Hedera helix

Is the ivy on the wall or the wall on the ivy?

The species Hedera helix, commonly known as ivy, belongs to the Araliaceae family and is the only native species of the family in Greece. Hedera helix climbs relatively smooth vertical surfaces, such as a wall, by means of a complex method of attachment. As the roots come into contact with the surface, they extend their tiny hairs into whatever small cracks are available and secrete glue-like nanoparticles. After some time, the Hedera helix becomes one with the surface it is attached to. Removing the ivy will be fatal to both the wall and its host.