MONTPELIER, Vt. — For Vermont’s state vegetable, lawmakers are expected to choose one with roots in the state: the Gilfeather turnip. The tasty tuber was developed by John Gilfeather, a farmer and legislator who lived about a century ago, and who crossbred a turnip with a rutabaga. It’s now the centerpiece of an annual Gilfeather Turnip Festival held each October in the southern Vermont town of Wardsboro. With the help of their teachers, schoolchildren from there testified at the Statehouse for their favorite veggie. The turnip got preliminary House approval on Tuesday and is expected to garner final approval on Wednesday before heading to the Senate.