Hilary,
This one is Justicia adhatoda, a large shrub that doesnt need to be watered once established.
Not recomended for a small sized garden.
It might appear in the book you have mentioned under Adhatoda vasica or Adhatoda zeylanica which is a synonym.
Also known as Malabar Nut, this is quite an important plant in Ayurvedic medicin used mainly to treat respiratory disorders and other problems.