This North American flower - now wild and flourishing in this part of Italy, is called Tompinambur or Rapa Tedesca in Italian. In English it has many names: Jerusalem artichoke, sunroot, sunchoke, earth apple, and topinambour. Having nothing to do with Jerusalem, a page on Wikipedia tells how that name might have come from Italian Americans calling the flower “girasole” (sunflower). It is related, being of the same genus, Helianthus. Somehow along the way the word may have morphed into “Jerusalem”.