please tell me how to look after it,and how does it survive it never grows roots but keeps producing flowers, how much water does it need and how deep should it be set,is it hardy, I treat it as a Dahlia but really have no Idea how to keep it. Any help pl

I'm confused about how you're growing it now - what is it growing in? Or have you just got it sitting on a table, not in water, not in a pot?
This plant is a tuber, (like a bulb) is usually grown in light, loamy compost in pots, tolerates quite a lot of dry, needs a bit of sun, doesn't like frost. It's known as a tender, greenhouse or conservatory plant, though it has been found growing outside in very sheltered spots, though any cold will immediately kill the topgrowth, which then returns when conditions are better.