Round leaf bittersweet: The invasive vine threatening UK gardens

Round leaf bittersweet is a species of deciduous vine originating from the Far East. Initially, it was cultivated exclusively in Japan, northeastern China, and the Korean Peninsula.

In a short time, it spread worldwide as a popular ornamental plant used for decorating parks, gardens, and facades. In the UK, it is considered a banned invasive species. What should you know about it?

Round leaf bittersweet is a plant from the Bittersweet family. Under favourable conditions, it grows to a height between 10 and 15 metres. The vine is covered with numerous round, slightly elongated leaves. Tiny, white flowers cover the vine in late May and June, eventually turning into small red fruits.

It is straightforward to cultivate and requires little soil. It tolerates drought, heat, and frost generously. It was planted in parks, gardens, and facades just a dozen years ago. Currently, the plant is on the list of prohibited invasive species.

Bittersweet quickly spread beyond the area where it was planted. It propagates through seeds and root shoots, which develop alarmingly. They invade forested regions, preventing the growth of other plants and disrupting the entire ecosystem. When it appears around buildings, transportation infrastructure, or power lines, it can cause severe damage.

Round leaf bittersweet has been listed as a prohibited invasive species. In 2021, the UK government introduced a new law on alien species. The regulation states that cultivating plants listed as alien invasive species is punishable. Violating the current rules can result in a fine of up to £220,000.

In addition to the monetary fine, you risk imprisonment—from 3 months to even 5 years. The length of the sentence or the fine depends on many factors. People who unintentionally contribute to the spread of the plant receive lower penalties.