This is Aristolochia manshuriensis, also known as Birthwort, and Manchurian pipevine. This exotic looking pipevine blooms from late Spring until early Summer. All Aristolochia species, except for the Aristolochia gigantea, are larval host plants for the Pipevine Swallowtail, Polydamas Swallowtail, and Mylotes Cattleheart butterflies. USDA Hardiness Zones 5 to 10