Rare plants of rock complexes in the Middle Vltava Region (Central Bohemia)

Hardly accessible bottom parts of 15 rock complexes in the area of Slapy and Kamýk water reservoirs were studied by using an infl  atable dinghy. In total, we recorded 74 red-listed species of vascular plants. One species is regarded critically endangered (Asplenium ceterach), three endangered (Potentilla lindackeri, Pulsatilla pratensis, Silene nemoralis) and 32 vulnerable (e.g. Achillea pannonica, Aster amellus, Carex curvata, Carlina biebersteinii, Dictamnus albus, Pilosella auriculoides, P. rothiana, Rosa marginata, Trifolium rubens, Vicia pisiformis). New natural localities were found for Campanula gentilis, Sesleria caerulea and Sorbus danubialis in more southern parts of the valley of the Vltava River than hitherto known. A map with the southernmost localities of additional species in the area is provided. Also several rare plants were recorded also in littoral communities. The species richness and composition are mainly influenced by the geological bedrock, size of rocky outcrops, geographical position and habitat diversity. Localities with the highest numbers of rare species are characterized by the presence of basic volcanic rocks or a large geological diversity. In the southern part of the study area, granodiorite rocks with a lower species richness of rare plants dominate at sites.