XVI International Botanical Congess

Morphology and molecular variation from RAPDs were investigated in the polyploid Salix alba - S. fragilis hybrid complex through a screening of full-sib progenies of interspecific crosses. On basis of genetic similarities and ordinations, a reference system for identification of clones was established using presumed pure species and introgressants. The reference system was checked against European putative pure species to ensure reliability beyond a regional scale and was used to elucidate patterns of hybridization on a local scale in the hybrid willow complex from tidal mudflats of the river Schelde in Belgium. RAPDs suggested that both species have kept their gene pools well separated and that hybridization actually does not seem to be a dominating process leading to an excess of hybrid individuals in riparian habitats.