Artificial plants and even a sturdy branch would be appreciated by your bp, especially if it's in a glass tank. I wouldn't suggest a real plant though, unless you've done your research about how it may affect your snake (is it toxic to them etc.) and it's in a pot. Planting in the substrate wouldn't be wise, it would make cleaning difficult and the excess dampness on his substrate from watering could lead to all sorts of nasty things like bacteria, mold and scale rot.
I don't mind living in a man's world as long as I can be a woman in it.
I agree. Fake vines, plants and branches can provide clutter to fill in some of the dead space, and also provide additional places to hide and/or bask...