ABSTRACT
Despite intensive recent research, the taxonomic position of individual species has not been fully resolved, which makes the identity of some historical records unclear due to historically poor accessibility of regions within the native range, isolated research in Russia, and possible hybridization among hogweed species. Heracleum mantegazzianum is native to the western part of Greater Caucasus (Georgia, Russia), while the other two closely related invasive tall hogweeds came to Europe from Iran, Iraq and Turkey (Heracleum persicum, invasive in northern Europe in Scandinavia), and from the central part of Greater Caucasus (Heracleum sosnowskyi, now occurring in some of the former Soviet republics, for example Ukraine, and also reported from Hungary). All three species were introduced to Europe as garden ornamentals in the 19th century. Two of them (H. mantegazzianum and H. sosnowskyi) were also grown in some regions of Central and Eastern Europe as pasture crops; this practice resulted in large areas of abandoned fields being infested with hogweeds in the former USSR (for example Ukraine, Latvia) (Buttenschon and Nielsen, 2007; Jahodová et al, 2007a). These attempts, however, failed because the plants pose a high risk to human health due to their phototoxic sap, which is also dangerous to animals, and in the case of H. sosnowskyi due to the fact that its anise smell tainted dairy products.
