- Lepidium latifolium
Perennial Pepperweed (Lepidium latifolium) is an invader of irrigated pastures, grasslands, rangelands and native meadows, causing the most concern in the Kootenay and Thompson agricultural regions. Plants can grow to 2 m high, with large infestations that can eliminate competing vegetation and damage riverbank habitats.
Perennial pepperweed has a deep, extensively creeping root system, with broken pieces that can travel and lead to more monocultures along roadsides, in fields, and in disturbed habitats. It is common on riverbanks, beaches, marshy floodplains, and seasonally wet areas. It is also a prolific seed producer; one plant can spread over 6 billion seeds per acre, dropping from the plant or travelling short distances by wind and water.
Considered regionally noxious under the BC Weed Control Act, perennial pepperweed is identified by waxy foliage and rounded clusters of white flowers at the end of branches. Leaves are green or greyish-green, with distinctive white veins at their centre. Perennial pepperweed seeds were likely brought to North America mixed with a shipment of sugar beet seeds in the 1930s.