P. spinosa L. is a common shrub in old hedges and forest edges in Flanders, especially on richer soil types. According to recent botanical inventories for woody plants in Flanders, many locations are described where autochthonous P. spinosa grows together with intermediate forms between blackthorn and blue berried damson and, in rare locations with blue berried damson (P. domestica subsp. insititia (L.) Bonnier & Layens) itself. By means of natural hybridisation and introgression between wild and cultivated taxa, new combinations of features can arise that result in populations with new characters. Those populations can contain potential for further anthropogenic selection.

The evaluation of the biodiversity and the extent of differentiation between the populations studied have repercussions on concrete conservation strategies. This project will thoroughly characterize blackthorn (P. spinosa), damson (P. domestica subsp. insititia) and their morphological intermediate forms (P. x fruticans Weihe). The affinity with cherry plum (P. cerasifera Ehrh.), regional cultivated plum varieties and archaeological findings. These objectives can be achieved by use of molecular marker techniques, linked with a thorough morphological analysis.

Beside the use of evolutionary neutral markers (AFLP, Microsatellites) that are applied routinely in population genetic studies, also S-allele diversity analysis will be carried out. Furthermore cpDNA diversity will be studied to gain an insight into the population structure of the different taxa. Because most taxa studied are polyploid, determinations of the degree of ploidy are carried out by means of flow cytometry to situate the hybrid taxa.