Cynanchum acutum aka Scammony

Cynanchum acutum is a perennial climber in the Apocynaceae family. The RHS calls it the Montpelier scammony plant. Its native range includes Lanzarote in the Canary Islands. It stretches from the Mediterranean to Siberia and northern China. Kew places it within the temperate climate zone. It is not native to Britain or Ireland. Wild plants grow on coasts, river banks, and mountain slopes. They also occur on sandy and salt-affected steppe slopes.

The plant reaches about 10 feet [3 metres] in height. Its stems twine around other plants for support. Kew describes its form as a climbing subshrub or shrub. Plants For A Future treats it as a perennial climber. That source also notes wide variation within the species. These accounts describe a lasting plant with a climbing habit. The leaves and stems contain latex with rubber. The supplied sources give no details of leaf shape or bark.

Flowers appear in July, according to Plants For A Future. Each flower has both male and female organs. Insects carry pollen between the flowers. The evidence gives no flower colour or fruit description. In gardens, the plant can grow in cultivated beds. Its twining stems need other plants to climb over. The sources do not describe a separate ornamental use. They list rubber in its leaves and stems as another use.

Plants For A Future describes this species as easy to grow. It accepts ordinary garden soil and prefers moist ground. It can grow in sand, loam, or clay. Suitable soils range from mildly acid through neutral to mildly alkaline. Full sun and partial shade both suit it. The supplied evidence gives no hardiness zone or winter temperature limit. It also gives no specific pest or disease problems. Plants For A Future does not flag it as weedy.

Seeds can be sown in a greenhouse in spring. Move seedlings into separate pots once large enough to handle. Keep them under glass through at least their first winter. Plant them out in late spring or early summer, after frost risk passes. Spring division offers another way to raise plants. Plants For A Future lists no known food or medicinal uses. Its warning about toxins concerns the genus, not this species alone. That warning does not establish this species’ safety for people or pets.