republic includes grid maps of 105 taxa in the genera Androsace, Anthemis, Aristolochia, Berteroa, Celtis, Cnidium, Cynodon, Descurainia, Echium, Erechtites, Euphorbia, Homogyne, Laserpitium, Linaria, Pinus, Rosa, Sesleria, Spiraea and Verbena. These maps were produced by taxonomic experts based on examined herbarium specimens, literature and field records.
Both native and alien species are represented. In addition to widespread plants such as Berteroa incana, Descurainia sophia, Echium vulgare, Euphorbia cyparissias, Linaria vulgaris and Pinus sylvestris, plants that are rare or have more localized distributions were also studied, with 39 of them being on the national Red List.
The highest rates of decline, smallest population sizes and the highest degree of population fragmentation are found in critically threatened spe-cies, represented by Androsace septentrionalis, Echium maculatum, Euphorbia salicifolia, Laserpitium archangelica and Sesleria uliginosa. Two species, Androsace maxima and Linaria arvensis, have been extirpated from this country; however, the former survives in a university botanical garden where it has become naturalized.
With 13 archaeophytes and 41 neophytes among the mapped taxa, over a half of them are alien to the Czech Republic. Two of the alien species have become invasive.
Pinus strobus has considerable physical impact on ecosystems particularly in sandstone landscapes, while Erechtites hieraciifolius started to be common mainly in forest clearings, with this spread being facilitated by the increasing extent of this habitat in the landscape due to the recent bark beetle outbreak. Another species that regionally started to spread intensively during recent decades is Cynodon dactylon.
Five species were identified as new neophytes for the Czech Republic. Of these, Aristolochia macrophylla and Pinus contorta escaped from cultivation, Euphorbia nutans and Verbena incompta were unintentionally imported with various commodities, whereas Linaria dalmatica was introduced through the combination of intentional sowing and spontaneous escape from cultivation.
Important revi-sions and adjustments are provided for taxonomically difficult and species-rich genera such as Euphorbia, Pinus, Rosa, Spiraea and Verbena. Spatial distributions and often also temporal dynamics of individual taxa are shown in maps and documented by records included in the Pladias database and available in the Supplementary materials.
The maps are accompanied by comments that include additional information on the distribution, habitats, taxonomy and biol-ogy of the taxa.