Flora and phytogeography of the Czech Republic.

A review of the flora and phytogeography of the Czech Republic is given. The diversity of plants in this country reflects its geographic position in the centre of Europe, local natural conditions and the effect of intense human activity on the landscape. The Czech flora includes 148 families, 916 genera, 3557 species (plus 194 additional subspecies) and 609 hybrid vascular plants. Families richest in species are Asteraceae (662 species), Rosaceae (316), Poaceae (275), Fabaceae (170), Brassicaceae (148), Cyperaceae (127), Lamiaceae (112), Caryophyllaceae (108) and Apiaceae (100). Most of these species are native and 36.0% are alien. The spectrum of life-forms is dominated by hemicryptophytes (45.7%), followed by therophytes (22.3%), phanerophytes (14.4%), geophytes (9.3%), chamaephytes (5.1%) and hydrophytes (3.2%), while the percentage of epiphytes is negligible (only two species). Several species that occur in the Czech Republic are relicts from glacial and early postglacial periods. Examples of arctic, boreal, alpine, steppe and other sorts of relicts are listed. Because of the relatively small size of this country and the considerable climatic and vegetational changes caused by glaciations, which repeatedly eliminated the local flora, endemism is relatively low in the Czech Republic. All endemics are of Quaternary age (neoendemics). A revised list of endemic species and subspecies includes 74 taxa endemic to the Czech Republic and adjacent border regions, which is 2% of the total vascular plant diversity. Of these, 48 taxa are strictly Czech endemics (defined by the borders of the country), the distributions of the other 26 taxa extend slightly beyond the borders of this country (mostly by less than 1 km) in the summit areas of the Krkonoše/Karkonosze Mts and/or in the Králický Sněžník/Śnieżnik Kłódzki Mts. Hieracium and Sorbus are the genera with the greatest number of endemics (25 and 11 species and subspecies, respectively). Patterns in the distribution and occurrence of endemics in different types of habitat are discussed. The greatest concentration of endemics is in the Krkonoše Mts, where they occur mostly in subalpine habitats, such as natural grasslands above the timberline, summit rocks and rocky slopes, and various sites in glacial cirques including avalanche tracks. Other endemics of subalpine habitats occur in the Králický Sněžník Mts and Hrubý Jeseník Mts. Endemics at low altitudes mostly occur on rocky outcrops and in associated open thermophilous forests and grasslands, less frequently on open sandy areas, in fens and various types of forest. Maps of the distribution of endemics in the Czech Republic are presented. The majority of Czech endemics are rare and/or strongly endangered and included on the Red List of the Czech flora, and seven are extinct or missing. Changes in understanding of Czech endemics are reviewed and evolution of endemics discussed. The Czech Republic is situated at the intersection of several important European migration routes. The Czech flora is composed of almost all the floristic elements that occur in central Europe of which the Central-European geoelement is dominant. Other well represented geoelements include the Central-European-(sub-)alpine, Arctic-alpine, Boreal, Sub-boreal, Sub-Atlantic, Sub-Mediterranean, Pontic, Sub-pontic and South-Siberian. Examples of all geoelements are listed. The limits of the distributions of a number of widespread species are in the Czech Republic. These species are distinguished as boundary or outlying elements. Examples of species that in the Czech Republic are at the limits of their distributions, which range in different directions, are listed. Groups of species with similar ecogeographic features within the Czech Republic are distinguished as regional types of distribution (phytochorotypes). 15 basic phytochorotypes are listed, defined and illustrated using maps. Phytogeographical division of the Czech Republic is described. Three principal phytogeographical regions are recognized within the country, which are based on the dominant flora and vegetation that reflects specific regional topography and climatic conditions. These regions are further subdivided into phytogeographical provinces, districts and subdistricts. All of these phytogeographical units (phytochoria) are listed and their position illustrated on a map.