A complete list of all alien taxa ever recorded in the flora of the Czech Republic is presented as an update of the original checklist published in 2002. Alien flora of the Czech Republic consists of 1454 taxa listed with information on their ecology and biogeography.
The Czech alien flora consists of 350 (24.1%) archaeophytes and 1104 (75.9%) neophytes. There are 44 taxa on the list reported in the present study for the first time as aliens introduced to the Czech Republic or escaped from cultivation.
Of the total number of taxa, 985 are classified as casuals, 408 as naturalized but not invasive, and 61 as invasive. Alien taxa contribute 29.7-33.1% to the total country's plant diversity; taking into account only naturalized taxa, a permanent element of the country's flora, the figure is 14.4-17.5%.
Analysis of the dates of the first record indicates that alien taxa in the flora have been increasing at a steady pace without any distinct deceleration trend.