Influence of serpentine soils on the flavonoid content of Hypericum populations growing in Bulgaria

The effect of environmental factors on the production of secondary metabolites by plants has attracted a considerable amount of attention. Most species populations growing on serpentine soils are adapted to these special edaphic conditions in different ways. In this study we investigated the flavonoid content in Bulgarian Hypericum populations from five Hypericumspecies (H. cerastoides, H. aucheri, H. montbretii, H. perforatum and H. olympicum) to evaluate the differences between plants growing on and off serpentine. The results showed that the serpentine substrate influences the amount of flavonoids in Hypericum species.   Key words: Hypericum, flavonoids, serpentine.