I suggest you grow the Italian Arum (Arum Italicum) in a pot buried in the ground if you are concerned about it spreading too rapidly in a small garden. In my own garden with great soil I have not found this shade loving perennial invasive but in certain conditions it may become a nuisance. The foliage is indeed lovely with striking white veins on arrow shaped leaves and the unusual bract covered with red berry like seeds is quite a conversation starter.  Any plant that volunteers or that someone tells to you to "take as much as you want" from their garden can become invasive but might also be just the plant you need for color and texture in a spot like deep shade that not much else wants to grow.  Viva Italy and Keep growing, Marianne Binetti