Species from genus Solidago are exceptionally successful worldwide invaders from North America [1]. Among about 120 Solidago species three are invaders, which so far have conquered Europe, large parts of Asia, Australia and New Zealand [2].In central Europe five representatives of the Solidago genus are found. Only one species (S. virgaurea L.) is native, while the other four are of American origin, namely: S. gigantea Aiton, S. canadensis L., S. altissima L. [S. canadensis var. scabra (Muhl.) Torr. and Gray] and S. graminifolia (L.) Elliot [3]. Three of the introduced taxa (S. gigantea, S. canadensis and S. altissima) are invasive and morphologically similar to each other. Their taxonomic status in Europe has been discussed [3][4][5][6][7][8]. The range of the fourth alien species, S. graminifolia, is small and limited to few locations in Europe [9,10].The basic chromosome number in Solidago species is x = 9. S. virgaurea and S. graminifolia are diploids (2n = 18). S. canadensis consists of diploid (2n = 18) and tetraploid plants (2n = 36), and S. altissima hexaploid (2n = 54), triploid (2n = 27) and tetraploid (2n = 36) plants of native origin [11,12]. While in Europe only diploid plants of these species are noted [7,13], in case of Solidago altissima the occurrence of additional Bchromosomes was observed [14,15]. Solidago gigantea occurs in three different cytotypes: diploid (2n = 18), tetraploid (2n = 36) and hexaploid (2n = 54), which represent the whole S. gigantea complex in native range and has also been found in Europe [16]. However, according to current data [17][18][19] in Europe only tetraploid populations of S. gigantea are known. Therefore, based on this variety in chromosome number, considerable morphological variety in these taxa could be expected [20]. It could also include differentiation in traits related to invasiveness as, e.g. stem height or inflorescence size [21].Several hypotheses focus on the reasons why alien invasive plants are more successful than other plants in occupying new areas [22][23][24][25]. There are numerous confirmations, that plants in the new range could differ from their ancestors, including
AbstractInvasive plants in their new range can differ from their ancestors, including traits ultimately influencing habitat preferences, competitiveness and dispersal ability. In Europe Solidago species are considered as one of the worst invaders of American origin. In this study the frequency of occurrence of Solidago species, their soil preferences and morphological diversity, in Silesia (southwestern Poland, Central Europe) were surveyed. On the basis of phytosociological relevés, made using the Braun-Blanquet method, in 75 plots, we determined the composition of species co-occurring with particular Solidago species. The height of ramets, as well as length and width of inflorescences of Solidago species were measured. We also determined the basic soil properties and noted the presence of trees overshading the ground vegetation. The compositional variation of vegetation and its r...