And they mean that literally. I just learned about the Rose of Hildesheim. A Rosa canina, or wild dog rose, it is thought to be about 700 years old. Among the many feats of its long life, it was bombed during WWII. Not that the rose was a target, I’m sure, but the cathedral, which gave it support, was. All the above-ground shrub was believed to have been destroyed but the roots were intact. The stone rubble created something of a haven for the rose while the half-timbered houses around it burned.
I read something about a thousand year rose and then did a web search. There’s a good wikipedia page with links to other references.