Lieutenant Tom Bender, the district ranger at the Blue Hills Reservation, will lead people, ages 8 and up, on a two-hour hike into an Atlantic white cedar bog on Sunday. Hikers will explore a world of carnivorous plants and ample vegetation — and do so using a new boardwalk through the bog. For more information and to register for the Ponkapoag Bog Walk, e-mail Tom.Bender@state.ma.us.