Vincetoxicum hirundinaria aka German Ipecac

Vincetoxicum hirundinaria has two common names: white and pale swallow-wort. It belongs to the dogbane family, Apocynaceae. Its native range spans Europe, western Siberia, and northern Türkiye. It is also native to northwestern Africa. Kew places it in the temperate climate zone. In its native range, it grows on cliffs and slopes. It also grows on rocks that jut from the ground. It is not native to Britain or Ireland. Its older scientific name is Asclepias vincetoxicum.

This plant has soft stems and lives for many years. It spreads through rhizomes, which are stems below the soil. Its shoots start upright, then twine like a vine. Missouri Botanical Garden gives growth per season as 3–6 feet [0.9–1.8 metres]. Its listed full height reaches 20 feet [6.1 metres]. Its listed width reaches 6 feet [1.83 metres]. The smaller range describes shoot growth in one season. The larger sizes describe the full-grown plant. Its leaves can form tangled masses where spread goes unchecked.

Its greenish-white flowers bloom from May to July. The blooms have a scent and draw butterflies. Missouri Botanical Garden calls both the flowers and fruit showy. Both add some value for garden display. Yet its spread gives more cause for concern than its looks. It has escaped gardens in parts of North America. It now grows wild in New York, Michigan, and Ontario.

In gardens, it grows in full sun or part shade. It grows in moist soil and needs a fair amount of water. It can also cope with drought and shallow, rocky soil. Missouri Botanical Garden lists USDA hardiness zones 4–8. That source also calls it easy to grow. It needs little routine care, but curbing its spread takes more work. Deer and rabbits tend to leave it alone. Reports note no serious problems with insects or disease.

Missouri Botanical Garden calls it invasive and says not to plant it. Both rhizomes and plants from self-sown seeds help it spread. Left unchecked, it can cover open ground in woods. It can also cover forest edges, grassland, pastures, slopes, and roadsides. Thick growth shades nearby native plants and can hold back their growth. In some cases, it can crowd those plants out. Easy growth does not make it a sound garden choice. The supplied sources give no evidence of edible uses or toxicity.