Additions to the flora of the Czech Republic. XI.

This eleventh part of floristic contributions includes newly published data of critically endangered species and data unpublished so far. Data of alien species found in the Czech Republic for the first time (Calystegia hederacea, Corispermum gmelinii, Miscanthus sacchariflorus, Scolymus maculatus) are sum­marized. The species Rubus silvae-bohemicae described from the Czech Republic as new to science and Rubus lucentifolius a species new to the Czech Republic, are also listed below. Furthermore, critically endangered species (according to the Red List of Vascular Plants of the Czech Republic) are reported from new sites (e.g., Atriplex rosea, Botrychium multifidum, Carex obtusata, Centunculus minimus, Chenopodium murale, Chimaphila umbellata, Cyperus michelianus, Euphrasia slovaca, Gentianella praecox subsp. bohemica, Heleochloa schoenoides, Hypochaeris glabra, Juncus capitatus, J. gerardii, J. sphae­rocarpus, Lindernia procumbens, Laris loeseliiip, Littorella uniflora, Lycopodiella inundata, Moneses uniflora, Montia fontana, Ophrys insectifera, Orchis ustulata, Orobanche elatior, O. coerulescens, Polycne­mum majus, Potamogeton coloratus, P. gramineus, Pulicaria dysenterica, Pyrola chlorantha, Radiola linoides, Ribes petraeum, Senecio doria, Spiranthes spiralis, Thesium dollineri, Trapa natans, Urtica kioviensis, Veronica opaca, V. scardica, Xeranthemum annuum). Finally, less rare and threatened species are reported from areas where they had not been recorded yet (e.g. Cruciata pedemontana, Polygala serpyllifolia, Spergularia echinosperma).