If you like the scent of lemon, then this is the plant for you. It's called Aloysia triphylla, or more commonly the lemon scented verbena, and does this have a scent!
If you merely brush past it, the smell fills the air, hence the reason I have it right at the back door, so as residence and guests come and go, everyone in the vicinity benefits!
Of course the plant is not amazing to look at, but who cares, a touch of colour with the fragrance is enough.
You can do plenty more with it, such as make tea, use leaves in cooking, dance around it, etc.
It is a little susceptible to Winter weather so take a few cuttings to be safe.
By the way, this is a 'must have' so if you don't have one already, let me know and I'll take a couple of extra cuttings for you!