American Skunk Cabbage (a.k.a Lysichiton americanus) is becoming quite an issue across the UK countryside. Recently placed on the list of Invasive Alien Species of Union concern, the plant is well known for its distinctive ‘skunky’ odour that emits when in bloom.
Despite its popularity as an ornamental garden plant and available to purchase as recently as 2016, the native species has gradually escaped into the wild causing serious harm to eco systems. The species thrives in habitats such as swamps, wet woodlands and in areas surrounding rivers and lakes.
Skunk cabbage often appears before other native wildlife has started to grow and is easily distinctable with its striking yellow lantern shaped flowers. It can out-compete other native plants dominating large areas and using its leaves and dense stands to cause a shading effect. The species can also cause extensive local damage to native flora and over-time create a problem for biodiversity.
Growing up to 1.5 metres in height, the plants green, leathery leaves secrete a very strong odour which some describe as ‘evil’. The species is highly poisonous and if consumed can cause burning and swelling of the mouth and a choking sensation, its one cabbage you definitely do not want to eat. While it repels humans, this scent attracts pollinators, flies, and beetles, deceiving them into thinking that food is available, and unintentionally carry its pollen to another flower. By imitating the smell of decay, the plant has evolved to exploit the first pollinators of spring.
Often spread along watercourses and by bird or mammals, the plant reproduces almost exclusively by seeds. Per spadix there is between 300-650 seeds and once the large yellow flower disconnects from the stalk, the seeds will germinate next to the mother plant. A large seed bank can build up in the soil and last for up to 8 years.
Drift Reservoir is one of many locations being affected by the spread of this plant. As part of a project with South West Water, we treated an area covering up to 30 square metres. The infestation was small and plants sporadic, allowing us to use a targeted herbicidal treatment over three years which limits the impact of ground flora and is an advantageous method for sensitive areas.
As the plant takes hold, we are likely to see more and more cases, causing problems to increase and if left untreated could become a huge problem across Britain’s landscapes.
