We call it “Rainfarn” in German. It is usually regarded as a weed, perhaps because you often find it on the side of the rail tracks. However, it is beneficial to the garden apparently, but as not sure why. I got myself a few plants from the market from a herb seller. Unfortunately my neighbour decided it looked weedy and mowed it down one year, although it would have survived. However as compensation he bought me 10 plants and now I have a wonderful field of Tansy at the side of my garden: nothing special, but I like its button flowers in Summer.