At present there are 1454 alien taxa (species, subspecies, varieties, hybrids and cultivars) of vascular plants recorded in the Czech Republic, among them 350 archaeophytes, introduced since the beginning of the Neolithic until the end of the Middle Ages, and 1104 neophytes, introduced in the Modern Period. Of the total number, 985 (67.7%) taxa are classified as casual, 408 (28.1%) as naturalized but non-invasive and 61 (4.2%) as invasive. Aliens make up 33.1% of the total plant diversity recorded in this country, or 14.4% of the permanently present flora. The highest levels of invasion of plant communities are recorded in cities and villages and their surroundings, floodplains of large rivers, disturbed landscapes in the north, and agricultural landscapes and forest plantations in the warm lowlands, especially in southern, central and eastern Bohemia. The habitats and vegetation types harbouring the highest percentages of alien species in the Czech Republic are generally those with a high level of disturbance or with a fluctuating input of nutrients.
REPUBLIKY, F. (2012). Flora and Vegetation of the Czech Republic. Ibot.Cas.Cz, 505–573. Retrieved from http://www.ibot.cas.cz/preslia/P123Editorial.pdf