Distribution of four Atriplex species with different degrees of invasiveness in the Czech Republic.
The distribution of four alien Atriplex species (A. sagittata, A. hortensis, A. tatarica and A. rosea) with different degrees of invasiveness in the area of the Czech Republic was compared. The species can be divided into two groups which are morphologically very similar but with strictly different ecological behaviour. A. sagittata and A. hortensis belong to the first group, which represents the primitive oraches within the genus Atriplex. Whereas A. sagittata is the most invasive representative of the genus in the Czech Republic, A. hortensis is the species with limited distribution strongly dependent on relatively common cultivation and subsequent escape from cultivation. The second group contains A. tatarica and A. rosea which are phylogenetically derived species within the genus Atriplex. A. tatarica is a common species distributed mainly in the warmer areas of the Czech Republic with a tendency to spread further. On the other hand, A. rosea is a species which was relatively common in the past, but today survives in a few localities mainly in the warmest areas. The distributions of all these species in the area of the Czech Republic were based on herbaria, floristic data and own field investigations. The main focus was on comparison of number of localities, distribution areas, altitudal ranges and habitat differentiation. The limitations in the distribution of particular species is discussed in relation to the species ecology.