The facade of this building has been retained in James Watt Street in Glasgow while all around the newbuild carries on at some pace. It is pleasing that some of the older architecture is retained, although how successful this will be when the newbuild is tagged on behind is anyone's guess. And don't you just love how there is always a bush or tree growing from these buildings?
The tree branch is a tradition - for good luck and to give thanks to the trees that made the building. In Florida they use palm trees (no comment). I have not idea where the tradition originates, but I know that the Amish nail a fresh bough on new barns, and have for many a generation. I suspect that it goes back quite a ways...
Actually in the UK, it tends to be buddleia growing out the side and tops of buildings. It's a true "survivor" plant. There's one growing on top of the building next to my home, as is another one growing out of the side of the local branch of Snappy Snaps. It's not on purpose... just nature taking over as moss does.