Seeds of Lactuca sativa L. (model plant) and Quillaja saponaria Mol. (native tree) were subjected to germination
in direct contact with leaves, pods and seeds from invasive Acacia dealbata Link. (Fabaceae) to
reveal whether morphological changes occur at radicle level. Bioassays were carried out with plant material
deposited underneath A. dealbata´ıs canopy under natural conditions at Mediterranean ecosystem in
South America. Segments of radicle tip, cell elongation zone and root hair zone were analyzed under scanning
electron microscopy. The three plant parts from A. dealbata inhibited the formation of root hairs and
altered the rhizodermis (deformation and tissue destruction) of the two recipient species. In the case of
Q. saponaria, an increase in thickness in the cell elongation zone was observed and internal tissues up to
the vascular cylinder in the root hair zone were intensely damaged. The root cap and meristematic region
suffered structural changes and damage resulting from the contact with leaves and pods. All morphological
effects have been attributed to the impact caused at root level by potential allelochemicals released
by different tested plant materials of A. dealbata. These results suggest that the morphological changes
and damage produced by A. dealbata at the radicle level may pose a threat to the growth and survival of
the recipient species.