Other names: Also known as Yellow or Western Skunk Cabbage, Swamp Lantern.
Introduction history in UK
American skunk cabbage originates from the Pacific regions of North America, from Alaska south to California. Small, scattered populations are now present in several countries in northern Europe. It was introduced to Britain in 1901, and was first recorded in the wild in 1947. It is a popular plant in water-gardens, and has been actively promoted by the gardening press. In 1993 Lysichiton americanus received an “Award of Garden Merit” from the Royal Horticultural Society (RHS) Floral Committee. More recently, greater attention has been drawn to its invasive nature. In 2010, the Recording Invasive Species Counts (RISC) project asked the public to submit records of Lysichiton americanus. The RHS website now provides an online leaflet on INNS in which it recommends that gardeners should “Avoid using plants known to be invasive, especially in the case of non-native aquatic species”. Nevertheless, Skunk cabbage is still praised as garden plant. The online BBC Plant Finder describes it as “an asset in any bog garden”, and makes no mention of its ability to spread into the wild. Skunk cabbage is still widely available from plant nurseries.
It is found in a number of locations scattered across Scotland. Most naturalised populations in Scotland appear to originate from botanical collections and private gardens.
A number of control methods have been tried, and found to be generally effective. Given that seed remains viable for many years, it is necessary to monitor sites over a long period.
Success has been achieved by excavating and removing rhizomes, which are them composted on dry ground. On sites with many large plants, this is rather slow and laborious, especially in heavy, waterlogged soils, but can be undertaken by volunteers. Small plants may be most easily tackled by this method.
Spot treatment of plants with a 1:40 glyphosate towards the end of the growing season (late August – September) has been found to be very effective on some sites. Because of the plant’s rosette form, it is possible to use herbicides without damaging non-target plants.
Cutting and treating
Success has also been achieved by cutting plants near ground level in the summer, and applying glyphosate to the cut surfaces. If all ripening flower-spikes are removed as part of this operation, it will prevent further recruitment of seed into the seed-bank.