Vincetoxicum hirundinaria, commonly named white swallow-wort (its seedpods are reminiscent of a swallow's wing, or tail), is a long-lived herbaceous perennial of the genus Vincetoxicum in the family Apocynaceae. It is native to cliffs and slopes, especially in calcareous soils, of continental Eurasia (including some Baltic islands). There are introduced populations in North America (Ontario, Michigan, and New York). The plant was mentioned by Pedanius Dioscorides as a traditional plant used by Dacians and known as "ZOO-USTE", the "herb of animals", believed to open any locked door.