NATIVE RANGE: Western North America

FIRST FINDING IN SLOVENIA: 2017 (a single site, where eradication is underway)

PATHWAYS: horticulture: ornamental plant which is planted on the edge of ponds

POSSIBLE TO FIND: March – August

FLOWERING SEASON: March – June

DESCRIPTION: Herbaceous perennial. In spring, light green leaves emerge from brown rhizomes. Leaves grow to 40–100 cm long and 25–70 cm broad, and have an irregularly wavy lamina. Crushed leaves and flowers have an unpleasant odour. Flowers, which usually emerge before the leaves, are clustered in erect, yellow-green inflorescences, which are 3.5–12  cm long, surrounded by yellow spathes, 10-35 cm long. The flower stem is without leaves, initially short, then elongating. Fruits are green berries, each containing two seeds.

HABITAT: Grows in moist habitats, for example in moist forests, bogs and marshland as well as along streams.

STATUS: Naturalised and invasive, in particularly in some northern European countries.

SIMILAR SPECIES: Asian skunk cabbage (L. camtschatcensis) white spathes and rhizomes. The plant does not have an unpleasant smell. Skunk cabbage (Symplocarpus foetidus) has cordate to ovate leaves. The spathe is purple with green blotches. Native European aroids are much smaller. Bog arum (Calla palustris) has a white spathe, Italian arum (Arum italicum) and Cuckoopint (Arum maculatum) have light green spathes.

IMPACTS: American skunc cabbage can establish populations in moist habitats and form dense stands which outcompete native shore-plants, especially mosses and sedges. 

SOURCE: Field Guide to Invasive Alien Species in European Forests

NOTE: this species is included in the list of Invasive Alien Species of Union concern (the Union list) of Regulation (EU) 1143/2014. The species included on the Union list are subject to restrictions and measures set out in the Regulation. These include restrictions on keeping, importing, selling, breeding and growing. Member States are required to take action on pathways of unintentional introduction, to take measures for the early detection and rapid eradication of these species, and to manage species that are already widely spread in their territory.