Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

Black cherry (Prunus serotina Ehrh.) belongs to quite common and the best known invasive woody plants of alien origin occurring in central Europe. On the other hand, little is known about the degree of settling of another North American representative of the Prunus genus from the Padus subgenus – the chokecherry (P. virginiana L.). A considerable morphological similarity of the above-mentioned taxon to P. padus L. is a cause of fairly significant problems associated with its identification. It is not easy to distinguish these related indigenous species, common in forests, as well as in mesophilous thickets in the area of entire Europe. That is why P. virginiana is usually unnoticed and, consequently, it is overlooked in floristic studies. On the basis of the data derived from a variety of sources, mostly collected by the authors in the course of their field trips, supplemented with information from literature, as well as unpublished notes obtained from different persons, information concerning the distribution of secondary P. virginiana sites in Poland is summed up. The article presents a list of 28 such sites together with a map on which their locations have been marked. The discussed species was observed most frequently in the forest environment on eutrophic as well as mesotrophic broad-leaved forest sites in shrub thicket areas at the edge of dense forests. It was also found in broad-leaved and pine coniferous forest underbrush as well as in mid-field thickets. It was established that in Poland, it was not only fully settled in on semi-natural sites but it also encroached upon forest phytocoenoses of natural character. In order to draw attention to possibilities of P. virginiana occurrence in other, hitherto unrecognised synanthropic sites, some remarks and observations concerning morphological features and phenological properties of this taxon in field conditions were included.