Helianthus is a genus of the family Asteraceae. It is a genus exclusive to North America and Mexico with approximately 52 species. economically it is important as a source for sunflowers (Helianthus annuus) or the Jerusalem artichoke (Helianthus tuberosus). Plants can be annuals or perennials.
Helianthus tuberosus is a tuberous species, also known as Jerusalem artichoke. The tubers can be rather large and is grown for food in Europe and some parts of North America. According to the USDA, it is present in most states except Alaska, Hawaii, New Mexico, Arizona, and Utah. Flowers are typical of wild Helianthus with multiple showy golden ray florets and a center of disk florets. In discussions on the PBS list, this species has been given the name 'sunchoke'. An established clump will easily produce several kilograms of extra tubers per year, which store badly but can be harvested throughout winter unless the ground is frozen solid, making this a valuable winter crop.
Pictures below by David Pilling showing the foliage and the tubers. His experience is that you may buy some tubers from the grocery store, plant them and get a reliable seven foot high clump of foliage every year, but (at least in the North West of England) you won't get any flowers. Martin Bohnet reports them to flower in mid October in southern Germany, if not stopped by early frosts. His tubers have a reddish skin, so it may be a different selection.