Abstract
Two new species, Vincetoxicum izuense and V. hoyoense, are described here. Vincetoxicum izuense is a twining perennial herb on rocky beaches and on the margins of thickets near the sea and is endemic to the southern Izu Peninsula. It resembles V. sublanceolatum and V. japonicum, but V. izuense is distinguished from them by the leaves, follicles and trichomes on the lower surface of the leaves. Vincetoxicum hoyoense is a large, perennial, twining herb on rocks and on the margins of thickets facing the sea and is endemic to the area around the Bungo Channel. Vincetoxicum hoyoense resembles V. japonicum f. puncticulatum and V. sublanceolatum, but V. hoyoense can be distinguished from them by the larger, elliptic or ovate leaf blades with shallowly cordate base and the longer corolla lobes. Although V. hoyoense also resembles V. izuense in flower, morphology and leaf shape, V. hoyoense is easily distinguished from it by the large ovate or elliptic leaves with shallowly cordate base and the large corollas.
