Cyperus eragrostis – a new alien species for the Czech flora and history of its invasion of Europe.

Cyperus eragrostis Lam. was first recorded in the Czech Republic in an empty water reservoir at Jablonec nad Nisou (N Bohemia) in 1999. In this study, herbarium specimens of C. eragrostis in large herbaria in the Czech Republic were revised and the invasion of Europe by this species was reviewed. A brief description of C. eragrostis is given, distribution map of the temporal course of its invasion is presented and the species’ ecology in Europe characterized. Accompanying vegetation and results of the analyses of soil from the site are described. How the plant reached this locality remains unknown. The occurrence was only ephemeral as the only tussock was destroyed when the water reservoir was refilled.