An ex-situ collection of serpentine plants was made in the Botanical Garden at the Bulgarian Academy of Sciences in Sofia. Fifty-three taxa of higher plants of the Bulgarian serpentine flora, collected  from the Eastern Rhodopi Mts, are grown on a rocky place of 25 m² and 2 m in height. The total number of individuals collected for transplantation is 103, belonging to 26 plant families distributed in the following categories: 1) endemics narrowly restricted to serpentine; 2) local indicator species showing high fidel­ity but not restricted to serpentine; 3) wide-ranging species that occur in a variety of habitats underlain by both normal (zonal) and ultrabasic soils, 4) medicinal plants.

The plants growing on serpentine soils accumulate heavy metals in different levels. The group of the hyperaccumulators  as well as some medicinal plants were of special interest. The objectives of the study were to widen understanding of the distribution of the nickel hyperaccumulators and their uptake behaviour in relation to the characteristics of their soil environments.  Collection and chemical analysis of both plant and soil samples has allowed evaluation of phenotypic efficacy in hyperaccumulating nickel. In total, 10 taxa were studied.

The Ni-content  in plants growing ex-situ  were lower  which can be result of the changed ecological conditions. The highest Ni concentrations in leaves were found in Alyssum murale and  Thlaspi kovatsii in ex-situ collection. Medicinal plants do not show hyperaccumulation of Ni both in ex-situ and in-situ. Also Ni-content in their leaves in ex-situ collected material was quite lower. This result give reason to consider  medicinal plants growing on serpentines suitable for pharmaceutical uses after ex-situ cultivation.

Key words:, serpentine, medicinal plants,  Ni-hyperaccumulators, ex-situ