The situation of Rudbeckia laciniata in the EPPO region
Rudbeckia laciniata (Asteraceae) is a rhizomatous perennial originating from the Eastern USA and which was introduced in Europe as an ornamental plant at the beginning of the 17th century. It spread in Central Europe during the 18th and 19th centuries.
Geographical distribution
EPPO region: Austria, Belgium, Croatia, Czech Republic, Denmark, Estonia, France, Germany, Hungary, Italy, Latvia, Lithuania, the Netherlands, Norway, Poland, Russia, Slovakia, Sweden, Switzerland, United Kingdom.
Asia: China, Japan
Oceania: New Zealand
North America (native): USA (Alabama, Arkansas, Arizona, Colorado, Connecticut, District of Columbia, Delaware, Florida, Georgia, Iowa, Idaho, Illinois, Indiana, Kansas, Kentucky, Louisiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, Mississippi, Montana, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New Mexico, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Vermont, Washington, Wisconsin, West Virginia, Wyoming), Canada (British Columbia, Manitoba, New Brunswick, Nova Scotia, Ontario, Prince Edward Island, Quebec).
Note: in Belgium, the species has not extended its distribution (E. Branquart, pers. comm., 2009).
Morphology
R. laciniata is a large perennial herb, which grows up to 3 m tall, with slightly glaucous leaves, and composite yellow flowers.
Biology and ecology
The species reproduces very efficiently by rhizome fragmentation. It flowers from June to September and produces copious amounts of achenes (1600 seeds per plant), but they can only germinate on disturbed sites.
Habitats
Riverbanks, damp areas, slopes, waste ground, areas with temperate climates, it mainly colonizes places at altitudes lower than 700 m. It prefers humid soils and semi-shade. According to the Corine Land Cover nomenclature, these habitats correspond to: banks of continental water, riverbanks / canalsides (dry river beds), road and rail networks and associated land, other artificial surfaces (wastelands)
Impacts
R. laciniata forms monospecific stands, out competing other plant species, having an adverse impact on biodiversity. It can also alter the habitat dynamic of trees colonization in alluvial areas. It is toxic, and can be lethal to animals (horses, sheep, pigs) if ingested.
It is considered an agricultural and environmental weed in the Global Compendium of Weeds.
Control
Removing rhizomes from the soil can prove efficient but is very time consuming and only possible on small surfaces. Furthermore, this method perturbs the habitat and enhances the germination of seeds present in the soil.
Repeated cutting over several years leads to a statistically significant but small decrease in the abundance and vigour of the plant. Nevertheless, it also allows the germination of individuals from the seed bank.
Planting pioneer forest trees, in particular Alnus spp. and Salix spp., create a shaded environment in which R. laciniata would slowly regress. It is necessary in this case to cut the vegetation that would limit the growth of those trees.
Considering the wide distribution of this species in the EPPO region, the EPPO Secretariat decided not to include R. laciniata in the EPPO Alert List.
Sources
A Global Compendium of Weeds. http://www.hear.org/gcw/alpha_select_gcw.htm
Delivering Invasive Alien Species Inventories for Europe (DAISIE) Database. http://www.europe-aliens.org/
NOBANIS - Network on Invasive Alien Species. http://www.nobanis.org
Muller S (2004) Rudbeckia laciniata In: (2004) Plantes invasives en France. (Ed. Muller S) pp. 114-115. 2004 Muséum national d’Histoire naturelle, Paris (FR), (Patrimoines naturels, 62).
USDA – Plants Profile, Rudbeckia laciniata. http://plants.usda.gov/java/profile?symbol=RULA3
Wittenberg R (ed.) (2005) An inventory of alien species and their threat to biodiversity and economy in Switzerland. CABI Bioscience Switzerland Centre report to the Swiss Agency for Environment, Forests and Landscape. http://www.nobanis.org/files/invasives